HIV, Hep B, Hep C Flashcards
What are the peripheral signs of HIV/immunocompromised?
Oral candidiasis, kaposi’s sarcoma, PCP: Pneumocystis carinii pneumonia
Describe the principles of HIV structure
SsRNA, capsid, lipid envelope
Briefly outline HIV replication
Reteroviruses = ssRNA –> DNA –> ssRNA within CD4 cells = T-helper, macrophages = destroys cell = inflam = infects more cells
Outline the stages of HIV replication
1) binding and fusion by CD4 and coreceptors,
2) infection,
3) reverse transcription,
4) integration with host DNA by integrase,
5) transcription,
6) assembly of viral proteins,
7) budding of immature virus out of the cell,
8) immature virus breaks free of cell,
9) maturation: viral proteins cut by protease = working virus
What 3 key enzymes are involved in HIV replication within a host cell?
Reverse transcriptase, integrase, protease
How is HIV transmitted?
Contact with large quantities of body fluids = sexual, transfusion, needles, medical procedures, perinatal transmission
Outline the stages of the HIV viral load
Primary infection: very high viral load, Ab response, can present like glandular fever.
Latent: (months-years) low viral load (lower = healthier the pt) CD4 count drops with the rise in viral load.
Symptomatic infect: CD4 count <350, infections present.
Severe/AIDS: <200
What are the main symptoms of acute HIV?
Fever, weight loss, pharyngitis, myalgia, hepatosplenomegaly, nausea, vomiting, rash, lymphadenopathy
What factors affect HIV transmission?
Types of exposure, viral load, condom use, breaks in skin/mucosa, other infections meaning the barriers are weaker
Outline HIV testing
Serology: Ag and Ab, can pick up within 4 weeks.
PCR: detects HIV nucleic acids, expensive slower, not used for screening.
Rapid: Ab, finger-prick, <1hr
Who should be tested for HIV?
Everyone if rate >2/1000
Outline HIV treatment
To achieve and undetectable HIV load, reconstitute CD4 count, reduce inflam, reduce risk of transmission = 3 diff ARV anti-retroviral drugs to manage the level of mutations
Why isn’t there a vaccine for HIV?
Constant mutation of envelope proteins
What is an elite controller?
Able to manage HIV viral load more efficiently
Apply the infection model to a patient with HIV and acquired immunodeficiency syndrome (AIDS)
Pathogens: viral, fungal, protozoal of particular concern.
Outcome: chronic infect or death (probable if diagnosed late/untreated)
How is Hep B + C transmitted?
B: blood, sex, vertical. C: blood, sex
Hep B structure
DsDNA, enveloped
What are the symptoms of acute hep b?
Asymptomatic, jaundice, fatigue, abdominal pain, anorexia/nausea/vomiting
How does Hep B serology change over time?
Surface Ag first, e-Ag, core Ab (IgM), e-Ab, surface Ab, core Ab (IgG)
How do you know a chronic Hep B infection is present?
Test for surface Ag: +ve 6 months after = chronic
-ve surface Ab = not mounted good enough immune responce
What is the treatment for Hep B?
No cure, life-long anti-virals but not required for inactive carriers
Who is at risk of Hep C infection?
IV drug users, sexual contact, infants to HCV+ve mothers, blood transfusion prior to 1991
What is the main diff between Hep B and Hep C?
Hep C = ~80% become chronically infected if untreated = liver disease, hepatocellular carcinoma, transplant, death
Hep B = vaccine
Symptoms of Hep C?
80% asymptomatic, 20% vague symptoms
Hep C blood test?
Serology: Ab only, viral PCR
Hep C treatment?
CURE: anti-viral drug combo, 8-12 weeks, >90% cure
Which virus, Hep B or Hep C, has a vaccine?
Hep B
What is PEP?
Post exposure prophylaxis – x3 ARVs, HIV: up to 72 hours
When comparing HIV, Hep C, Hep B, what is the risk of transmission?
HIV 1/300, HC 1/30, HB 1/3
HIV: acute infect, prevention, outcome untreated, treatment
Flue like symp/nil, condoms PEP, AIDS, life-long ARV
Hep B: acute infect, prevention, outcome untreated, treatment
Jaundice/abdo pain/anorexia, vaccine, cure (majority) chronic minority, nil/life-long ARV
Hep C: acute infect, prevention, outcome untreated, treatment
Nil, avoidance, chronic infect (majority), 8-12 weeks ARV
Using serology how can a past (cleared) infect be identified?
-ve surface Ag
+ve core Ab
+ve surface Ab
Regarding serology how can you tell if someone has been vaccinated?
- ve surface Ag
- ve core Ab
+ve surface Ab
