Bloodborne viruses Flashcards
What morphological characteristic do all bloodborne viruses have in common?
They are all enveloped
What is HIV and what strain is responsible for the global HIV epidemic?
HIV is an enveloped virus with a linear, dimeric ssRNA genome of the retroviridae family. Group M viruses are responsible for the epidemic
What are the 3 ways HIV is transmitted?
Sexually (90%)
Intravenous drug use (8%)
Vertically in developing countries (25%)
Describe the progression of HIV infection
1) Primary infection: 3-6 weeks, mononucleosis like symptoms: fever, morbilliform rash etc.
2) Clinical latency: years
3) Acquired immunodeficiency syndrome: opportunistic infections and/or tumors
At what stages of HIV infection are risk of sexual infection the highest? Why?
During acute and late stages because viral loads at these points is the highest
What is the HIV screening assay used today? Why is it used over older HIV screening assays?
A 4th generation EIA. 4th generation assays are better than older generations because they can detect HIV antigens and all anti-HIV antibody classes. 4th generation EIA also have the shortest window period (period between infection and laboratory detection) (2 weeks)
What is seroconversion?
Seroconversion is period of time it takes for an individual to make antibodies against HIV antigens and for them to become detectable in blood. Usually takes 12 weeks for serology to become 99% positive for HIV antibodies
When is HIV-1 western blotting used?
Used to confirm a positive EIA test and to detect anti-HIV antibodies in serum
What are 5 circumstances where molecular methods would be used for HIV infection?
1) Monitoring therapy such as viral loads
2) Earlier diagnosis during window period over EIA
3) Supplemental testing (problematic Western blot or immunoblot results)
4) Testing babies born to HIV positive mothers
5) Late in disease - seroreversion: low numbers of T cells, low/no anti HIV antibodies - serology not usefull
How does HIV drug resistance arise?
Reverse transcriptase lacks proof-reading ability which results in many mutations when RNA is RT to DNA and incorporated into the host genome
Describe the morphology of Hepatitis C virus
HCV is an enveloped ssRNA virus of the flaviviridae family. There are different genotypes of HCV
What are some HCV transmission risk factors and symptoms?
Risks: IV or snorted drug use, tattoos, vertical transmission, higher risk sex
Symptoms: abdominal pain, jaundice, nausea/vomiting, swollen abdomen, itchy skin, weight loss
Describe the progression of HCV disease that may occur
HCV exposure - acute infection - persistent/chronic infection - cirrhosis - End stage liver disease/hepatocellular carcinoma/death
Describe HCV diagnosis and supplemental testing done
HCV EIA screening - confirmation with RT-PCR or recombinant immunoblot - genotyping to guide therapy - monitoring of therapy through viral load determination with RT-PCR
What is HCV-RIBA?
Herpes C virus recombinant immunoblot assay - used to confirm a positive EIA using serology by looking for anti-HCV antibodies