Microbio: Virology Flashcards
what does a naked virus have in it
just the capsid and the nucleic acid
two types of enveloped virus
can have an icosahedral capsid and a helical capsid
what is the envelope on viruses made of?
lipid bilayer
viral recombination
genetic crossing over or exchange of genes between 2 chromosomes within regions of base homology
viral reassortment
this is when viruses with segmented genomes like influenza exchange segments. causes worldwide pandemics like flu
viral complementation
if 1 of 2 viruses that infects a cell has a mutation and can’t a protein, the non mutated virus will help out and get proteins made that are functional and can serve both viruses.
viral phenotypic mixing
this is when two viruses like A and B infect a cell at the same time. if genome A gets coated with viral surface proteins from B, the hybrid virus will have the infectivity of the B virus. However, the progeny from this infection have a type A coat that is encoded by its type A genetic material.
why are live vaccines useful
get humoral and cell mediated immunity
what kind of immune from killed/inactivated vaccines
only humoral immunity
examples of live vaccines
smallpox, yellow fever, chickenpox (VZV), sabin polio virus, MMR, influenza (intra nasal)
examples of killed vaccines
rabies, influenza (injected), salk polio, and HAV vaccines. remember RIP Always
can you give MMR to patients with HIV
Yes- if they do not have signs of immuno-deficiency
recombinant vaccines
HBV (antigen is recombinant HBsAg), HPV (6,11,16,18)
DNA viruses
all are dsDNA except for parvo virus which is “part of a virus” and is ssDNA
DNA viruses- linear or circular
all are linear except papilloma, polyoma and hepadnaviruses
RNA viruses
all are ssRNA except reoviridae (reovirus)
which RNA ssDNA viruses are positive strand:
“I went to a retro toga party where I drank flavored corona and ate hippy California pickles”.
retro virus togavirus flavavirus coronavirus hepevirus calicivirus picornavirus
which naked viral material is infectious
most dsDNA (except poxviruses and HBV) positive stranded ssRNA
which naked viral material is not infectious
naked nucleic acids of negative strand ssRNA and dsRNA are not infectious. they require polymerases contained in the complete virion.
where does DNA virus replicate
in the nucleus (except pox virus)
where does RNA virus replicate
all replicate in the cytoplasm (except influenza virus and retroviruses)
which viruses have envelopes
DNA:
PAPP: papillomavirus, adenovirus, parvovirus, polyomavirus,
RNA:
CPR: Calicivirus, picornavirus, reovirus, and hepevirus.
“give Papp smears and CPR to hippies”
where do enveloped viruses get their envelope
almost all get it from exiting the cell in the cell membrane.
heperpesviruses get it from nuclear material material.
DNA virus characteristics
in general, they are
1) HHAPPPy viruses… hepadna, herpes, adeno, pox, parvo, papilloma, polyoma
2) double stranded (except parvo- ssDNA)
3) are linear (except papilloma, polyoma, hepadna- circular)
4) are icosahedral (except pox- complex)
5) replicate in the nucleus (except pox which carries its own DNA dependent RNA polymerase)
shape of papiloma virus
DNA virus that is an exception to the rule that most are linear. it is CIRCULAR and SUPERCOILED
shape of polyoma virus
DNA virus that is an exception to the rule that most are linear. it is CIRCULAR AND SUPERCOILED
hepadna virus
DNA virus that is an exception to the rule that most are linear. it is CIRCULAR AND INCOMPLETE
features of herpesvirus
DNA, double stranded, linear, enveloped
HSV1
causes mostly oral lesions. some genital
can cause spontaneous temporal lobe encephalitis, keratoconjunctivis
HSV2
genital lesions (some oral)
HSV3
VZV- chicken pox, zoster (shingles), vaccine available
HSV4
EBV- mononucleosis. can also cause Burkitt lymphoma and Hodgkin lymphoma
HSV5
CMV- infection in immunocompromised patients. things like AIDS retinitis, transplant patients, congenital defects
HSV6
roseola (exanthem subitum). usually a fever and then a rash. usually in children
HSV7
less common cause of roseola
HSV8
Kaposi sarcoma
features of Hepadnavirus
DNA, double stranded (partially), circular, enveloped.
disease caused by hepadnavirus
HBV- acute or chronic hepatitis B. vaccine available.
what does the hep B vaccine contain
hep B surface antigen
is hepadnavirus a retrovirus
no, but it contains reverse transcriptase
adenovirus features
non enveloped, double stranded, and linear.
disease caused by adenovirus
febrile pharyngitis, acute hemorrhagic cystitis, pneumonia and conjunctivitis
parvovirus features
non enveloped, single stranded, linear.
which is the smallest DNA virus
parvovirus
disease from parvo virus
B19 virus- aplastic crises in sickle cell disease (bone marrow stops making RBCs), slapped cheeks rash in children, erythema infectiosum (5th disease), RBC destruction in the fetus causing hydrops fetalis and death. pure RBC aplasia and rheumatoid arthritis symptoms in adults.
papillomavirus features
no envelope, double stranded and circular.
Papillomavirus disease
HPV- warts (1,2,6,11), CIN, cervical cancer (16,18), vaccine available
polyomavirus features
No envelope, circular double stranded DNA
polyomavirus diseases
JC virus- can cause progressive multifocal leukoenceophalopathy (PML)
BK virus- transplant patients, commonly targets kidney)
Poxvirus features
Enveloped, double stranded, lienar DNA
largest DNA virus
Pox virus
disease from pox virus
smallpox
cowpox- milkmaid blisters (target like lesions on hand)
molluscum contagiosum- flesh colored dome lesions with central umbilicated dimple
most common cause of sporadic encephalitis in the US
HSV1
where does herpesvirus (HSV1) hang out?
trigeminal ganglia.
how is herpes virus transmitted
respiratory secretions, saliva
which herpes virus causes neonatal herpes
HSV2
where does HSV2 hang out
sacral ganglia
where does HSV3 or varicella zoster hang out
in the dorsal root or trigeminal ganglia
most common cause of complication in shingles
post herpetic neuralgia
how is HSV3 transmitted
respiratory secretions
symptoms of mononucleosis
fever, hepatosplenomegaly, pharyngitis, and lymphadenopathy (especially posterior cervical nodes)
what types of cells does EBV infect
B cells. can see on peripheral smear. when looking at the smear, the atypical cells are reactive cytotoxic T cells.
what is the monospot test
heterophile antibodies detected by agglutination of sheep or horse RBCs
what types of cancer are associated with EBV
Hodgkin lymphoma, Burkitt lymphoma, nasopharyngeal carcinoma
symptoms of mono but negative mono spot test?
CMV infection causing mononucleosis (always has a negative monospot test)
CMV infected cells on histology
classic owl eye where the center is dark, then the white around it and then dark around that.
where does CMV become latent
mono-nuclear cells
Roseola
this is a disease caused by HSV6 or 7. high fevers that last for several days that can cause seizures. then a diffuse macular rash. transmitted by saliva.
Kaposi sarcoma
HSV8. neoplasm of endothelial cells. seen in HIV/AIDS and transplant patients. Dark, violaceous flat and nodular skin lesions which are endothelial growth.
how is HSV8 transmitted
sexual contact
how to test in general for HSV
tzanck test- taking a smear of an opened skin vesicle on a genital wart and looking for multi-nucleated giant cells.
Cowdry A inclusions
can be seen in cells infected with HSV. often the owl eye is associated with CMV
reovirus features
this is a non enveloped, double stranded linear icosaheral capsule.
diseases caused by reoviruses
coltivirus - colorado tick fever
rotavirus- #1 cause of fatal diarrhea in children
picornavirus
non enveloped, single stranded, linear DNA, icosahedral capsule
diseases caused by picornavirus
PERCH: poliovirus echovirus- aseptic meningitis rhinovirus- common cold coxsackie virus - aseptic meningitis, herpangia *mouth blisters, fever), hand foot and mouth disease, myocarditis HAV- acute viral hep A.
hepevirus features
no envelope, single stranded, positive linear, icosahedral shaped capsid
hepevirus diseases
hep E
calciviruse features
no envelope, single stranded, positive linear DNA, icosahedral.
calciviruses disease
norovirus
flavivirus features
enveloped, single stranded positive linear DNA
diseases caused by flaviviruses
HCV, Yellow fever, fengue, St Louis encephalitis, West nile virus
togaviruse fetures
enveloped, single stranded linear positive DNA
toga viruses diseases
rubella, eastern equine encephalitis and western equine encephalitis
retrovirus features
enveloped, single stranded positive linear DNA, can be icosahedral or conical (HIV)
diseases caused by retroviruses
have reverse transcriptase.
HTLV- T cell leukemia (adult T cell leukemia)
HIV
corona viruses
enveloped, single stranded, positive linear DNA, helical capsid
disease caused by corona virus
coronavirus- common cold and SARS
orthomyxovirus fetures
enveloped, single stranded linear, negative DNA (8 segments) helical
diseases caused by orthomyxovirus
influenza virus
features of paramyxovirus
enveloped, single stranded, linear negative non segmented DNA. helical capsid.
diseases caused by paramyxovirus
Parainfluenza- croup
RSV- bronchiolitis in babies, treat with ribavirin
Measles, Mumps
rhabdovirus fetures
enveloped, single stranded, negative linear, helical capsid
disease from rhabdovirus
rabies
filovirus features
enveloped, single stranded, linear DNA negative, helical capsid
diseases from filovirus
ebola/marburg hemorraghic fever- often fatal
arenavirus features
enveloped single stranded, negative, circular DNA in 2 segments. helical capsid
disease caused by arenavirus
LCMV- lymphocytic choriomeningitis virus
Lassa fever encephalitis- spread by mice
bunyaviruse features
enveloped, single stranded, circular 3 segments, helical capsid.
diseases caused by bunyaviruses
california encephalitis, sandfly/rift valley fever, crimean congo hemorrhagic fever, hantavirus
delta virus features
enveloped, single stranded, negative circular, uncertain capsid
disease caused by delta virus
HDV - defective virus that requires HBV co infection
how does a negative stranded virus work?
it must take the negative strand and then transcribe a positive strand to go with it. virion brings it own RNA dependent RNA polymerase to do this.
pneumonic for negative stranded RNA viruses
Always Bring Polymerase Or Fail Replication Arenyvirus Bunyavirus Paramyxovirus Orthomixovirus Filovirus Rhabdovirus
Which RNA viruses are segmented
BOAR Bunyavirus Orthomyxovirus (influenza) Arenavirus Reovirus
how does picornovirus work?
so this gives polio, echovirus, rhinovirus, coxsackie virus and HAV.
RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins. can cause aseptic viral meningitis (echovirus), meningitis. all except rhinovirus are fecal-oral spread
rhinovirus
this is a type of picornavirus that is a single stranded RNA non enveloped virus. common cause of the common cold. has >100 serologic types. acid labile- destroyed by acid in stomach so never get GI infection
Yellow fever
you get this from flavivirus.
how is yellow fever transmitted
aedes mosquitos
reservoir for yellow fever
monkey or human
symptoms of yellow fever
high fever, black vomit and jaundice
rotavirus
this is a type of reovirus, which is a non enveloped, double stranded RNA virus. most important cause of global diarrhea in infants.
when do you see rotavirus infections
in the US- cause of acute diarrhea in day care centers, kindergartens especially in the winter
damage to the body done by rotavirus
decreased absorption of Na and loss of K
influenza
caused by the segmented, enveloped, negative single stranded RNA virus orthomyxovirus. 8 segment genome.
viral features of influenza virus to help it enter cells
contains hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release). rapid genetic changes can be see
what is an issue with influenza which explains pandemics
genetic or antigen shift. segments undergo high frequency recombination. sudden shift= deadly
genetic shift of influenza causes…
pandemics
genetic drift of influenza causes…
epidemics
genetic drift of influenza
this is more minor changes based on random mutation
rubella
this is from the togavirus which is an enveloped, single stranded positive linear RNA virus.
rubella symptoms
fever, postauricular (right behind the ear) and other lymphadenopathy, and fine rash. rash starts with fine macules on the face and spreads to involve trunk and extremities
rubella disease that is congenital
much more serious that regular rubella. it causes “blueberry muffin” appearance rash.
croup
caused by paramyxovirus- enveloped, negative single stranded rna. specifically caused by parainfluenza virus
how do paramyxoviruses infect respiratory system
all contain a surface F or fusion protein which causes respiratory epithelial cells to fuse and form multinucleated cells.
use of Palivizumab in infants
this can be used to bind to the F protein and prevent pneumonia caused by RSV (respiratory syncicial virus) infection in premature infants. this is a type of paramyxovirus.
measles caused by…
this is caused by the paramyxoviruse.
classic exam findings in measles
Koplik spots (red spots in the mouth with a white or blue center) and descending maculopapular rash. spreads downward and includes the limbs (can distinguish from rubella).
possible sequelae of measles
sub acute sclerosing panencelphalitis, encephalitis, and giant cell pneumonia
3 C’s of measles
cough, coryza (runny nose), conjunctivitis
mumps is caused by…
caused by a paramyxovirus
symptoms of mumps…
parotitis (inflamamtion of parotid glands), orchitis (inflammation of testes) and aseptic meningitis.
sequelae of mumps if not treated
can cause sterility, especially after puberty
rabies is caused by…
this is caused by the rhabdovirus, which is a single stranded, enveloped, negative linear RNA virus
histologic findings in rabies
bullet shaped virus with negri bodies found in Purkinje cells of cerebellum and in hippocampal neurons.
does rabies have a short or long incubation period
long
treatment after a bite for rabies?
wound cleaning and rabies vaccine as well as possible rabies immunoglobulin
how does rabies get to the brain
travels up to the CNS by migrating in a retrograde fashion up nerve axons
early signs of rabies
fever, malaise
classic later signs of rabies
agitation, photophobia, hyrophobia (patient is thirsty, but when presented with water they freak out and refuse to drink or swallow it but they can’t quench their thirst), then can cause paralysis and coma/death
how do you get a rabies infection
bat, raccoon and skunk bites. less from dog bites in the US
symptoms of any hepatitis virus
jaundice, fever, increase ALT, AST
what type of virus causes HepA
RNA picornavirus
what type of virus causes HepB
DNA hepadnavirus
what type of virus causes HepC
RNA flavavirus
what type of virus causes HepD
RNA delta virus
what type of virus causes HepE
RNA hepevirus
which hepatitis viruses are oral-fecal
Hep A and Hep E
which hepatitis viruses are parenteral
Hep B, C, D
which hepatitis virus is commonly associated with blood transmission
HepC
which hepatitis viruses can induce a carrier state?
B, C, D
which types of hepatitis increase risk for hepato-cellular carcinoma
Hep B, C, D
which Hepatitis virus depends on another one for infection
Hep D is a defective virus and requires HepB infection either at the same time or previously
which of the hepatitis types are naked
Hep A: picornavirus
Hep E: hepevirus.
becuase they are naked, they do not rely on an envelope and are not destroyed in the stomach
DNA polymerase in HepB
it is special. it has both DNA and RNA dependent activities. when it enters the nucleus, the polymerase functions to complete the partial dsDNA. the host RNA polymerase transcribes mRNA from viral DNA to make viral proteins. the DNA polymerase then reverse transcribes viral RNA to DNA to form new viral packets.
best test to detect hepA
anti HAV (IgM)
presence of anti HAV (IgG)
means either previous infection or vaccination
HBsAg
means active hepB infection
HBsAb
means antibody and immunity to hep B
HBcAg
this is the core antigen. it is present if they were ever infected but NOT if immunized.
IgM core antigen for hep B
means acute HBV or window period
IgG core antigen for hep B
means chronic infection or recovery
HBeAg
this is a different antigen- the envelope antigen- indicates active viral replication and therefore high transmissibility
antiHBe
this is an antibody to the envelope. indicates low transmissibility
lab findings if immunized for Hep B
only one thing shoudl be positive- antibody to Hbs. antibody to the surface antigen.
envelope antigen is present in which stages
acute and chronic with high infectivity
envelope antibody (anti-HBe) is present in which stages
window, chronic HBV with low infectivity and recovery
HIV
caused by retrovirus which is an enveloped, single stranded positive linear DNA with conical capsid
3 structural genes in HIV
1) env: forms gp120 and gp 41. 120 is for attachment to host CD4 T cells and 41 is for fusion and entry
2) gag : p24- capsid protein
3) pol - reverse transcriptase, aspartate protease, integrase
why does HIV need a reverse transcriptase
it has an RNA genome and the reverse transcriptase synthesizes dsDNA from the RNA and this dsDNA gets incorporated into the host genome
gp120 and gp41 proteins in HIV
these are proteins that are envelope proteins. gp120 is for attachment to CD4 cells and gp41 is for fusion and entry into the cells. these proteins are acquired through budding from host cell plasma membrane.
what does HIV virus bind to for T cell entry?
early in disease: CCR5
late in disease: CXCR4
both: binds CD4 as well to get into T cells
what does HIV bind to for macrophage entry?
CCR5 and CD4 on macrophages
mutation in CCR5 and its relation to HIV?
immunity if homozygous and slow disease progression is heterozygous
how to diagnose HIV
early diagnosis is made with an ELISA which has a high sensitivity and a low specificity- lots of false positives. confirmation test with Western blot assay- very specific.
HIV PCR test- what does it tell you
tells you the viral load to determine the amount of viral RNA in the plasma. can monitor drug therapy with this. high viral load= poor prognosis
definition of AIDS diagnosis
CD4 <200
HIV positive with AIDS defining illness
HIV positive with AIDS defining illness such as pnemocystis pneumonia. or CD4 percentage <14 percent
what does the elisa or Western blot look for in HIV test
looks for antibodies to viral proteins. can be false negative in the first 1-2 months after HIV infection and false positive in babies born to infected mothers
why do newborns often have a positive HIV test right after delivery even if not infected with HIV
anti gp120 antibodies can cross the placenta
where does HIV replicate during the latent phase
in the lypmh nodes
low grade fever, cough, tongue ulcer and hepatomegaly in an HIV patient…
think about histoplasma capsulatum infection. see oval yeast cells within macrophages
fluffy white cottage cheese lesions in mouth and esophagus in HIV patients
think about C albicans. usually get oral thrush with CD4 around 400 and esophageal infection with CD4 <100
Hairy leukoplakis on lateral tongue in HIV patients
EBV infection
superficial vascular proliferation with neutrophils in HIV patient
Bartonella henselae (bacillary angiomatosis). side note- kind of looks like Kaposi sarcoma
chronic watery diarrhea in HIV patient
cyrptosporidium infection. acid fast cysts seen in stool
neurologic absecess with ring lesions that enhance on MRI in an HIV patient
toxoplasma gondii
encephalopathy in an HIV patient
think about JC virus
meningitis in an HIV patient
think about cryptococcus neoformans. india ink stain will reveal yeast with narrow based budding
retinitis in HIV patients with cotton wool spots on fundoscopic exam
CMV infection. may see esophagitis with it
non hodgkin lymphoma (large cell type) on the oropharynx (waldeyer ring) in an HIV patient
think about EBV
primary CNS lymphoma in HIV patient
rule out toxoplasma. can be associated with EBV
squamous cell carcinoma of the anus in HIV patient
HPV infection
superficial proliferation of vasculature (neoplastic with lymphocytic inflammation) in HIV patient
this is HHV 8 or Kaposi sarcoma. make sure to differentiate from above infection with Bartonella henselae giving bacillary angiomatosis.
interstitial pneumonia with owl eye inclusion bodies in HIV patient
CMV
pleuritic pain, hemoptysis, infiltrates on imaging in HIV patients
aspergillus fumigatus infection
pneumocystis pneumonia- ground glass appearance on imaging, CD4< 200 in HIV patient
Pneumocystic jirovecii. CD4<200
pneumonia with CD4>200 in HIV patient
Strep pneumoniae
tuberculosis like disease with CD4<50 in HIV patient
think about mycobacterium avium intracellular also known as MAC
sporadic prion disease
Creutzfeld Jakob disease- rapidly progressive dementia
inherited prion disease
Gerstmann straussler scheinker syndrome
acquired prion disease
kuru
