Blood Borne Viruses- HIV Flashcards
Identify 3 main conditions associated with HIV
(Name 2 associated with lungs)
How can the virus affect latent infections
Oral candidiasis
Kaposi’s sarcoma
Pneumocystis pneumonia, TB
Latent infections can be reactivated
In the UK, which 4 areas have highest rates of HIV
Who should be treated and when
London, East England, North East, Midlands
Everyone, ASAP
Identify 4 main features of a virus
- Genome- RNA/ DNA (ss or ds)
- Capsid- Protein shell, protects genome
- Lipid envelope- Present/ absent, contains antigens
- Replication strategy
What is HIV?
A retrovirus that interacts with CD4 surface receptors
Retrovirus= ssRNA->DNA->ssRNA
Describe the 8 steps in Viral Replication
- Binding and Fusion: Virus binds to CD4 receptor and fuses with cell
- Infection: Virus penetrates cell, emptying contents in
- Reverse Transcription: ssRNA-> dsDNA by Reverse Transcriptase
- Integration: Viral DNA combined with cell’s by Integrase
- Transcription: During cell division, viral DNA read and protein chains made
- Assembly: Protein chains come together
- Budding: Immature virus pushes out of cell
- Maturation: Protein chains cut by Protease-> Individual proteins
How is HIV transmitted
Give 4 examples
Contact of infected bodily fluid with mucosal tissue/ blood/ broken skin
- Sexual contact
- Contaminated needles
- Perinatal transmission (During delivery/ Breast milk ingestion)
- Medical procedures (Transfusion/ Skin grafts/ Organ donation)
Name the 4 stages of HIV infection
Describe the 1st stage, including its time period, Viral load, and CD4 count
At which stage do symptoms start to show?
- Primary infection: Few months
- Rapid increase in Viral load-> decrease to ‘set point’
- Small decrease in CD4 count-> partial increase - Latent infection
- Symptomatic infection (Symptoms show)
- Severe infection/ AIDS
Describe the 2nd stage of HIV Infection
Include Viral load, and CD4 count
Latent Infection
- Gradual increase in Viral Load
- Gradual decrease in CD4 count
Describe the 3rd stage of HIV Infection
Include Viral load, and CD4 count
Symptomatic infection
- Slow increase in viral load
- Slow decrease in CD4 count to below 350 cells/ microlitre
Describe the last stage of HIV Infection
Include Viral load, and CD4 count
Severe infection/ AIDS
- Gradual increase in viral load
- Decrease in CD4 count to below 200 cells/ microlitre
What are the main symptoms of Acute HIV, in regards to;
- Systemic
- Mouth
- Muscles
- Skin
- Gastric
- Systemic- Fever, weight loss
- Mouth- Sores, thrush
- Muscles- Myalgia
- Skin- Rash
- Gastric- Vomiting, Nausea
What are 4 factors that affect HIV transmission
- Type of exposure (Type of sex/ transfusion/ needlestick)
- Viral load in blood (Transmission unlikely if undetectable VL)
- Condom use
- Breaks in skin/ mucosa (Other STI/ Sexual assault)
What is the average lifespan of HIV patients?
What are 4 factors that allow a long lifespan?
78 years
- Early detection
- Treatment
- Adherence (To treatment)
- Healthy living (Smoking, drinking)
Name 3 kinds of Diagnostic Tests used to detect HIV
Serology
PCR
Rapid tests
What does a HIV Serology test detect
When do you get the result?
What incorrect result may be obtained?
Detects HIV antigen and antibody (Part of immune response)
Result on same day
May get a False Negative
What does a HIV PCR test detect
Why is it not used for initial HIV testing?
What is one good thing about this test?
- Detects HIV Nucleic Acid
- Expensive, Slow so used for follow-ups
- Detects early infection (Few days)
What does a ‘Rapid’ HIV test detect
What are the 2 mechanisms
How accurate are negative and positive results?
How can we confirm?
- Detects HIV Antibody
- Blood test (Finger prick)
- Oral (Saliva)
- Negative results are accurate
- May get a false positive (Confirm with serology)
Name 2 strategies to reduce HIV Prevalence
- Vaccination
- ARVs (Anti-retroviral drugs)
Which 4 stages of Viral Replication are targeted by ARVs
- Binding and fusion
- Reverse Transcription
- Integration
- Maturation
Which kinds of ARVs drugs are used to treat HIV
2 Nucleoside Reverse Transcriptase Inhibitors \+ 1 Non-nucleoside Reverse Transcriptase Inhibitor OR 1 Protease Inhibitor OR 1 Integrase Inhibitor OR 1 CCR5 (Entry) Inhibitor
Why give 3 ARVs?
The virus mutates every 2-3 rounds of replication (Millions of rounds each day)
Thus, 3 drugs vs 1 drug= Harder to develop resistance
What is risk of transmission of HIV from a needlestick injury
1 in 300 (Less if on treatment/ VL is undetectable)
State 3 features of the HIV structure
Single stranded
Enveloped
RNA
