HIV Flashcards
HIV types
HIV-1
- Most common in US and worldwide
HIV-2
- Very rare and less pathogenic
- AIDs more prevalent in Western Africa and Southern Asia
HIV pathophysiology
Targets CD4 T cells
- Attaches to CD4 vis gp120 protein on its envelop
Gp120 also attaches to co-receptor
- CXCR4
- CCR5
Reverse transcriptase
- Allow transcription of ssRNA into ds proviral DNA
Proviral DNA
- Inserts itself into cell’s DNA
- Allows the cell to transcribing new proteins for HIV virsuses
HIV resistance
People with homozygous mutation for co-receptors show HIV resistance
- HIV requires binding to CD4 as well as co-receptors in order to enter cells.
HIV virology
SS RNA retrovirus
R5 strain of HIV
Typically spread sexually
Binds to CCR5 co receptor
Infects
- Macrophages
- Dendritic cells
- T cells
Presentation of HIV
- Acute
- Chronic
Acute infection (first 12 weeks) - Flu like symptoms/ mononucleosis
Low viral load by week 12= chronic phase (2-10 years)
- Viral load slowly increases
- T cell count slowly decrease.
- <500mm3= symptoms
X4 strain of HIV
Appears more in chronic phase due to acquired mutation
- Binds to CXCR4
Present in lymphoid tissue and only targets T cells
AIDS
Later phase of HIV where T cell count is very low <200mm3
- Enough to severely compromise the immune system and cause life-threatening opportunistic infections/ cancers
Presentation
- Fever
- Fatigue
- Weight loss/ cachexia
- Diarrhoea
AIDS defining infections
Recurrent bacterial pneumonia
Pneumocystis pneumonia
Candidiasis
- Oesophageal
Tumours
- Kaposi sarcoma (most common)
- Primary CNS lymphoma
- Cervical cancer
- Burkitt’s lymphoma
HIV transmission
Sexual intercose= most common
- anal receptive shows highest rate
Vertical transmission
- Mother to child via childbirth/ placenta/ breastfeeding
Needle sharing
HIV investigations
Point of care test= Serum HIV rapid test
- Detects HIV ab in blood.
- can be detected 3-4 weeks post infection
Serum HIV ELISA
- Searches for present HIV antibodies
- If positive/ reactive= more specific test
specific tests
- PCR
- Western blot
- Nucleic acid testing
Positive ELISA + positive western blot/ PCR= HIV-positive
CD4 count
HIV co receptors
CCR5
CXCR4
HIV reverse transcriptase
Enzyme that allows the synthesis of a DNA copy of HIV’s RNA.
The enzyme is very error prone, which allows a high rate of HIV mutation.
Window period
The period of time required for the body to produce enough HIV ab to be detectable by HIV tests.
HIV treatment
Anti-retroviral drugs (ART)
Bictegravir/ tenofivir/ emtricitabine
