BBV Flashcards
Discuss the features of Hepatitis B
- Heoadnavirus -DNA
- Immune reaction to the presence of the virus - infects hepatocytes
- 6 genotypes A-F -High prevalence in SE Asia. subsaharan africa ect
Features: 6 week incubation period- 6months
- Non-specific fever and malaise prodrome -50% infections asymptomatic
- Chronic infection- cirrhosis , hepatocellular carcinoma
- Antigen of Hep B= BHsAG - grossly overproduced so there is free antigen in the blood
- HBeAg - another viral component
Describe the tolerogen effect of Hep B
- E antigen is soluble and has a tolerogen effect (decreases the immune system)
- Can cross the placenta and allows foetus immune system to recognise it as self antigen- causes clonal detection of lymphocytes recognising the E antigen
- Leads to chronic infection- no immune response so virus won’t clear
Risk of chronic infection relates to age of infection - younger age= more likely
Describe the features of perinatal transmission of Hep B
- E-antigen predicts the likelihood of transmission
- Mother positive for HBsAG and HBeAG then 70-90% chance of infection
- Positive for just HBsAG then less than 10%
What do these markers for Hepatitis b indicate
HBsAG HB core antibody (IgG) BH core antibody (IgM) e antigen Anti-HbsAg HBV DNA
HBsAg= current infection
HB core antibody IgG= past/ present infection (will still have this even if completely cured)
Hb core antibody IgM= Acute/ recent infection
E antigen= Highly infective, high grade infection
-Anti-HBsAg- Immunity (natural or vaccine)
-HBV DNA= measures response to treatment
What are the 2 types of HBV chronic infection
- E-antigen positvie- high grade infection with increased risk of transmission- chronic acute hepatitis, cirrhosis and hepatocellular carcinoma likely
- E-antigen negative - Low grade infection, low risk of onward transmission, nit likely to have clinical effects
Discuss the vaccine and treatment options for HBV
- -Vaccine= genetically modified recombinant vaccine
- Target is neonates born to HBV positive mum, healthcare workers, dialysis patients, young gay men and contacts of cases
Treatment options for HBV
- Lamivudie- suppressions so decreases amount of virus so that it can’t cause disease
- Interferon- switch off high grade infection- long term recovery
- Transplant
What theronostic tests are available for HBV
- Theronostic means to check if medication is working properly
1. Lamivudine resistance- sequence the virus gene- usually will become resistant within 2 yrs
2. HBV DNA- assess response to Lamivudine
Discuss the features of hepatitis C
- Blood transmission= main route
- Infects hepatocytes (direct viral effects and immune mediated inflammation)
- 6 genotypes - type 1= poor prognosis and type 3 is good prognosis
- Asymptomatic in acute stage
- 70% develop acute infection
- 20% develop cirrhosis
What are the various markers used in Hepatitis C
- HCV antibody- past/ present infection
- HCV RNA (by PCR)- Current infection
- HCV genotype- guide for treatment type 1= 1-12 months and type 3= 6months
Current infection= Antibody + positive PCR
Past infection= Antibody positive and negative PCR
What are the treatment options for Hepatitis C
- Interferon and ribavirin- treat high grade infection
- Transplant- HCV recurs in 100% of grafts
Theronostic assays-
- Genotype decides treatment duration
- HCV RNA on PCR determines treatment response
Describe the features of HIV
- Retrovirus -Common in subsaharan Africa
- Infects immune cells CD4 lymphocytes (Th cells) and macrophages
- Immunosuppression due to reduced T cell function
- 2 main subtypes HIV 1 (most common) and HIV 2
2 diseases
- Primary HIV infection 10-25 days after exposure- glandular fever like illness , lymphadenopathy, rash, fever
- AIDS- 8 yr post exposure, opportunistic infections, weight loss
What are some of the opportunistic infections involved in AIDS
Viral
Bacterial
Protozoa
Fungi
Viral= CMV (retinitis), EBV (CNS, lymphoma) , JC polymavirus (encephalopathy)
Bacterial= Typical/ atypical mycobacteria- TB (major killer)
Protozoa= Toxoplasma (CNS infection), Cryptospoidia (bloody diarrhoea- life threatening)
Fungi= Candida (oesophageal) Pneumocytis (pneumonia), cryptococcus (meningitis)
How is HIV diagnosed and treated
- HIV antibody = infection
- 4 assays used to rule out any false positives
Treatment
- Antiretroviral therapy- suppression
- Combination therapy- 3 antiretroviral drugs from at least 2 classes
Classes of drugs
- Nucleoside reverse transcriptase inhibitors
- Non-nucleoside reverse transcriptase inhibitors
- Protease inhibitors
How do you prevent mother to baby transmission of HIV
- C-section birth
- ART to mother and baby
- No breastfeeding
What theronostic assays are used in HIV
- Viral load- viral RNA in blood
- CD4 t lymphocyte count- determines response to treatment
- Mutational analysis for drug resistance
