Exam 2 Flashcards
1
Q
polyoma genome structure
A
small, dsDNA (similar to papilloma)
2
Q
what are the human polyomaviruses?
A
JC, BK, and Merkel cell
3
Q
key features of JC and BK polyomaviruses
A
primarily infect the kidneys
persistently infect people but usually do not cause disease
generally are not a problem except in people undergoing transplants
4
Q
key features of Merkel Cell polyomaviruses
A
non common
associated w a rare but deadly skin cancer
5
Q
mononega genome structure
A
neg sense RNA nonsegmented
enveloped
highly conserved genome order
RdRp starts making mRNAs INSIDE the nucleocapsid after entry (3’ to 5’), sequential gene expression, terminating and releasing before reinitiating
6
Q
what type of virus is rabies
A
Rhabdo (mononega)
7
Q
what type of virus is ebola
A
Filo (mononega)
8
Q
what type of virus is mumps
A
paramyxo (mononega)
9
Q
what type of virus is measles
A
paramyxo (mononega)
binds SLAM/CD150
10
Q
what type of virus is RSV
A
paramyxo (also pneumo), (mononega)
11
Q
paramyxo genome structure
A
Neg RNA
No segmented
Enveloped
transcription begins inside nucleocapsid after entry
3’ to 5’
leader as initiation signals
has conserved intergenic sequences between ea ORF
order of genes is conserved
viral RdRp: sequential transcription, terminates and releases ea mRNA before reinitiating at some rate
allows virus to regulate amount of ea protein
12
Q
paramyxo virion structure
A
roughly spherical
loose envelope
nucleocapsid is helical despite virion being spherical
13
Q
paramyxo HN protein
A
hemaglutinnin-neuraminidase (not all, some have just H, no N)
note that F and HN are separate
14
Q
paramyxo F protein
A
fusion protein
has F1 and F2 bound by disulfide bond
starts internal, needs to be cleaved to be functional
note that F and HN are separate
15
Q
paramyxo N protein
A
nucleocapsid
helical
binds EXACTLY 6 nts in genome each
wound as left handed helix
packaged w P and L
16
Q
paramyxo L protein
A
polymerase
packaged w N and P
17
Q
paramyxo P protein
A
phosphoprotein
packaged w N and L
18
Q
paramyxo SH protein
A
small hydrophobic
maybe function as ion channel (like M2 in influenza)
19
Q
paramyxo M protein
A
matrix
20
Q
rhabdo virion structure
A
bullet shape due to wrapping of helical nucleocapsid in supercoil
coiling mediated by M (matrix)
genome complexes to BOTH N and M
21
Q
paramyxo receptors
A
terminal sialic acid residues on glycolipids on cell mem
paramyxo have HN, neuraminidase releases progeny virions that bind to surface of cell
22
Q
what is the measles receptor
A
SLAM/CD150
found on activated BCs, TCs, DCs, and MO
killing imm cells leads to immunosuppression
23
Q
rhabdo entry
A
only have one single glycoprotein (G) that does binding AND fusion (note rhabdo has one protein (G) but paramyxo has 2 (HN and F))
fuse in endosomes not plasma mem
G protein used in pseudotyping other viruses
24
Q
what is pseudotyping
A
producing viruses or viral vectors in combination with foreign viral envelope proteins
using rhabdo G protein allows it to infect many more cells that don’t have its receptor
25
what are the two models of mononegra transcription and which is correct
1. multiple promoter, 2. single entry
single entry is correct - leader seq is only primer, pol (L) transcribes ORF, terminates at intergenic seq, at some freq can reinitiate at the intergenic seq
we know this is correct bc introducing a mutation in one ORF affects all downstream ORFs (multiple promoters would have it only affect that one ORF)
26
paramyxo transcription
3' to 5'
L (pol) binds leader at 3' end, P (phosphoprotein) also binds and helps
L transcribes ORF then falls off, then at some percentage reinitiates, makes N
27
do paramyxo mRNAs have a 5' cap
yes, methylated (typical cap) by L (pol)
28
do paramyxo mRNAs have a poly A tail
yes, obtained from stuttering on UUU repeats (transcribed into As)
29
how does paramyxo regulate its mRNAs and proteins
falling off/reinitiation leads to more 3' proteins than 5' proteins
this is why order is so highly conserved
5' end has L (pol), doesn't need a lot
low N (nucleocapsid) leads to transcription, high N leads to replication
30
how does paramyxo regulate transcription vs replication
Neg RNA is used for both transcription and replication
low N (nucleocapsid) leads to transcription
high N leads to replication
31
paramyxo assembly
After mRNAs are made, glycoproteins made
Glycosylated by ER and golgi, inserted into plasma membrane
Matrix not glycosylated, moves to plasma mem and associate w tails of G
N, P, and L all important for replication as well as secondary transcription (makes more mRNAs and more translation templates)
32
paramyxo P/C/V gene
only paramyxo mRNA that makes multiple proteins
multiple start sites, TRANSLATION machinery can uses any of them
P/V/W are most favorable, P is primarily made (longest form)
P is phosphoprotein, subunit for pol
Can also result in V or W
Caused by stuttering on As (DURING TRANSCRIPTION), that can add an additional 1 or 2 Gs (makes V or W)
Gs loated between poly A tail and GC rich region
Y and C are also important
33
paramyxo differences between transcription and genome replication
Full‐length RNA is encapsidated by N whereas mRNAs are not
when N present, pol starts transcribing, nascent RNA becomes associated w N
N may sequester/hide intergenic seq --> block transcription, drives RNA rep
34
paramyxo assembly and release
envelope glycoproteins insert into ER and glycosylated in glogi
(most) F proteins cleaved by furin (ceullar protease) in trans-golgi right before insertion in plasma mem (prevents fusion during intracellular transport)
M (matrix) associates w cytoplasmic tails of envelope
nucleopcapsids in cytoplasm migrate to plasma mem and interact w matix
bud through plasma mem
Fusion is competent on cell surface (causes cell-cell fusion (syncytia) and tissue destruction)
35
what is different in hendra and nipah F proteins
F NOT cleaved by furin
Moves through ER and golgi and is glycosylated, expressed on plasma mem but REPLICATION INCOMPETENT (F0)
Reendocytosed from plasma mem into endocytic vesicle
Cathepsin L cleaves into competent form (F1 and F2) and then F recycled back to plasma mem
36
what is F0
replication incompetent fusion protein, found in hendra and nipah mononegraviruses before reendocytosis
37
measles transmission
aerosol droplets (remains infectious for a few hours)
transmission days before rash, hard to control
one of the most contagious viruses ever studied
primarily in childhood bc so contagious
lifelong immunity
prevalent where there is no vacc
38
measles spread in body after infection
enters through resp tract
rep in many cells bc of SLAM receptor
First cells infected are lung/aveloar cells and MO and DCs (migratory)
Allows spread when MO and DCs drain to lymph nodes, allows virus infect B and T cells
BCs and TCs circulate through blood, virus can spread to 2’ infection sites (skin and more)
Pantropic bc so many cells susceptible
Entering skin causes rash
Rarely enters brain
39
measles cell tropisms
MO, DCs, TCs, BCs, epithelial, endothelial, neurons
40
measles tissue tropisms
pantropic
lungs, lymph nodes, spleen, liver, kidney, GI tract, thymus, skin, rarely CNS
41
what is viremia
virus in blood
42
measles disease progression
lymph entry, initiates viremia > reaches skin and other 2’ tissues > rep in skin (no symptoms) > signs of infection (prodromal like resp disease) > can make Koplik’s spots > dec virus in bloodstream as Abs are made > rash develops
Rash – starts as viremia dec and Abs inc
Starts at hairline and moves down (toes and fingers last)
5-6 days
Resolves from top down as well
Infectious period before symptoms and thorough onset of rash (long time)
43
Koplik spots
red dots on mucosal surfaces, cheeks, and tongue
associated w measles
44
what causes measles rash
Why rash so late in disease progression?
Not caused by virus rep, caused by immune complex formation
Ab binds virus, forms imm complex, targeted by imm sys
Infectious period before symptoms and thorough onset of rash (long time)
45
what is an imm complex
a molecule formed from the binding of multiple antigens to antibodies. The bound antigen and antibody act as a unitary object, effectively an antigen of its own with a specific epitope (think affinity vs avidity in imm class where one Ab binds multiple Ags or 1 Ag binds multiple Abs)
46
measles outcomes
most resolve symptoms in 1-2 wks
in order of increasing rarity: ear infections (1/10, and possible deafness), pneumonia (1/20), encephalitis (1/1000), death (1 to 2/1000, due to pneumonia, worse where malnutrition is problem), SSPE (1/10,000)
47
what is SSPE
subacute sclerosing panencephalitis
CNS degenerative, YEARS (6-15) after measles infection,
causes ataxia, seizures, death
neurons infected w measles virus develops persistent non productive infections (no imm resp but still pathologic to neurons)
Linked to mutation in viral genome
Bigger problem before vaccination
48
mumps transmission
aerosol transmission
similar parhogenic course to measles (resp tract > local lymph nodes> disseminate via viremia to virually all tissues > widespread inflamm)
most common 2' infection in parotid glands (large salivary glands), CNS, gonads, kidneys, pancreas, heart, and joints
characteristic swelling in neck (spread to parotid glands)
CNS spread can cause meningitis
goand spread can cause sterility (rare)
vaccinated for w measles (MMR)
49
what is in the MMR vaccine
protects against measles, mumps, and rubella (pos sense togavirus)
99% reduction in measles (start in 1963)
US declared eliminated in 2000
2019 saw highest rates of measles in long time
MMRV becoming more common (V = varicella (chickenpox))
50
Andrew Wakefield (aka the asshole)
"linked" MMR vacc to autism and IBD, tried to push his own vacc series w components
no reproducible data bc he's an ass
51
mumps outbreaks
2006 - midwest college students in dorms (mostly vaccinated)
spread made worse by slow diagnosis - Drs hadn't seen mumps in long time
2015-16 in college campuses
2016-17 in NW Arkansas
2018 had lowest total of recent outbreaks, but in many places
52
RSV transmission
most common cause of pneumonia and fatal acture resp tract infections among infants
v common (2/3 of infacts infected by 1yr old)
v infectious
transmitted through aerosol droplets or fomites (stay long time)
no vacc
53
RSV pathogenesis
respiratory but v diff from measles and mumps
Spreads from one cell to another along endothelial cells of resp tract
Limited to lungs, no lymph node spread
Can cause severe pathology in the lungs tho (bronchitis and pneumonia)
can cause apnea and chronic lung disease later in life
Formulin inactivated vaccine made in 1960s but made it worse (withdrawn)
Repeated exposure over time, immunity wanes but repeat infections inc immunity again, only infants are symptomatically infected
54
Rabies (rhabdo) transmission
animal bites (usually bats in US, can also be foxes, or racoons)
domestic cats have it more than domestic dogs
1 case a yr in North America
causes encephalitis
once there is symptoms, nearly always fatal
long latent period between bite and symptoms allow for post exposure vaccination
55
how are wild animals vaccinated for rabies
editable baits dropped from planes that have an oral vaccine in them
56
rabies spread in body after infection
animal bite > virus rep in muscle at site of bite > virus infects nerve in PNS > virus spread via retrograde transport > virus rep in dorsal root ganglion > travel from spinal cord to brain > brain infected > virus travels from brain to other tissues (eyes, kidneys, salivary glands)
57
rabies symptoms
Headache, fever, general weakness
Cerebral dysfunction, anxiety, confusion, agitation
Delirium, abnormal behavior, hallucinations, insomnia
Mania and eventually coma
Primary cause of death – respiratory failure (brain stops telling you to breathe)
58
Milwaukee protocol
put patient in induced coma to 'protect them from their brain', buys imm sys time to clear infection
treat w antivirals and chemically induced coma
respirator keeps patient breathing
worked 3 times total with no rabies vacc, 5/30 times including rabies vacc
very long rehab
59
Ebola first outbreaks
1976 started in north Zaire (now Democratic Republic of Congo) then south Sudan
near Ebola river
outbreaks were back to back but they were 2 diff outbreaks w 2 diff strains
the first outbreaks were limited and sporadic bc of the isolated communities they happened in (until 2014)
Zaire - 88% fatality
Sudan - 53% fatality
60
Ebola 2014 outbreak
West Africa
initially looked same, within months it multiplied at a staggering rate
why? located in a much more dense city
61
Ebola 2018/19 outbreak
the next most impactful outbreak after 2014
Happening more in dense populations
(may be getting worse)
62
Ebola reservoirs
thought to be classic zoonotic
apes and humans susceptible but END HOSTS bc too deadly, not good spread (not reservoir)
reservoir believed to be fruit bats (not proven tho)
evidence: some bats have pos serology (Abs) for Ebola, migration patterns similar to outbreak locations, exposure correlated to outbreaks
bat exposure and consumption is common in these areas
63
ebola transmission
classical zoonotic
fruit bats to humans (maybe)
human to human (family, caretakers, medical staff, and funeral staff)
infects MO and DCs
64
Ebola genome structure
neg sense RNA
mononega order, filo family
enocodes 7 proteins, including 3 forms of glycoprotein: GP, sGP, and ssGP
65
Ebolavirus vs Ebola virus
Ebolavirus = family (one word)
Ebola virus = species (two words)
Family (one word) contains both initial strains (Zaire and Sudan)
Zaire stain – Ebola virus
Sudan strain – Sudan virus
Focusing on Ebola virus (Zaire)
66
Ebola virion structure
filamentous
enveloped
helical capsid
"knot" or loop at end
diameter about 80nm (normal), length up to 14,000nm (insanely large for a virus)
67
ebola GP protein
glycoprotein
GP is transmem, embedded in envelope, facilitates virus entry
68
ebola NP protein
nucleoprotein, encapsidates the neg RNA genome and protects it
Genome + nucleoprotein = nucleocapsid
Filamentous helical structure – irregular proteins individually, but tightly buttress to ea other to form helical shape
Genome is completely protected by the nuceloprotein
69
ebola VP30, VP35, and L
replications proteins that associate with nucleoproteins
L is RdRp
70
ebola L protein
pol (RdRp) associated w capsid
71
ebola VP40 protein
matrix that forms filamentous structure and connects to envelope
72
ebola sGP and ssGP
secreted glycoprotein
slows host Ab response to virus by binding Abs in place of binding to actual virus
73
how does ebola get its envelope
'stolen' from host cell, contains viral glycoproteins (GP important for entry)
74
ebola entry
binds target (DCs or MOs)
entry via macropinocytosis (enters in endosome)
Normally endosomes degrade conents bc low pH, Ebola uses it
Acid activates host proteases, cleave GP, opens receptor binding domain (RBD), binds receptor inside of endosome
NPC1 is receptor
Membrane of virus fuses w mem of endosome, nucleocapsid release to cytoplasm
75
what is NPC1
receptor inside of endosome that ebola uses to fuse to vesicle mem and release into host cell cytoplasm
76
ebola genome replication
Need to make pos from the neg genome
Pos works as mRNA for translation and templates to make more neg (for progeny)
As more nucleoprotein is made it encapsidates genome, join w rep proteins, bud out of cell through mem
‘steals’ lipid envelope and viral GPs that have inserted themselves on the plasma mem
Bud vertically (most of them) or horizontally (occasionally in some types of cells)
Makes solube GPs, slows host Ab resp to virus
v fast rep, large titer in 4-5 days (before imm resp can stop it)
77
ebola pathogenesis
onset 7-9 days
can be asymptomatic in beginning
early symptoms nonspecific while virus is at high titers (fever, aches, etc)
nonspecific symptoms lead it to be confused w malaria, yellow fever, and dengue (missing it allows for more spread)
progress to multi-organ involvement (bleeding everywhere, coughing, vomiting, etc) leads to dehydration and hypovolemic shock which can cause death
not all patients get all symptoms
progress to late peak (blood in tissues, oozing from punctures, disseminated intravascular coagulation)
now it is Ebola Hemorrhagic fever (EHF)
78
ebola early symptoms
Fever, Headache, Chills, Malaise, Myalgia (joint/muscle pain), Nausea, stomach pain, Macropapular rash (flat red lesions) in some cases
79
ebola multi-organ symptoms
Systemic (prostration)
Gastrointestinal (vomiting and diarrhea with blood)
Respiratory (coughing w blood, chest pain, cough, shortness of breath)
Vascular (conjunctival injection, bloody nose, edema, hypotension)
Neurological (headache, confusion, coma)
Dehydration and hypovolemic shock
Without hospital intervention (fluids), die
80
what are the key symptoms of ebola infection
bloody nose and blood in whites of eyes (conjunctival injection)
not all patients develop all symptoms
81
ebola late / peak symptoms
Petechiae (small red spots)
Ecchymoses (blood into tissues)
Hemorrhaging from mucosal sites
Visceral hemorrhagic effusion (hemorrhaging into lining of lungs)
Uncontrolled oozing from venepuncture sites
result from “disseminated intravascular coagulation” (DIC)
called “Ebola Hemorrhagic Fever” (EHF)
82
what is DIC
disseminated intravascular coagulation
abnormal clotting in blood vessels that uses up all clotting factors, leading to massive bleeding in other complications
83
what causes DIC
Cannot clot, loss of blood even after transfusions
DIC - massive activation of coagulation factors in blood, clots all over body, used up and cannot respond to actual injuries
Leads to abnormal bleeding in other locations
result of abnormal reaction to infection
Aberrant bleeding also disrupts normal blood flow to organs (like kidney) which causes multi organ failure from lack of oxygen
84
ebola final stage symptoms
shock
convulsions
multi organ failure
death
Fatality rate can be higher than 80%
85
ebola spread in body after infection
Contact to skin (or mucosal sites) > infect resident MO and DCs > drain to regional lymph nodes > induce inflamm resp > cytokine release (causes inflamm resp and depletion of lymphocytes by recruiting more to infect) > rep to high titers > enter blood > disseminate to all peripheral 1’ organ systems > rep in peripheral organs (liver) > dec coagulation factor production > rep in lung, kidney, heart, brain > multi organ failure
Virus cannot infect TCs but induces TC death
Liver is especially important bc virus in liver severely reduces amount of coagulation factors made
coagulation factors are used up (imm resp) and more cannot be made (liver)
86
ebola immunopathology
infection of DCs and MOs induce cytokiens (massive inflamm resp), recruits more DCs and MOs, pos feedback loop
infection of DCs block costim molcules that TCs need, TCs cannot activate, die, lymphocyte apoptosis
massive inflamm resp uses up coagulation factors and causes vascular leakage
87
what part of the imm sys does ebola VP24 block
IFN type 1 (innate)
88
what part of the imm sys does ebola VP35 block
IFN type 1 (innate) and DC maturation (adaptive bc cannot stim TCs)
89
what part of the imm sys does ebola sGP block
anti-GP neutralizing Abs (humoral)
90
the role of coaggulation factors in EBOV
inflamm resp uses up coaggulation factors
ebola in liver prevents synthesis of new coaggulation factors
widespread and uncontrollable internal and external bleeding
91
ebola treatment
short window between severe disease and death
hospital support (fluids, electrolytes, other organ complications, etc) extends window, buys time for imm sys
two approved treatments: Inmazeb (REGN-EB3; combination of three monoclonal antibodies)
and Ebanga (MAb 114; single monoclonal antibody)
Both therapeutics use antibodies that bind to Ebola glycoprotein, preventing infection of cells
92
ebola vaccines
approved in 2019 (rVSV-ZEBOV (Ervebo) )
single dose
safe and protectve for Zaire
use in outbreaks in ring vaccination method - vacc population surrounding outbreak, contain outbreak
93
reo genome structure
dsRNA (only dsRNA we are focusing on)
segmented
dsRNA is fully complementary (right hand helix)
nonenveloped but have protein layers (have some enveloped properties)
mRNAs synthesized and capped inside cores and extruded through channels to cytosol
dsRNA made and maintained in core-like subvirion particles --> protected from antiviral resp
RdRp packaged in virion
94
reo genome segments characteristics
10-12 segments
dsRNA, fully complementary, right‐handed dbl helix
mostly monocistronic (some have alt translation start sites)
Virion has 1 copy of ea segment (must have mech for packaging)
Arranged in parallel and equivalent distance
can reassort during co‐infection --> adaptation
Segments may be linked??Conserved 5' and 3' ends
5' caps but no poly A tails
subterminal regions conserved among homologous genes of diff strains
UTRs v short --> may have role in packaging and transcript/rep initiation
95
reo genome segments subterminal regions
at both 5' and 3' ends
include UTRs and beginning (or end) of ORFs
highly conserved among homologous genes of diff virus strains --> selective pressure to maintain independent of protein-coding functions
96
what type of virus is rota
reo
97
what is the main difference in the rotavirus virion compared to most other reovirus virions
it has 3 proteion chells instead of 2
98
orthoreovirus disease
aka reovrisues
cause uppper resp and GI infection, gennerally asymptomatic
99
where does the name reo come from
respiratory enteric orphan
porhan bc no onvious symptoms at first
now known that rota is major cause of diarrhea
100
rotavirus disease
major cause of childhood gastroenteritis
101
orbivirus disease
Transmitted by arthropods (arboviruses); little human disease; important pathogen of domesticated ruminants (bluetongue disease)
102
coltvirus disease
Arboviruses; Colorado tick fever can cause fatal encephalitis/hemorrhagic fever in humans
103
rota virion structure
non enveloped 2 or 3 (rota) layered structure
8 viral proteins, no cellular proteins
inner capsid/core: genome + rep complexes, surrounds tightly packed dsRNA segments
outer capsid: 12 spikes project from core through to outer capsid at 5-fold axis of symm (RNA pol complexes at base of ea spike)
only rota has intermediate capsid
104
turreted vs non-turreted virions
reo
infectious virions have spikes, during rep process spike is lost --> transcriptionally active subviral particle
Turreted – during rep has large protruding proteins
Nonturreted – Smooth (rota)
105
viroplasm
reo
location of genome replication, able to sequester dsRNA away from host antiviral resp
not at mem like many other viruses
made up of VP2 and 5
106
subviral particle
reo
transcription competent
107
reovirus replication
Binds host receptors, receptor mediated endocytosis, in endocytic vesicle, outer layer degraded, makes infectious particle into subviral transcription competent, can also escape vesicle and release core into cytoplasm, transcription in core (sequester away dsRNA), transcription makes mRNAs, mRNAs are extruded out, translated using host machinery (has 5’ cap), proteins assemble into viroplasms (genome rep, sequesters dsRNA), assembly, budding into ER lumen (remember non enveloped)
108
reo attachment and entry
spike = sigma 1
tail of spike can bind sialic acid > scanning of virion along epithelial cell surface, scans until it finds JAM-A (at tight juncts) > JAM-A binds at head of spike >
receptor mediated endocytosis via beta integrins
Once in endosome, loss of outer layer --> ISVP
Transcriptionally active, cannot transcribe in endosome, escapes into nucleus, looses more intermediate capsid proteins, release of core
spike acts as channel where mRNA can be extruded out
109
what is ISVP
infectious subvirion particle (reovirus)
transcriptionally active
transcription occurs inside the particle
spike protein acts as channel for mRNA to exit
spike looks bigger on ISVP bc loss of outer layer
110
rota particle conformational changes during primary replication
virion enters w 3 layers, one RdRp complex at base of ea spike protein bound to one genome segment
looses outer layer to become transcriptionally active ISVP, loosing outer layer causes upward and outward movement of VP6 (intermediate) and 2 (inner), causes expansion of channel at spike protein, nt can enter, transcription occurs
can have 12 transcription events at same time (one for ea spike and genome segment)
mRNAs are extruded for translation, capped by their way out
111
rota VP7
outer capsid layer
112
rota VP 6
intermediate capsid layer
113
rota VP2
inner capsid layer
114
rota VP4
spike protein
acts as channel to extrude mRNA
caps mRNA (methyltransferase activity)
(λ2)
115
rota VP1
RdRp
active after loss of outer capsid layer
found inside inner capsid
(λ3)
116
rota VP3
supports pol
found inside inner capsid
(μ2)
117
do rota mRNAs have 5' cap
yes, acquired while exiting ISVP through spike channel
spike has methyltransferase activity
118
what is the moving template model
rolling circle of replication, pol continues to transcribe RNA while finished mRNA is extruded from ISVP and new NTPs come in
happens bc the RNA is ds, uses neg RNA to make pos mRNA
119
rota λ2
spike protein
can cap mRNA
(VP4)
120
rota λ3
pol, RdRp
(VP1)
121
rota μ2
RdRp cofactor (VP3)
122
how does reo regulate translation
similar to host:
Length of mRNA (shorter = more)
Seq context around AUG initiator codons (how strong attraction to pol)
Diff in length and 2' structure of 5’ NTRs
in host, poly A tail also regulates, reo does not have tail, may have seq that have similar functs
123
what are intracytoplasmic inclusions
sites of 2' transcription and replication
contains viroplasm (VP2 (inner capsid) and 5), dsRNA, virions at diff stages of maturation, and crystalline arrays of mature virions
associated w cytoskeleton
do NOT contain mem like other viruses
form rapidly (4 hpi)
124
where does 2' transcription and replication occur in reo
intracytoplasmic inclusions
in viroplasms
125
what is DLP
double layered particle
126
what are early replication complexes
one copy of ea 10-12 reo mRNAs assembled into subviral particles
located in inclusions
127
what are replicase particles
dsRNA genomes in subviral particle (result of pos mRNA being copied by RdRp to form the 10 dsRNA genome segments)
2 downstream options: 2' transcription (majority) or virion assembly (minority)
located in inclusions
128
what happens in 2' transcription
dsRNA genome in subviral particle made (back) into mRNA
the bulk of mRNA is a result of 2' transcription not incoming genome
129
two functions of reo RdRp (pol)
In cores, makes ss‐mRNAs using dsRNA template that remains intact and can be used multiple times (circling transcription)
In replicase particles, makes dsRNA genomes using ss‐mRNA template
130
why do reovirus use 2 step (1' and 2') transcription
ensures one segment in every virion
segregates dsRNA within subviral particle away from host
131
reovirus assembly
NSP4 may interact w VP4 (spike) to recruit dbl layered particle (DLP) and VP7 (outer) in ER mem
Induces ER mem to wrap around particle and bud into lumen
NSP4 and ER mem are removed, allowing VP7 to assemble onto the DLP (3 layers total in rota)
NSP4 is in virion but needs to be removed (non structural protein)
NSP4 lost w ER mem (not well understood)
Also allows VP7 to associate w dbl layer
Nonenveloped virus but has envelope at this stage bc of ER mem
132
rota epidemiology
gastroenteritis most severe in v young (6mo to 2yrs) and developing countries
ubiquitous (90% have Ab by 3yrs old)
clearance does not give full protection but repeated exposure results in adults being resistant to infection
has seasonality (peak in winter, possibly more stable at cool temp but not certain)
passed on fomites or direct exposure
133
rota symptoms
1-2 days post exposure, 2-3 days fever and vomit, then 1-5 days diarrhea
can cause severe dehydration (dehydration can be lethal)
134
villus enterocytes
ADSORPTION
near tip of villi
mature nonproliferating cells covering villi that are digestive/absorptive (absorption); express digestive enzymes on apical surface
135
crypt cells
SECRETION
near base of villi
progenitors of villus enterocytes; lack well‐defined microvilli and absorptive functions; actively secrete Cl‐ ions into intestinal lumen (secretion)
136
villi vs microvilli
Large projections on gut wall = villi
Small projections on surface of cells = microvilli
microvilli have actin as anchor
137
brush border enzymes
expressed along MICROvilli
digestion of sugars, nucleotides, and proteins
act as transporters
138
rota pathogenesis
small intestine
infects mature enterocytes in mid and upper villous epithelium
leads to cell death and villus atrophy (shortens bc of cell death)
v few mature villus cells are infected (and no crypt cells)
mild inflamm
results: reduction in absorptiion, toxigenic effects of enterotoxin (NSP4), stimulation of enteric nervous sys, disorganization of brush border actin cytoskeleton causes impaired apical targeting of digestive enzymes
139
rota pathogenesis: direct effects of cell damage
kills mature enterocytes at tips of vili
reduction in absorptive surface
crypt cells try to replace dead cells
diarrhea can precede blunting of villi
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rota NSP4 pathogenesis
coordinates assembly by interacting w DLP and VP7
enterotoxin - can use small fragment, inc intracellular Ca w/o rest of virus
able to mediate diarrhea w/o major cell damage
can be secreted by infected cells to affect neighbors
enterotoxin alone can cause necrosis (w/o virus)
doesn't need high infectivity bc enterotoxin is mediating disease
binds integrin to inc intracellular Ca
breaks tight juncts --> water leaks
ENS can also change Ca lvels in crypt cells
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enterotoxin
toxin that stimulates net secretion in intestinal segments in the absence of histological alterations
usually bacterial, viral are rare
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enteric nervous sys (ENS) in rota infection
Stimulation of ENS causes intestinal secretion of fluid
block ENS --> attenuate rotavirus‐induced diarrhea
causes secretion in crypt cells (they are uninfected)
might be triggered by NSP4, chemokines, and prostaglandins
143
brush border in rota infection
Disruption of actin filaments via VP4 (spike)
needs to disrupt actin cytoskeleton to release virus
144
rota dissemination
viremia and 2' spread but no associated disease diff from normal infection
transient detection of rotavirus Ag and viral RNA in blood of infected children in fatal cases
Virus can repl in DCs, MOs, and BCs – possible mech of dissemination
145
rota transmission
fecal-oral
v high shedding in stool
require v low number to transmit
v easy to spread
146
rota vaccines
1998 - 1st vaccine, tetravalent, mix of monkey and human segments
associated w intestinal intussusception --> withdrawn
2006 - 2 vaccines, high efficacy
RotaTeq - human-bovine reassortant (pentavalent)
Rotarix - human live attenuated
may still cause inc intussusception but not withdrawn (benefit outweigh risk)
vaccines seem less effective in developing countries
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retro genome structure
pos RNA, RT to dsDNA
small genome
TWO GENOME COPIES PACKAGED
Repeat (R) at both ends
U5 and U3 at respective ends adjacent to R
3 ORFs: Gag, Pol, and Env
complexed w NC (nucleocapsid)
has 5' cap and poly A tail
5' and 3' splice sites
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retro virion structure
spherical
enveloped
capsid can be icosahedral or conical (HIV1)
bud at plasma mem
RT, PR, and IN packaged in virion
gp120 and gp41 are envelope glycoproteins
kissing loop - two copies of genome in head-to-head conformation
PBS bound to cellular tRNA (5' end)
149
retro kissing loop
seq in U5 that mediates association of two copies of genome in head‐to‐ head configuration
makes dimer of genomes
150
what is a provirus
DNA copy of retrovirus genome
can be integrated into host chromosome
can cause cancer depending on where it integrates and the genes it disrupts
151
retro oncoviruses
alpha
beta
gamma
delta
epsilon
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retro lentiviruses
slowly progressing, wasting disease
HIV1
153
HIV Gag
group specific Ag
includes structural, MA (matrix), NC (nucleocapsid), and CA (capsid)
154
HIV Pol
enzymes
includes protease (PR), RT, and integrase (IN)
155
HIV Env
envelope glycoproteins
includes gp120, gp41, and Vpr
156
retro genome 5' to 3'
cap, R, U5, PBS, Gag, Pol, Env, ppt, U3, R
157
retro SS
splice sites, important for packaging
158
retro ppt
polypurine tract, important for RT
159
HIV nonstructural proteins
Vif
Vpu
Tat
Rev
Nef
160
retro life cycle: early phase key steps
binding, fusion, release NC, RT converts ssRNA to dsDNA, integrates into host genome
161
retro spike protein structure
spike has 3 gp120 (surface of spike) and 3 gp41 (stalk of spike)
162
retro attachment and entry
gp120 (surface of spike) binds CD4 (TCs and MOs)
conformational change in gp120, exposes 2nd binding site for coreceptor
coreceptor binds (CCR5 or CXCR4, they are chemokine receptors)
another conformational change, this time in gp41 (stalk of spike)
mediates fusion w plasma mem
nucleocapsid is released into cytosol
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retro RT protein
dimer
two activities: Polymerase (RdDp or DdDp) and RNase H(hydrolyses RNA part of RNA/DNA hybrid)
makes DNA INSIDE virion core
error prone --> results in quasispecies and adaptibility
164
retro tRNA
cellular
acts as primer for DNA syn
binds PBS on viral RNA
165
steps of reverse transcription: overview
1. syn of minus-strand strong stop DNA
2. RNAse H digestion
3. first strand transfer
4. syn of full length genome
5. RNAse H digestion
6. Syn of plus-strand strong stop DNA
7. RNAse H digestion
8. second strand transfer
9. extension of both DNA strands
result: proviral DNA
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retro preintegration complex
proviral DNA (dsDNA) associated with components of the virus core
167
retro nuclear import
done w preintegration complex
most retroviruses can only integrate in dividing cells (breakdown of nucleus)
Lenti (like HIV1) has specialized proteins: MA, Vpr, and IN
168
HIV MA
matrix
encodes classical nuclear import signal that interacts w importin
169
HIV Vpr
mediates preintegration complex passage through nuclear pore
170
HIV IN
catalyzes viral DNA integration
brings 2 ends of linear DNA together and in close proximity to cellular DNA
seems to integrate at random sites
LTRs are integrated as well
mediates preintegration complex passage through nuclear pore
171
Trim5alpha
promotes degradation of capsid --> no RT
monkeys but NOT HUMAN work on HIV1
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2 retrovirus integration outcomes
latent infection: Does not contributed to disease but the largest hurdle to treatment and cure
Mem TCs and MOs are the ones w the proviral DNA, act as reservoir
HAART targets RT and IN, but if integration already happened, it has no effect
Latently infected cells are also not recog by imm sys
If taken off of HAART, cells will undergo lytic infection
active infection: virus proceeds with late phase of replication and progeny virus is made
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what is 'shock and kill' treatment
Shock and kill activate all cells to undergo lytic replication and treat w massive amounts of antivirals
174
retro translation
TATA box upstream of U3/R junct --> mRNA w/o U3 bc of where TATA box is, R at 5' end now
U3 has enhancers
PolyA signal at R/U5 junct --> mRNA w/o U5 bc of PolyA tail
mRNA is IDENTITCAL TO INCOMING GENOMIC RNA OF VIRUS
Provirus has U3RU5 at both ends, while incoming genome only had R U5 and U3 R at either end
Gets capped and polyadenylated
Makes Gag and gag-pol poly proteins
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LTR conundrum: left
why only left LTR initiate transcription?
RNA pol at left hand LTR can dislodge pol on right side --> promoter occulsion
evidence: if left deleted, right can initiate cellular translation
176
LTR conundrum: right
why only right LTR singla cleavage and polyA?
Some do it in U3 bc it is only in incoming RNA molecule, it is not in the RNA from the transcription, can’t happen on left hand side
Option 2 is to have it in R region but they have U3 seq that enhance recognition of the poly A signal or U5 seq that repress recog of poly A signal
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2 mRNAs made by retroviruses
Gag-pol
Env --> result of 5' and 3' ss that remove Gag and Pol, bringing two ends together
note that complex retroviruses have many diff splicing and donor sites to make many more mRNA
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retro exit
NC in Gag polyprotein binds viral genome and Gag forms multimers
Exposes myristate in MA, causes targeting of plasma mem
Env interacts w MA, P6 at opposite end interacts w host ESCRT machinery
ESCRT‐III scission between cell and immature virion mem --> release of virus
note: buds as IMMATURE virion, protease inactive until after polyprotein oligomerizes and budding (makes PR good antiviral target)
179
HIV Tat and Rev
transactivator of transcription
regulatory
control vrial rep
upreg viral protein
ESSENTIAL
binds buldge (stem-loop), brings host proteins (Cdk9) which phos RNA pol --> inc processivity
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HIV Rev
regulator of expression of virion proteins
regulatory
control vrial rep
upreg viral protein
ESSENTIAL
shuttle viral mRNA into cytoplasm for translation
for the 9kb (unspliced) and 4‐kb (singly spliced) mRNAs
Both have cis-acting repressive seq (CRS)
Rev binds RRE in mRNA, interacts w host export proteins, overrides CRS, shuttles them out of nucleus to cytoplasm
Rev has NLS so it can be recycled
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HIV Vif
viral infectivity factor
Accessory (non essential in vitro, highly conserved in vivo)
binds APOBEC3G and degrades it, prevents it from bing packaged in progeny vrions --> virus can infect next cell
APOBEC3G (makes C into U), results in misincorporation of nt, inc mutations in viral genome (no proofreading)
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HIV Vpr
Virion protein R
Accessory (non essential in vitro, highly conserved in vivo)
active transprot of preintegraion complex into nucleus
arrests cells in G2 stage of cell cycle --> inc LTR transcription
183
HIV Vpu
virion protein unique to HIV1
Accessory (non essential in vitro, highly conserved in vivo)
1. Degrades CD4
Why degrade own receptor?
Already infected, doesn’t need more
CD4 can interact w gp120 in ER lumen, retention of gp120 in cell, not as much at cell surface, needed for budding
Degrading CD4 allows for more gp at plasma mem
2. degrade tethrin
inc virus release from plasma mem by
Normally tetherin binds progeny virion, keeping them stuck to infected cell, taken back up and degraded
Same vibe as influenza getting stuck w/o neuraminidase
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HIV Nef
Accessory (non essential in vitro, highly conserved in vivo)
1. blocks expression of CD4 and MHC1
block CD4 by inc cycling
block MHC1 by blocking trafficking out of glogi
2. enhance infectivity (we don't know how)
3. modify cell signaling
activating TC, promoting virus rep w/o proper imm resp
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Origins of HIV
Comes from monkeys
Probably derived from SIV, usually causes asymptomatic infections
Chimp infected w 2 diff SIV, rearrangement, then spread to humans
Know that it did come from primates and from 2 diff SIV that recombined and then infected humans
186
HIV prevalence around the world
US --> 1%
subsaharan africa --> 1-5 to over 10% of population (worse more south)
why? Culture – safe sex
Access – HAART therapy
187
HAART
Highly active antiretroviral therapy
not cure, just suppression
most antivirals target RT or PR
needs to stay on lifelong and take meds every day
need cocktail bc of 1. fast rep, 2. RT high mut rate, 3. ability to recombine
HAART inc CD4 TC numbers --> imm reconstitution
HAART has resulted in striking dec in HIV mortality (side effect is that more people have HIV bc they are not dying)
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HIV transmission
blood, semen, vaginal secretions, breast milk
exposure to mucous membranes
unprotected sex and needles in developed
almost eliminated: mother to fetus and blood products (transfusions)
DOES NOT DIRECTLY INFECT CELLS IN VAGINA OR GUT, NEED TO CROSS MUCOSAL BARRIER
facilitated by abrasion, inflamm, or ulcerations
can also be facilited by DCs
189
HIV cell tropism
DCs and MOs - nonspecific (importnat for initial infection bc of sampling and spread)
TCs - specific imm cells (specifically ThCs)
190
HIV spread within body
infects DCs (mostly), MOs, and CD4 TCs in lamina propria > DCs activated, go to lymph nodes > virus rep and spread to other cells in lymph nodes > exit via lymphatics > dissemination to 2' organs > 2' amplification and peak shedding
191
HIV peak shedding
causes imm activation CD8 TCs (diff than infected) and Abs control infection
HIV goes latent in CD4 TCs
Crazy amount of shedding during peak but then goes into clinical latency
192
HIV diagnosis
Abs (3wks post inf), Ags (2 wks post inf), or viral mRNA (1 wk post inf)
Serology (Abs) most common - 20 min spit tests (lateral flow assay)
193
lateral flow assay for HIV
20 min spit test
same set up as pregnancy/COVID tests
false neg - test too early after inf, no Abs yet
false pos - maternal Abs in babies up to 18 mo
can dbl check w PCR for viral mRNA or ELISA for Ag
194
HIV progression to AIDS
3 phases:
1. Acute
2. clinical latency
3. AIDS
195
Acute HIV phase
Median load is 10^6‐10^7 RNA copies/ml at peak, drops to 30,000 within 6‐12 mo
imm will shut down viral rep but level is maintained
if medicated can stay here
rapid (2-3 yrs), intermediate (vast majority, 8-10yrs), and slow (rare, non/slow) progression of AIDS determined by viral load at latency set point
196
clinical latency HIV phase
variation in timing, 2yrs to decades
asumptomatic but virus is NOT DORMANT
gradual depletion of CD4 TCs and destruction of lymph nodes
'asymptomatic progression'
TC depletion both from lysis and chronic imm activation
TC depletion > cannot control virus levels, release into circulation (progression to AIDS)
197
asymptomatic progression
HIV clinical latency
disease is worsening, but no obvious symptoms
gradual depletion of CD4 TCs and destruction of lymph nodes
VIRUS IS NOT DORMANT IN CLINICAL LATENCY
198
HIV exit of clinical latency
TC depletion > cannot control virus levels, release into circulation, leads to AIDS
start to have symptoms: fever, sweat, fatigue, diarrhea, weight loss, infections, neoplasia, neuro (dementia, NM disorders)
199
HIV AIDS phase
AIDS is syndrome, HIV is virus
NEED DEFINING FEATURES:
CD4 count < 200 cells/ul (normal is 500-1000)
Appearance of either:
AIDS‐definining opportunistic infection
AIDS‐defining cancer
200
AIDS cancers
opportunistic cancers
significant cause of death, even w HAART
KS, non-Hodgkins lymphoma, invasive cervical
201
HIV monitoring
both CD4 TC levels (flow cytometry) and HIV1 RNA levels (RT-qPCR)
202
HPV genome structure
dsDNA genome
circular genome
naked capsid
small genome, complexed w cellular histones in nucleosome structure
8 early (transcription and regulation) and 2 late (capsid) genes
LCR (long control region) contains Ori and cis-acting signals
2 promoters: E and L
L promoter can make some E genes
203
HPV virion structure
icosahedral
nonenveloped
virion made of L1 and L2 proteins
72 capsomeres – each with 5 L1 proteins and 1 L2 protein
small relative to other DNA viruses
204
HPV tropism
highly species specific highly tissue specific
virus that causes foot warts doesn't cause warts in other areas
makes hard to study bc can't use human to infect mouse
100% of cervical cancers linked to HPV
205
koiliocytes
cells infected w HPV, have large gaps --> virus is rep in that area
identified on pap smears
proceed tumors
206
HPV strain classification
High risk - 15 strains
*HPV 16 and HPV 18*
cause the majority of cancers
low risk - most others
HPV 6 and 11 cause the majority of genital warts
207
HPV prevalence
most common STI in US
more than half of sexually active people have or have had HPV
43% of women have genital HPV, 7% of adults have oral
burden highest in developing countries - not just bc of cancer care, also bc lack of pap smears so no early detection
208
HPV transmission
skin - direct contact w infected person or surface
genital - sexual contact, mucosal epithelial serve as reservoir
tissue specificity - skin OR genital
209
HPV lifecycle through infected epithelium
infect epithelium live cells as basal layer
infected cells move up towards apical side as cells differentiate new skin is made
HPV requires hijacking host rep cycle, needs to be in live cells --> requires break in apical layer so virus can enter
basal cells show plasmid replication and early gene expression
keratinocytes have vegetative replication, late gene expression, assembly of particles
apical cells die and virus is released
210
hyperkeratosis
piling of cells (keratinocytes) on ea other
warts
211
HPV E7
activates cell cycle progression
Rb is tumor suppressor, cell at rest has RB bound to E2F --> no cell cycle
when Rb phosphorylated, release E2F --> cell cycle progression
HPV E7 binds Rb, Rb cannot inhibit E2F --> constitutively active cell cycle
HPV 16 and 18 have high affinity E7 and can degrade Rb over time (this makes them high risk for cancer)
low risk strains do not degrade Rb
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HPV E6
blocks apoptosis
p53 induces cell cycle arest and apoptosis as a response to overactivation (from E7 action on Rb)
E6 binds E6AP (host protein) which together degrade p53
prevent apoptosis and cycle arrest
high risk strains (like HPV16 and 18) do this at higher rates
E7 turns on cell cycle, E6 deals with the side effects
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how does HPV induce transformation
E7 and E6 block two key chk pts in cell cycle (Rb and p53)
uncontrolled proliferation and loss of ability to apoptose
combination is oncogenic
not an 'objective' of the virus, just wants to replicate itself
cancer only happens in small percent of those infected
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HPV to cervical cancer timeline
HPV incidence inc at start of sexual activity
Dec after marriage/monogamy
Peak of HPV infection happens in teenage years, peak of cancer doesn’t happen until 35-40 yrs old
Transformation after 10 to 15 yrs
215
pathogenesis of cervical cancer
Millions of cases of HPV but only thousands of cancers
Majority are subclinical – low if any symptoms, imm clearance, 16 and 18 not as prevalent
High risk strains can hang on for longer, become more prevalent as time goes on (reverse pyrimid, 'concentration' of the virus in older population bc they are the long lasting ones and don't go away as easily)
normal > low grade neoplasia > high grade neoplasia > cancer
216
neoplasia
bengin tumor
HPV is integrated
217
dysplasia
small bump caused by cells not dying
can be detected on pap smears
HPV is episomal (circular)
218
progression of cervical cancer
normal > dysplasia > neoplasia > cancer
Mild dysplasia – small bump, caused by apical cells not dying, high levels of HPV produced
Moderate and severe – virus is no longer produced, higher levels of E6 and 7, integration of viral DNA into host chromosomes
Invasive carcinoma is the most severe outcome
PROGRESSION TO CANCER CORRELATED W INTEGRATION OF HPV GENOME INTO HOST CHROMOSOME
high risk strains have more integration
219
HPV genome integration
Highly associated w cancer
During DNA rep, ds break, integration event
Can break anywhere in circle
In cancers:
Break in E2 gene, E4 and 5 removed, most of E2 removed
E2 is neg regulator of E6 and 7
Disruption in E2 cannot reg E6 and 7, they become even more active
Grow out of control
220
HPV diagnosis
pap smear (most common)
immunohistochemistry, serology
nucleic acid detection done after previous detection to see if high or low risk strain
221
HPV vaccines
targeted to the L1 of capsids
does not contain any actual virus
given before STI exposure
Gardasil: FDA approved; HPV 16, 18, 6, 11
Cervarix: FDA approval pending; HPV 16, 18
222
HPV treatment (cervical cancers)
freezing, electro‐diathermy, cone biopsy
all to remove cancerous cells
223
how are herpes families organized
cell tropism and genome organization
224
how many human herpes in the family are there
8 or 9
depending on if you separate 6A and 6B
225
chronic vs latent infections
chronic --> constant low level proliferation (HIV)
latent --> does not produce active virus (herpes)
226
herpes virion structure
linear dsDNA
enveloped
icosahedral capsid 200nm
large genome
227
HSV1 tegument
amorphous layer of 14 free proteins
Tegument proteins are released after entry and are crucial for establishing infection
228
HSV1 capsid
icosahedral
6 proteins, VP5 is the major one
229
HSV1 genome structure
dsDNA
Long and short unique regions
Flanked by inverted repeats (mirror ea other: a, b, UL, b’, a’ c’, US, c, a)
A – no ORFs, important for packaging
B - 4 ORFs
C - one ORF
two copies of B and C per genome
replication genes are conserved between diff viruses within the family
GENES ON BOTH STRANDS
some overlap on the same side
230
HSV1 entry
gB and gC bind heparan sulfate proteoglycans on plasma mem
gD binds receptors nectin 1 (ICAM family) and HVEM (TNFR family)
triggers fusion of envelope w cellular membrane via gB, gH and gL
Tegument proteins and capsid are released into the cytoplasm
capsid detaches from tegument
capsid binds at nuclear envelope and insert DNA into nucleus
genome is circularized after entering nucleus
231
HSV1 IE genes
transcribed quickly after infection
do not require new protein synthesis
most are **transactivators of E genes
232
HSV1 E genes
transcribed within 4‐8 hrs
most involved in virus DNA replication
some are transactivators of L genes
233
HSV1 L genes
Vast majority of genes
E‐L or gamma1 genes begin to be transcribed early, but are upregulated after DNA replication
L or gamma2 genes are transcribed only after DNA replication
**most are structural or packaging proteins
234
HSV1 two methods of replication
plasmid (bidirectional) rep:
rolling circle rep:
Result: linear dsDNA in head to tail concatamer
235
HSV1 rolling circle rep
happens 2nd
Head-to-tail concatemer
DNA pol goes in circles
Circle is nicked so that the strand can come off as you roll, allowing continuous rep
Makes long concatemer of linear genomes that are attached to ea other
Another pol comes in to make lagging strand
As more leading is made, more pol comes to make more lagging
Result: linear dsDNA in head to tail concatamer
236
HSV1 plasmid (bidirectional) rep
happens 1st
circular dsDNA, Viral proteins bind strands of genome > ssDNA binding proteins bind to it, another set or proteins come and lay down RNA primer, DNA pol binds RNA primer, extends DNA in both directions, replicates entire circle
Makes more template for later rolling circle rep
237
HSV1 assembly
Immature capsid is assembled by accumulation of VP5 and other proteins around a scaffold
Virus DNA entry into capsid is triggered by packaging sites (a') within the genome
DNA packaging is complete when a full length genome is inserted and the machinery encounters another terminal (a) segment
scaffolding is dismantled and the scaffold proteins are ejected from the capsid
Capsid changes conformation, sealing the DNA inside the capsid
238
HSV1 latency
hallmark of herpes infection
characterized by:
non‐productive infection (no production of infectious virus particles)
maintenance of the viral genome as an episome
few or no virus genes expressed
the ability to reactivate from latency
latency may be established in a diff cell type then primary infection
239
HSV1 spread in body after infection
lytic rep in epithelial cells at site of inoculation
virus enters sensory neurons > retrograde transport
life long latency in neuron
reactivation via anterograde transport
virus reps and sheds from site of lesion (epithelial again)
240
HSV1 vs 2
1 - oral lesions, leading cause of blindness in world (caused by herpes stromal keratitis (HSK))
2 - genital lesions
241
major alphaherpes diseases
Chickenpox
Shingles
Herpes stromal keratitis Oral herpetic lesions
Genital herpetic lesions Encephalitis
242
gammaherpes latency
in B cells
1' inf in epithelial cells and oral cavity
transmitted to BCs in local lymph tissue
BCs circulate in blood, can reactivate at epithelium and be shed
Tibbetts will prob ask about EBV
243
major gammaherpes diseases
(mostly cancers)
Mononucleosis Burkitt’s lymphoma (BL)
B‐cell lymphoma, AIDS‐related Lymphoproliferative disease (PTLD) Peripheral T‐cell lymphoma
Nasal T/NK cell lymphoma
Hodgkin’s disease (HD)
Lymphoepitheliomas (stomach, thymus) Gastric adenocarcinoma Nasopharyngeal carcinoma
Kaposi’s sarcoma
Primary effusion lymphoma
Graft rejection
244
major betaherpes diseases
Birth defects: deafness, blindness, cerebal palsy, mental retardation, physical disabilities, seizures
graft rejection
Pneumonia
245
pox virion structure
linear dsDNA
largest viral genome enveloped ovoid capsid
particle lined w many many proteins, form ridges
Very unusual bi‐concave core that is flanked by lateral bodies
MV = biconcave core + lateral bodies + envelope
EV = MV + extra envelope
246
pox MV vs EV
MV = biconcave core + lateral bodies + envelope
better for cell to cell spread
EV = MV + extra envelope
better for person to person spread (more stable)
bind diff receptors bc EV envelope has diff proteins
247
pox genome structure
dsDNA
v large genome
linear but NO FREE 5' OR 3' ENDS
ea end has terminal loop (hairpin)
genes at ends are repeated twice at the terminal repeats
NO overlapping genes
NO introns --> NO alt splicing
ea gene has its own promoter
genes in both directions
genes named based off of Hind III restriction enzyme digestion
248
key features of vaccinia virus
acts as attenuated smallpox
used in labs (cannot study smallpox in lab)
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