Bloodborne viruses Flashcards
Whats the morphology/genome of HIV like?
Envelopped with linear, dimeric, ssRNA(+) genome
How many species of HIV are there?
2 - HIV-1 and HIV-2
How many groups are there in HIV-1
4: M, N, O, and P
Which strain of HIV is the one responsible for the global epidemic?
HIV-1 strain M
What is the dominant HIV-1 subtype in the americas?
HIV-1, group M, subtype B
Where is the greatest diversity and prevalence of HIV found?
Africa
How many out of 100 sexually active adults are infected with HIV worldwide
1/100
What are the 3 ways in which HIV can get transmitted? When is each more common?
- Sexually is most common (90%)
- IV drug use is also a method (%8)
- Vertical transmission in developing countries (25%)
What are the 3 stages in the progression of HIV?
- Primary infection
- Clinical latency
- AIDS
How long does the primary infection with HIV last?
3-6 weeks
What are the symptoms of the acute phase of HIV?
Mono-like symptoms: fever, maculopapular rash, oral ulcers, lymphadenopathy, malaise, weight loss, arthralgia, night sweats
What is the general patten of CD4 cell and antibody against HIV virus as the disease progresses?
both decrease as the viral load increases
- ultimately end at the wasting stage before death
What are kinds of opportunistic infections that can occur with HIV? Why?
Occur because the CD4 count drops
TB, HZV, pneumocystis, candida infections…
When is risk of sexual transmission highest?
during acute and late stage infection (higher viral loads)
What can be given to someone who may have been exposed to HIV?
post exposure prophylaxis (PEP)
How soon does PEP need to be given?
within 72 hours to be effective
-within 2 hours is best
What is the name for the kind of ARV therapy currently in use for HIV?
Highly active antiretroviral therapy (HAART)
What are the 4 general types of lab tests used for HIV
- HIV screening assays
- Confirmatory testing
- Viral loads to monitor treatment
- Antiviral resistance testing
What needs to be done if you get a positive result for an HIV screening assay? a negative result?
EIA positive: requires confirmatory testing
EIA negative: repeat over time (window period)
Why are the 4th gen EIAs for HIV so much better?
because they detect both HIV antigen and antibodies made against it
What is the window period?
the time between infection and when it can be detected in the lab
What is the window period for HIV using the 4th generation EIA?
2 weeks
What is seroconversion?
generation of antibodies against a particular pathogen/virus
Why do you need to perform multiple tests over time for HIV ?
because by 2-3 weeks, only 50% of people have seroconverted
What test is used as a confirmatory method for HIV? How does it work?
Western blot
HIV viral proteins separated by electrophoresis and transferred to nitrocellulose membrane
Will detect anti-HIV antibodies in serum
What is the HIV-1/HIV-2 immunoblot? what are the advantages?
Small card that you put blood and buffer on to.
Advantages: rapid, specific, and will detect both HIV-1 and HIV-2
When are 5 instances where you would use molecule methods for HIV detection?
- Monitor therapy (quantitative - viral loads)
- Earlier diagnosis during window period? - EIA over time…
- Supplemental test for problematic Western or immunoblot results (ex: persistent indeterminate)
- Testing of babies born to HIV-positive mothers
- Maternal antibody in babies persist up to 24 months - Late in disease (wasting) - seroreversion
What kind of test specifically is used to monitor viral load/ARV therapy?
quantitative RT-PCR
The most common HIV drugs are __ because they benefit from the presence of ___
Nucleoside and non-nucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs)
- because HIV has a viral RT
What are the 5 drug targets of HIV ARVs?
- Fusion inhibitors
- CCR5 co-receptor antagonists
- NRTIs and NNRTIs
- Integrase inhibitors
- Protease inhibitors
How does HIV resistance arise/why is it so common?
Because the RT lacks proofreading ability and so much viral replication is going on, you can get millions of variants per day
What is HIV resistance testing? How does it work?
test serum or plasma and do a RT PCR and amplify the sequence – then look for mutations in the sequences that are targets for the ARVs
What kind of genome/morphology is Hepatitis C virus? many types of genotypes or just one?
ssRNA (+), envelopped
multiple genotypes
approx. how many HCV carriers are there worldwide?
about 170 million
What are 6 symptoms of an infection with HCV?
- Abdominal pain
- Jaundice
- Nausea/vomiting
- Swollen abdomen
- itchy skin
- weight loss
What % of people develop a chronic HCV infection after the acute stage? what % of those patients will develop cirrhosis of the liver? what % of THOSE peeps will get ESLD and die?
60-85%
5%
25% will die
Why is the main method for testing HCV serology and not molecular methods?
Because the viral RNA load stays relatively constant over time
EIAs and confirmatory assays are used instead
What marker is used to monitor liver damage?
Alanine aminotransferase (ALT) = marker for liver damage
What is the flow of testing for HCV?
- EIA
- if negative test over time - NAAT test if EIA positive
- if positive = HCV pos - if NAAT negative -> do RIBA
- RT-PCR or recombinant immunoblot (RIBA) - If RIBA positive = HCV positive
- if negative then you repeat HCV EIA in a month
How does RIBA work?
confirms EIA through serology by testing anti HCV in serum
What is the point of doing HCV genotyping? How is it done?
will help determine treatment and duration
done doing a line probe assay
What are 3 types of direct acting antivirals (DAA) used in the treatment of HCV?
- RNA replicase inhibitors
- Protease inhibitors
- NS5A inhibitors
What kind of genome/morphology does Hep B have? Does it have a RT?
Enveloped, partially dsDNA
Yes has a viral RT
How many carriers of HBV are there worldwide?
About 350 million
How is HBV transmitted?
Can be vertical or horizontal
- horizontal from sexual contact, blood transfusion, sharing needles etc.
What is the difference between people who become chronically infected from a vertical vs. horizontal transmission?
90% of infants will become chronically infected where only 6% of people over the age of 5 become chronically infected
Who is more likely to enter the chronic stage of HBV infection?
children (90%) vs only 5% of adults
What % of children with chronic HBV infections go on to develop cirrhosis?
about 30%
- some of which will go on to develop ESLD
How can you prevent HBV?
Vaccination
What are 2 current treatments available for HBV?
alpha-interferon, lamivudine
- some other newer treatments as well
Vaccines against HBV are based on what antigens?
surface antigens
antibodies made against the core HBV viral protein tells you someone has been..?
infected and then become immune
Describe the difference between the acute and chronic graphs of HBV
for acute (that resolves): titre of surface antigen increases and then decreases, then Ab to the surface protein develops and tapers off. Ab to core antigen increases and remains constant
for chronic: while Ab to core antigen remains high, no Ab to surface protein develops and so the titre of surface protein remains high
