HIV - Virology and Clinical

Question 1

What activities allow HIV transmission?

Answer 1

• Anal or vaginal intercourse
• Injecting rugs and sharing equipment
• Mother-to-child transmission
• Transmission in healthcare settings
• Transmission via donated blood or blood clotting disorders

Question 2

Describe the HIV virus and how it affects cells

Answer 2

• Spherical, 60 times smaller then an RBC and contains two strands to RNA and three of it’s own enzymes (reverse transcriptase, integrase and protease)
• Finds CD4 receptors and is internalised, releases its RNA strands and uses reverse transcriptase to change RNA to DNA in cytoplasm, DNA moves to nucleus helped by integrase, integrated into hosts DNA, mRNA produced and then released back to cytoplasm, usus protease to produce more viral proteins and replicate

Question 3

What are the viral targets of HIV treatment?

Answer 3

• Fusion inhibitors
• R5 inhibitors
• Protease inhibitors
• NRTIs
• NNRTIs
• Integrase inhibitors

Question 4

What are the symptoms of acute HIV infection?

Answer 4

• Fever, weight loss, malaise, headache, neuropathy, sores, thrush, lymphadenopathy, nausea, vomiting, rash, spleen and liver enlargement, and myalgia

Question 5

How is HIV monitored?

Answer 5

• CD4 cell count (T-helper lymphocyte count, 600-1200/mm3 is negative, risk of infection increases greatly below 200/mm3)
• HIV-1 plasma RNA (viral load test, below 10,000 low and above 100,000 high, undetectable means below 40 copies/ml)

Question 6

How is HIV diagnosed?

Answer 6

• Antibody blood test
• PCR testing for p24 antigen
• PCR testing for HIV RNA tests for the quantity and gives the viral load

Question 7

Treatment of HIV

Answer 7

• Combination of antiretroviral therapy (ART) - offered to everyone irrespective of viral load or CD4 count
• Current guidelines suggest 2 NRTIs (i.e. tenofovir and emtricitabine) plus a third agen
• Highly Active Anti-Retrovirus Therapy (HAART) classes
  
  • Protease Inhibitors (PIs)
  • Integrase Inhibitors (IIs)
  • Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
  • Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTs)
  • Entry Inhibitors (EIs)
• Prophylactic co-trimoxazole (septrin) given to those with CD4 <200 to protect against PCP
• Monitor and reduce CR risk factors due to increased CV risk
• Yearly cervical smears due to increased risk
• Vaccinations for influenza, pneumococcal, hepatitis A and B, diptheria, polio - avoid live vaccines

Question 8

Post-exposure prophylaxis (PEP)

Answer 8

• PEP can be used to reduce risk of transmission after exposure
• Must be given within 72 hours - sooner the better
• Not 100% effective
• Involves combination of ART - currently Truvada (emtricitabine/tenofocir) and raltegravir for 28 days
• HIV testing should be done initially and a minimum of 3 months after exposure to confirm negative status