S8) Blood Borne Viruses – HIV Flashcards
What are some key signs of HIV?
- Oral candidiasis
- Kaposi’s sarcoma
- PCP (Pneumocystis pneumonia)
In terms of infection model, outline the possible outcomes for a patient with HIV
Describe HIV acquisition by risk group
Which parts of England have had the biggest increases in HIV transmission in the last 10 years?
- East of England
- North East
- Midlands
Identify and describe the 4 key features in viral structure and behaviour
- Genome – RNA or DNA (ss/ds)
- Capsid – protein shell, protects the genome (helical/icosahedral)
- Lipid envelope – derived from host cell membranes (present/absent)
- Replication strategy
What is the Human Immunodeficiency Virus?
- HIV is a retrovirus which infects cells with CD4+ surface receptor (T-helper cells, monocytes / macrophages)
- It replicates inside cells, destroys the cell, causes inflammation and spreads to / infects more cells
How is HIV transmitted?
Transmission through contact of infected bodily fluids with mucosal tissue / blood / broken skin
What are the 5 different ways in which HIV can be transmitted?
- Sexual contact
- Transfusion
- Contaminated needles
- Medical procedures (organ donation, skin grafts, blood products)
- Perinatal transmission (transplacental, during delivery, through ingestion of breast milk)
Outline the 7 steps involved in retroviral replication
⇒ Virus binds to a CD4+ on cell surface & fuses with cell
⇒ Virus penetrates & empties contents into cell (infection)
⇒ Viral ssRNA → dsDNA by reverse transcriptase
⇒ Viral DNA is integrated into host’s DNA by integrase
⇒ Viral DNA is transcripted during infected cell division
⇒ Viral protein chains assemble & bud out of cell (immature – breaks free)
⇒ Virus matures as protein chains are cut by protease
Outline the 4 different phases of an HIV infection in terms of CD4+ count and viral load
Identify the different stages of HIV, in terms of the symptoms and CD4 count
What are the main symptoms of Acute HIV infection, with regards to the following areas:
- Systemic
- Lymph nodes
- Skin
- Gastric
- Muscle
- Mouth
- Lymph nodes – lymphadenopathy
- Skin – rash
- Muscles – myalgia
- Systemic – fever, weight loss
- Gastric – nausea, vomiting
- Mouth – sores, thrush
What are the factors affecting HIV transmission?
- Type of exposure – type of sexual act, transfusion / needlestick / mucous membrane
- Viral level in blood
- Condom use
- Breaks in skin/mucosa – other STI / sexual assault
What are 4 factors which enable people with HIV to live healthy lives?
- Early detection
- Treatment
- Adherence
- Healthy living
Outline Serology as a diagnostic test for HIV
- Detects HIV antigen (Ag) and HIV antibody (Ab)
- Result on same day
- May get false negative result (if performed too early –wait 4 weeks)
Outline PCR as a diagnostic test for HIV
- Detects HIV nucleic acid
- Highly sensitive (detects very early infection)
- Expensive
- Slow results (up to 1 week)
- Used for follow-up / treatment response
Outline Rapid tests as a diagnostic test for HIV
- Detects HIV antibody
- Blood test (finger-prick) / oral (saliva)
- May get false positive result (confirm with serology)
Who should be tested for HIV?
Everyone
What are the aims of HIV treatment?
- Undetectable HIV viral load
- Reconstitute CD4 count
- Reduce general inflammation
- Reduce risk of transmission
- Normalise lifespan & QoL
Which 2 medicinal strategies would you use to treat and reduce the prevalence of HIV?
- Anti-retrovirals (ARVs)
- Vaccination
When should one start HIV treatment?
Compare and contrast previous and current guidance
- Previous guidance – CD4 < 350, primary HIV infection, any AIDS-defining illness, cancer/lymphoma, prevent transmission to others, patient choice
- Current guidance – treat everyone ASAP, regardless of CD4 (significant benefits in AIDS & non-AIDS morbidity and mortality)
Which ARVs can be used?
Nucleoside reverse transcriptase inhibitor (2x)
+ Non-nucleoside reverse transcriptase inhibitor
OR + Protease inhibitor
OR + Integrase inhibitor & CCR5 (entry) inhibitor
Why give 3 ARVs?
- Virus mutates & replicates largely
- Resistance to drugs develops in days
- Harder to develop resistance to 3 drugs
Which 5 non-medicinal strategies would you use to treat and reduce the prevalence of HIV?
- Increase condom usage
- Prevent vertical transmission
- Medical circumcision
- Post-exposure prophylaxis (PEP)
- Pre-exposure prophylaxis (PrEP)
Identify and describe some aids-defining illnesses
- TB – coughing, fatigue, weight loss
- PCP – high fever, cough, difficulty breathing
- Cryptococcal disease – pneumonia, brain swelling, skin infections and UTI
- CMV – difficulty with vision, pneumonia and gastroenteritis
- Cryptosporidiosis – severe diarrhoea, abdominal cramps
