RNA Viruses Flashcards
what is the smallest RNA virus
picornavirus
What is the structure of picornavirus
Naked, + icosahedral ssRNA
Where does picornavirus replicate?
cytoplasm
what is the picornavirus capsid made of?
60 copies of NON-GLYCOSYLATED proteins
how does picornavirus enter the cell?
receptor-mediated endocytosis
What does a + genome mean?
the genome acts as mRNA
What does a - genome mean?
the genome is complementary to the mRNA that will eventually be made
What are picornaviruses released from the cell?
cell lysis
What does poliovirus use as a receptor?
PVR/CD155
What do most other picornaviruses use as a receptor?
ICAM-1
What part of the picornavirus capsid binds to the receptor?
canyon region
What else can bind to the picornavirus canyon regions?
Antibodies to neutralize virus
What is unique about the protein made by picornavirus?
It is translated as 1 protein, and cleaved by a VIRAL PROTEASE
What are (-) copies made by picornaviruses?
complementary template used to make more copies of the viral genome
What is found at the 5’ end of picornavirus RNA?
VPg
What is cleaved terminally in picornavirus replication? what is made?
VP0 –> VP2 and 4 mature particles
What is VPg?
virally encoded protein that acts as a 5’ cap; guides translation and packaging of proteins
How is picornavirus transmitted?
Fecal-oral
Respiratory droplets
What is unique about rhinoviruses?
They are LABILE at acidic pH; like the upper airway
What is unique about the other enteroviruses?
STABLE at acidic pH, like the GI tract
What are the examples of the picornavirus family?
Poliovirus Enterovirus Rhinovirus Coxsackie A and B Hepatitis A
What is the most common cause of the common cold ?
Rhinovirus
Where do enteroviruses replicate?
mucosa and lymphoid tissue of tonsils and pharynx
M cells and lymphocytes of Peyer’s patches
Enterocytes of intestinal mucosa
What causes the spread of virus to secondary tissues?
Primary viremia
What determines the degree of paralysis in paralytic polio?
the type of neurons affected and degree of damage
Who is more severely affected by paralytic polio?
the young and elderly
What are the effects of spinal cord involvement in paralytic polio?
paralysis of limbs or complete flaccid paralysis
What is affected in bulbar paralysis?
cranial nerves and the respiratory center in the medulla
Where is replication of poliovirus restricted to?
GI tract
What are the symptoms of poliovirus?
Could be asymptomatic
Could range from mild fever w/ diarrhea to FLACCID PARALYSIS
What does poliovirus infect?
ANTERIOR horn cells of the spinal cord and the MOTOR cortex
What are the vaccines for polio?
Salk -Inactivated vaccine (intramuscular)
Sabin- Live attenuated (oral) [CAN REVERT]
How many doses of polio vaccine are given?
4
What does coxsackie A cause?
herpangina
Hand, foot, and mouth disease
What is herpangina?
painful ulcers found in the mouths of young children
What is hand, foot, and mouth disease?
vesicular lesions of the hand, feet, and mouth
What does echovirus cause?
aseptic meningitis
What does parechovirus cause?
GI and respiratory infection
encephalitis, myocarditis
What does kobuvirus cause?
GI infections
What does coxsackie B cause?
myocardial and pericardial infections
When does enterovirus aseptic meningitis normally occur?
Summer and early fall
What is the most common cause of viral meningitis?
Enteroviruses
Most common culprits of viral conjunctivitis?
Coxsackie A24
Enterovirus 70
Most common culprits of hand,foot,and mouth disease?
Coxsackie A16
Enterovirus 71
How are enteroviruses diagnosed?
Antibodies(IgG or IgM) or viral RNA through RT-PCR
What do rhinoviruses attach to on the cell?
ICAM-1
Where is a rhinovirus infection most commonly found?
UPPER Respiratory tract
What mediates rhinovirus immunity?
IgA (can have re-infection)
How many Hep A serotypes are there?
ONE
How is Hep A transmitted?
Fecal-oral
Where does Hep A replicate?
enteric mucosa
When do Hep A symptoms arise?
AFTER excretion
What is a prodrome?
set of early symptoms that may indicate a disease is present before specific symptoms arise
What is part of the prodrome of Hep A?
Dark urine, clay colored stool
What are symptoms of the icteric stage of Hep A?
jaundice, pruritis, tender hepatomegaly
What is unique about Hep A infections?
Most will be ASYMPTOMATIC
What labs can diagnose acute Hep A infections?
Increased ALT
+ IgM anti Hep A test
Needed for Hep A diagnosis?
Hep viral serologies, liver ultrasound
Where is Hep A primarily found?
Developing countries
What is the vaccine for Hep A?
Inactivated whole virus vaccine
What viruses cause Gastroenteritis?
Caliciviruses
Astroviruses
Rotaviruses
Adenoviruses
What is the structure of the calicivirus
Naked, + icosahedral ssRNA
What is the primary agent responsible for most acute dirrheal diseases in adults and children?
Norovirus
Where is calicivirus commonly found?
Cruise ships and day care (causing DIARRHEA)
How is norovirus transmitted?
person to person
Fecal-oral
aerosol transmission from vomiting
What is unique about the virus particles of noroviruses?
Not many are needed to infect!
What is the pathogenesis of noroviruses?
infection of epithelial cells in the stomach/intestine leads to maldigestion
What is unique about astroviruses?
it cannot be grown on cell culture
What is the structure of reoviruses?
Naked, + icosahedral dsRNA
What are the 2 types of reovirus?
Rotavirus
Colorado tick fever
What is the leading cause of severe acute gastroenteritis in children worldwide?
Rotavirus
How many rotavirus serotypes are there?
5 (G1, G2, G3, G4, G9)
How is rotavirus transmitted?
Fecal-oral (VERY STABLE)
What does rotavirus replicate?
villous epithelium of the small intestine
What is an important treamtent for rotaviruses
REHYDRATION THERAPY
How is rotavirus diagnosed?
detection of virus particles or viral antigens in stool
What are vaccines for rotavirus?
RotaTeq and Rotarix (both oral live virus vaccine)
Antibodies to what are important for rotavirus protection?
VP7 and VP4
What has rotavirus vaccines been associated with?
intussusception
What are the symptoms of Colorado tick fever?
fever, headache, sever myalgia
How many segments does Colorado tick fever have?
12 dsRNA segments
What is the structure of Hep E?
Naked, + icosahedral ssRNA
How is Hep E transmitted?
fecal-oral
What is a major cause of acute hepatitis worldwide?
HEV
What is Hep E primarily associated with?
poor sanitation
What kind of disease is Hep E?
ACUTE only
Who is most likely to have fulminate symptoms from Hep E?
pregnant women
Hep E symptoms are most common among who?
adolescents, young adults, and pregnant women
What is IgG associated with?
long term immunity
What is IgM associated with?
acute infection
What is IgA associated with?
mucosal immunity
What are some viruses causing CNS disease and hemorrhagic fever?
Togaviruses
Flaviviruses
Bunyaviruses
Arenviruses
What are arboviruses?
arthropod-borne viruses
What is the structure of togaviruses?
Enveloped, + icosahedral ssRNA
How do togaviruses enter the cell?
receptor-mediated endocytosis
What are the genuses of togaviruses?
Alphaviruses and Rubiviruses
Where do alphaviruses replicate?
cells of arthropod vectors and vertebrae host
What is the natural host of alphaviruses?
mammal or bird
How are alphaviruses transmitted?
FEMALE mosquitos
Where is the alphavirus transmitted from?
salivary gland of mosquito to capillary bed
Types of alphaviral encephalitides
Easter, Western, and Venezueland equine encephalitits
How are arboviruses diagnosed?
virus specific IgM and neutralizing antibodies in serum or CSF
What is the most severe equine encephalitis?
EASTERN
What is the reservoir of VEE? for EEE and WEE?
Rodents. Birds
What is Chickungunya Fever virus?
debiliating illness with high fever, petechial or maculopapular rash, headache, fatigue, nausea, vomiting, muscle and joint pain
Where does Chickungunya fever virus replicate?
fibroblasts, skeletal muscle progenitor cells, myofibers
Most common lab finding of Chikungunya?
elevated creatinine, AST, and ALT
What is the treatment for Chikungunya fever virus?
There is none.
How is Chikungunya transmitted?
mosquitoes (A. aegypti, A albopictus)
How is Chikungunya diagnosed?
Serological IgM/IgG
RT-PCR
What is the structure of flaviviruses?
Enveloped, + icosahedral ssRNA
What kinds of diseases do flaviviruses cause?
encephalitis and hemorrhagic fevers
What flaviviruses cause hemorrhagic fever?
Dengue
Yellow fever
How is yellow fever transmitted?
mosquitos
What are the symptoms of yellow fever?
MOstly asymptomatic
Can have flu-like symptoms with jaundice, GI hemorrhage, and BLACK vomit
What is the vaccine for yellow fever?
Live attenuated 17D vaccine
What is the most widespread arbovirus in the world?
Dengue fever
How many serotypes of Dengue fever are there?
- multiple reinfections possible
How is Dengue fever transmitted?
mosquitos
What are the symptoms of Dengue fever?
severe headache, muscle and joint pain, leukopenia, thrombocytopenia
Where does Dengue fever replicate?
mononuclear cells
What is a nickname for Dengue fever?
Breakbone fever
What is Dengue Hemorrhagic fever?
occurs with re-infection with a different Dengue fever serotype
What is the treatment for Dengue Hemorrhagic fever?
Treat the symptoms.
IV fluids, electrolytes, Oxygen, rehydraton
What are some Flaviviruses that cause encephalitis?
Powassan virus STL encephalitis West Nile fever Japanese B encephalitis Murray valley fever
What is unique about Powassan virus?
it is TICK borne
What is POW encephalitis associated with?
long-term morbidity
Clinically, West nile virus can be what?
Non-neuroinvasive or neuroinvasive
How can West nile be transmitted from human to human?
Blood transfusions
Transplanted organs
Breast milk
Transplacentally
What test is used by blood banks to check for West Nile?
Nucleic acid Amplification Test
How can West Nile be diagnosed?
testing serum/CSF for WNV specific IgM antibodies
viral cultures and RT-PCR
What is the treatment for West nile?
There is no treatment.
What are some arbovirus Bunyaviruses?
California encephalitis virus and RIft valley fever
How is California encephalitis transmitted?
mosquitoes
How is Rift valley fever transmitted?
mosquitoes and sandflies
What does Hantavirus cause?
Hemorrhagic fever and pulmonary syndrome
When does California encephalitis peak?
summer months
Influenza is a member of what family?
Orthomyxovirus
What is the structure of orthomyxoviruses?
Enveloped, - HELICAL segmented ssRNA
What are the major types of influenza
A, B, C
How many gene segments do Influenza A and B have?
8
What proteins are found in the surface of the influenza virus?
Hemagglutinin and Neuraminidase
What is significant about the M2 protein?
Needed to get the genome OUT
What does hemagglutinin bind?
sialic acid
How many HA subtypes are there?
18
What is HA1 used for?
attachment
What is HA2 used for?
fusion
What is neuraminidase used for?
cleaving sialic aicd during release of viruses
Hemagglutinin is a…
TRIMER
Neuraminidase is a…
TETRAMER
Which part of the orthomyxovirus is a target for drugs?
Neuraminidase
Tamiflu, Relenza
Where is HA0 protein cleaved?
Respiratory epithelium
What causes the conformational rearrangement in HA
pH drop in the endosome
Where are alpha (2,3) linkages cleaved?
LOWER Respiratory tract
avian influenza virus
Where are alpha(2,6) linkages cleaved?
UPPER Respiratory tract (human influenza virus)
What is unique about the HA protein?
high degree of variability
virus in is NOT the same virus out
Where does the HA variability come from?
No exonuclease activity in RNA polymerase
What is a quasi-species?
not a clone, but a mixture that undergoes selection, has a variety of genotypes
Where does orthomyxovirus replicate?
Nucleus ( in order to use the 5’ caps of host mRNA)
How is orthomyxovirus transmitted?
large-particle respiratory droplets
Where does influenza multiply?
ciliated respiratory epithelium cells
Where is the influenza virus limited?
respiratory tract
What is a complication of influenza infection?
invasive bacterial superinfection
What is unique about the association between bacterial pathogens and influenza?
Bacterial pathogens can readily adhere to the surface of influenza-infected cells
What does recovery from influenza infection begin with?
IFN production
When does influenza peak?
winter months
What is shift?
SUDDEN, emergence of NEW subtypes
Little or no herd immunity
What is drift?
INCREMENTAL, emergence of VARIANT subtypes
Mutations cause evasion of herd immunity
What was the most devastating outbreak in human history?
Spanish Flu
Is drift or shift associated with increasing the world death rate?
SHIFT.
What percentage of the population gets the flue each year?
5-20%
What are the influenza vaccines?
Inactivated injection
Live attenuated nasal spray
Which influenza vaccine is QUADRIVALENT only?
Nasal spray
Influenza vaccines are normally grown in what?
eggs
What influenza vaccine is okay for people with egg allergies?
Trivalent vaccine grown in cell culture
Who is the high dose trivalent vaccine used for?
the elderly (4x antigen)
Who is the nasal spray vaccine recommended for?
Healthy people 2 through 49 that are not pregnant
How do zanamivir and oseltamivir work?
inhibits neuraminidase
What is another name for zanamivir?
Relenza
What is another name for oseltamivir?
tamiflu
How do amantidine and rimantidine function?
target the M2 ion channel and block fusion
How is influenza diagnosed?
By looking at the viral antigens
What are some complications of influenza vaccines?
Guilian-Barre syndrome
Reye’s syndrome
Which bird flu has never been detected in peopl?
H7N9
What would cause bird flu to become a Human pandemic virus?
Better binding by HA
Better replication
Better processing of viral RNAs and proteins
Person-person transmission
What is a necessary precondition for a virus to be pandemic?
PERSON TO PERSON TRANSMISSION
What is the structure of paramyxoviruses?
Enveloped, - helical ssRNA
Who is mostly affected by Respiratory syncytial virus?
infants and elderly
Who is mostly affected by parainfluenza?
young children (Croup)
What does metapneumovirus cause?
acute respiratory disease
What is the structure of RSV?
enveloped w/ 2 envelope glycoproteins
What is the G glycoprotein of RSV for?
Attachment
What is the F glycoprotein of RSV for?
Fusion
What is the single most important cause of respiratory diseases in infancies?
RSV
What does RSV infect?
Upper and lower respiratory tract
RSV is localized where?
Respiratory epithelium
What drug is targeted as the F protein of RSV
Palivizumab
What does Palivizumab target?
F protein of RSV
How many parainfluenza serotypes are there?
4
What is unique about each of the 4 parainfluenza serotypes?
There are antigenically stable.
What are parainfluenza viruses?
Enveloped paramyxoviruses with HA and NA on the SAME SPIKE
Parainfluenza viruses can cause what kind of illness?
Upper and Lower respiratory illnesses
Which parainfluenza viruses are most often associated with croup?
HPIV-1 and HPIV-2
What is HPIV-3 associated with?
bronchitis, bronchiolitis, and pneumonia
RSV is more associated with what disease?
Bronchiolitis
Parainfluenza is more associated with what disease
Croup
How is parainfluenza transmitted?
Person to person
What is another name for measles?
Rubeola
What is another name for mumps?
epidemic parotitis
What type of vaccine is the MMR vaccine?
Live attenuated
Where does measles replicate?
upper respiratory tract
Symptoms of measles
Cough, Coryza, Conjunctivitis, Koplik’s spots on buccal mucosa
How is mumps transmitted?
Respiratory transmission
Where does mumps initally replicate?
Respiratory tract epithelium and local lymph nodes
Where does mumps disseminate to?
salivary glands and CNS
What are some complications of mumps?
meningitis, encephalitis, pancreatitis, orchitis, oophoritis
What is orchitis?
most common complication in postpubertal males. Inflammation of epididymis
What is the structure of togaviruses?
Enveloped, + icosahedral ssRNA
How is Rubella transmitted?
respiratory droplets
Transplacentally
Where does rubella replicate? Where does it disseminate?
Upper respiratory tract
Lymphoid tissue, skin, organs
When during pregnancy is fetus at risk for rubella damage?
1st trimester
What is the treatment for measles, mumps, and rubella?
There is no treatment, BUT THERE IS A VACCINE MMR
What are some zoonotic paramyxoviruses?
Hendra and Nipah
What is the structure of a coronavirus?
Enveloped, + ssRNA, w/ spike-like glycoproteins
What are some examples of zoonotic coronaviruses?
SARS, MERS
What are the 2 main virusese of the Rhabdovirus family?
Rabies and Vesicular Stomatitis virus
What is the structure of a rhabdovirus?
Enveloped, - helical ssRNA with a bullet-shaped capsid
Where does rabies multiply?
brain
What are the phases of a rabies infection?
Prodrome
Neurologic
Comatose
What is the treatment for rabies?
THERE IS NO ANTIVIRAL TREATMENT, BUT THERE IS A VACCINE
What is the rabies vaccine?
Human Diploid Cell Vaccine (inactivated, gives active immunity)
When is it best to vaccinate someone for rabies?
When they think they have been exposed to it
How is rabies transmitted?
saliva of infected animals through a bite
How is rabies diagnosed?
Watching for clinical changes in the animal
Negri bodies in the brain (cytoplasmic inclusions)
How is rabies diagnosed in humans?
RT-PCR of saliva
anti-rabies Abs in serum/spinal fluid
biopsy of hair follicles from nape of neck
What is the Rabies prophylactic treatment?
1 dose of immunoglobulins and 4 doses of rabies vaccine over a 14-day period
How is Human Diploid Cell Vaccine made?
in tissue culture using normal human WI-38 fibroblasts. The rabies virus is then inactivated
What is the only non-arboviric Bunyavirus?
Hantavirus
How many segments does Hantavirus have?
3
What are the 2 different manifestations of hantavirus?
Hemorrhagic fever w/ renal syndrome
Hantavirus pulmonary syndrome
What hantavirus type causes Hemorrhagic fever w/ renal syndrome
Old world Hantaviruses
What hantavirus type causes hantavirus pulmonary syndrome?
New World Hantaviruses
Where is hantavirus found in infected rodents?
urine and feces (rodents are not sick)
How is hantavirus transmitted?
aerosolized rodent excreta
How is Hantavirus pulmonary syndrome caused?
an inflammatory response against infected tissues
What is the structure of an arenavirus?
Enveloped, - helical segmented ssRNA
What is unique about arenaviruses?
they have TWO separate nucleocapsids surrounding the 2 segments of RNA
What are some diseases caused by arenaviruses?
Lymphocytic choriomeningitis virus and Hemorrhagic fevers
Where are arenaviruses shed?
urine and droppings of infected hosts
How are arenaviruses transmitted?
contact with excretions of infected rodents
some person-person transmission
How does LCMV present?
aseptic meningitis, encephalitis, or meningioencephalitits
A transplacental LCMV infection is associated with what?
congenital hydrocephalus
Chorioretinitis
mental retardation
What is the primary host of LCMV?
Mus musculus (house mouse)
What disease does Lassa virus cause?
African Hemorrhagic fever (Lassa fever)
What disease does junin virus cause?
Argentine hemorrhagic fever
What disease does Machupo virus cause?
Bolivian hemorrhagic fever
What disease does Guanarito virus cause?
Venezuelan hemorrhagic fever
What disease does sabia cause?
Brazilian hemorrhagic fever
What groups are particularly at risk of death with arenavirus hemorrhagic fevers?
Fetuses with transplacental infections and women in the 3rd trimester
What are some symptoms of arenavirus hemorrhagic fever?
fever hemorrhagic manifestations hepatitis shock neurological manifestations
What is the last ditch effort against RNA viruses?
Ribavarin
What is the structure of a fillovirus?
Enveloped, - helical ssRNA
What are some examples of filoviruses?
Ebola, Marburg
What is the most likely reservoir of ebola?
fruit bats
Most likely source of zoonotic ebola infection
bushmeat
What are the first symptoms of filovirus infection?
sudden onset of flu-like symptoms
What cells are infected by filovirus infection?
lymphoid and endothelial cells
What causes death in a filovirus infection?
hypovolumic shock, multi-organ failure
What is the pathogenicity of RNA viruses associated with?
cross species jump
What is the most likely reason for virus spread?
increased, rapid, international travel
What is the structure of a flavivirus?
Enveloped, +icosahedral ssRNA
What family is Hep C a part of?
Flavivirus
What does HCV exist as?
A quasispecies
Where is antigenic variation predominnat in HCV
envelope glycoprotein E2
enables escapes and persistant infection
What is the most common chronic blood-borne infection in the US?
HCV infection
Who is Hep C screening recommended for?
People born between 1945-1965
History of IV drug use
How is HCV transmitted?
Percutaneous exposures to infectious blood sex(infrequent)
Trans-placentally
What are some symptoms of an acute HCV infection?
fever, fatigue, dark urine, clay-colored stool, abdominal pain, loss of appetite, nausea, vomiting, joint pain, and jaundice
Where does the initial replication of HCV occur?
monocytes, B ant T cells
What is unique about HCV disease?
Infection is usually mild and anicteric, but results in a chronic carrier state in a majority of people
How long is IgG anti HCV found in an infected individual?
For life.
What is a host factor that may improve clearance of HCV?
IL-28B gene plymorphisms
Chronic HCV disease has what kind of disease progression?
Insidious
What are some complication of chronic HCV disease?
Cirrhosis
Hepatocellular carcinoma
What is the leading cause of liver transplants in the US?
Chronic HCV Disease
HCV is mainly an ______-mediated dissease
Immune (cytokine storm)
What allows HCV to escape the immune system?
Viral mutations from its quasispecies nature
How does HCV target the immune response?
HCV core binds host’s TNF receptor
Are Hep C antigens for in the blood?
NO. antibodies are
How is HCV diagnosed?
Anti- HCV using ELISA
HCV RNA using Nucleic Acid Test
What are some treatments for HCV?
protease inhibitors (telaprevir, boceprevir, simeprevir)
nucleotide inhibitors (sofosbuvir)
What are the 4 families of retroviruses?
LOSE: Lentiviruses Oncoviruese Spumaviruses Endogenous retroviruses
What are human endogenous retroviruses (HERVs)?
retrovirus sequences that have been integrated into the human genome
Do HERVs produce infectious particles?
No. but can encode some functional proteins
What is HERV-W?
functional envelope protein expressed in human placenta (syncytin protein); needed for creation and maintainence of syncytiotrophoblast
How do retroviruses work?
they beome part of the host DNA
What does reverse transcriptase do?
converts ssRNA into ssDNA, and then into dsDNA
allows for integration of viral genome into host DNA
What is the structure of a retrovirus?
Enveloped, + icosahedral with 2 IDENTICAL COPIES of ssRNA
What is unique about retroviruses?
They do not directly code for protein, they will be reverse transcribed into DNA
What is gag for in the retroviral genome?
encodes capsid, nucleocapsid, and matrix proteins
What is pol for in the retroviral genome?
encodes the reverse transcriptase, protease, and intergrase
What is env for in the retroviral genome?
encodes surface and transmembrance proteins
What is LTR for in the retroviral genome?
Long terminal repeats. These bind cellular and viral transcription factors
Where does reverse transcriptase do its job?
Cytoplasm
What incorporate the newly made viral dsDNA into the host DNA
LTRs and intergrase
What must occur for a mature infectious virus to occur?
cleavage of gag-pol precursors on budding immature particles
Is the new dsDNA linear or circular before it is integrated into the host genome?
circular
What is a provirus?
DNA copy with LTR integrated into the host
What is an example of a Spumavirus?
Human foamy virus
Is spumavirus considered pathogenic.
Nope.
What are oncoviruses?
retroviruses that can immortalize or transform cells
What important about oncoviruses in relation to cancer?
they may contain growth-regulating oncogenes that if overproduced or altered stimulat cell growth, causing tumors
What is the only human oncovirus?
HTLV
What can HTLV-1 cause?
Adult T cell leukemia and Tropical spastic paraparesis
Where is HTLV-1 endemic?
Southern japan and the carribean
How is HTLV-1 transmitted?
Sex
mother-to-infant (breastfeeding)
[requires cell-to-cell contact]
What is important about Tropical Spastic Paraparesis?
It is a non-neoplatic neurologic disorder
What does HTLV-1 contain?
tax, binds in LTR to promote viral replication
What are flower cells?
multi-lobulated lymphocytes that are seen in patients with ATLL
In what group is HTLV-II prevalent?
IV drug users
How are HTLV viruses diagnoses?
ELISA to find anitbodies against viral antigens
What is another name for Tropical Spastic Paraparesis?
HTLV associated myelopathy (HAM)
How is ATLL treated?
anti-cancer therapy
How is HAM treated?
anti-retrovirals
What genomic elements is found in all retroviruses?
tax
How do lentiviruses progress?
slowly
What do lentiviruses cause?
neurological disorders and immunosuppression
What are some examples of lentiviruses?
HIV-1 and HIV-2
What is unique about the HIV virion
it has a coffin-shaped capsid
Which of the 2 HIV viruses is less virulent?
HIV-2
What parts of HIV-1 and HIV-2 cross react? What parts don’t?
Caspid antigens.
Envelope antigens.
Which HIV virus predominates in most of the world?
HIV-1
How do the products of gp160 precursor protein interact?
gp120 (globular head) associates with gp41 (stem)
How dogp120 and gp41 interact?
noncovalently
How many potential N-linked glycosylation sites are there?
30-38
How does HIV bind?
gp120 binds to CD4, inducing a conformational change
This changes allows gp120 to bind CCR5/CXCR5
gp41 can then initiate fusion
How asre TAT, REV, and NEF made?
splicing
What is tat?
protein that is a positive regulator of transcription
What is rev?
protein that regulated expression of viral mRNA for structural genes
What is nef?
protein needed for high levels of virus associated with disease progression; down regulates CD4 and MHC class I
What is required for HIV-1 replication in primary cells?
vif
How does vif function?
inhibits APOBEC-3G
What is VPR’s function?
down regulating response that limit viral infection
In what HIV type is VPU found?
HIV-1
In what HIV type is VPX found?
HIV-2
How is HIV transmitted?
sexual contact
What does HIV target?
Cells with CCR5 or CXCR5
CD4 T cells, macrophages, DCs, Langerhans cells
What viruses are preferentially transmitted by HIV?
viruses that use the CCR5 co-receptor
Is it possible to get an HIV infection without the co-receptor?
no.
When do anti-HIV antibodies appear?
3-8 weeks after infection
What does diagnosis of an acute HIV infection require?
Detection of the virus using RT-PCR
Are antibodies found during the window period?
No
If someone has a positive Rapid HIV antibody test, what is the next step?
ELISA/ Western blot
How can mother-infant transmission of HIV occur?
In utero, at birth, through breast feeding
Should HIV+ mothers breastfeed?
Nah
How is an infant diagnosed with HIV?
PCR for viral DNA
What are the stages of HIV infection?
Primary infection Clinical Latency Constitutional symptoms Opportunistic infection Death
What occurs during the HIV primary infection?
acute drop in T cell count
increase in HIV RNA copies
What occurs during the HIV Clinical latency period?
No symptoms, increase in T cells keeps HIV in check
What occurs during the HIV constitutional symptoms?
drop in T cell count, onset of AIDS.
Opportunistic infection can occur
What is the CD4 count in Stage I?
500 cells/mL
What is the CD4 count in Stage II?
200-499 cells/mL
What is the CD4 count in Stage III?
What is an early stage predictor of HIV?
viral load
What is a most important late stage predictor of HIV?
CD4 T cell count
What are elite controllers?
below 50 copies/mL
no progression/pathogenesis observed for a LONG time
What are long term non-progressors?
Have a very low viral load
Will have a longer latency period
What are progressors?
have a high viral load
much shorter latency period, quickly progress to AIDS
What is an AIDS defining illness?
A condition that, if present, means the patient has AIDS, no matter what their CD4 count is
What also HIV to escape the immune response?
antigenic drift and glycosylation of gp120
What is the purpose of anti-retroviral therapy?
To decrease the viral load and maintain the CD4 T cell count