Flashcards in HIV Deck (70)
What is HIV?
HIV-2 originated in West African Sootey mangabey
HIV-1 originated in Central/West African chimpanzees: HIV1 group M responsible for global pandemic
What is the target site for HIV?
What cells are CD4+ receptors found on?
T helper lymphocytes
What do CD4+Th lymphocytes do?
Essential for induction of adaptive immune response
Recognition of MHC2 APC
Activation of B cells
Activation of cytotoxic CD8+ T cells
What effect does HIV infection have on immune response?
Sequestration of cells in lymphoid tissues
-Reduced circulating CD4+ cells
Reduced proliferation of CD4+ cells
Reduction CD8+ (cytotoxic) T cell activation
-Dysregulated expression of cytokines
-Increasing susceptibility to viral infections (including HIV)
Reduction in antibody class switching
-Reduced affinity of antibodies produced
Chronic Immune Activation (microbial translocation)
What does HIV increase susceptibility to?
At what CD4+Th count is there a risk of opportunistic infection?
Normal is 500-1600
Describe HIV viral replication
Rapid in very early and very late infection
New generation every 6-12hours
How does HIV spread in the body?
Infection of mucosal CD4 cell (Langerhans/dendritic)
Transport to RLNs
Infection established within 3 days of entry
Dissemination of virus
When is the usual onset of HIV?
2-4wks after infection
What are the common symptoms of primary HIV infection?
Up to 80% present with symptoms
What happens during the asymptomatic HIV infection?
Ongoing CD4 count depletion
Ongoing immune activation
Risk of onward transmission if remains undiagnosed
What is an opportunistic infection?
An infection caused by a pathogen that does not normally produce disease in a healthy individual. It uses the “opportunity” afforded by a weakened immune system to cause disease
What organism causes pneumocystis pneumonia?
What are the symptoms and signs of pneumocystis pneumonia?
How is pneumocystis pneumonia diagnosed?
CXR: May be normal, interstitial infiltrates, reticulonodular markings
BAL and immunofluorescence +- PCR
What is the treatment and prophylaxis for pneumocystis pneumonia?
Rx- High dose co-trimoxazole (+- steroid)
Proph: Low dose co-trimoxazole
What tuberculosis infections/conditions are more common in HIV+ than HIV- individuals?
Symptomatic primary infection
Reactivation of latent TB
Multi-drug resistant TB
Immune reconstitution syndrome
What organism causes cerebral toxoplasmosis?
What happens in cerebral toxoplasmosis?
Reactivation of latent infection
Multiple cerebral abscess (chorioretinitis)
What are the symptoms/signs in cerebral toxoplasmosis?
Raised intracranial pressure
What does CMV cause?
Retinitis, colitis, oesophagitis
How does CMV present?
Reduced visual acuity
What skin infections can be due to HIV?
Herpes Zoster: Multidermatomal, Recurrent
Herpes Simplex: Extensive, Hypertrophic, Aciclovir resistant
Human papilloma virus: Extensive, Recalcitrant, Dysplastic
What causes HIV-associated neurocognitive impairment?
How does HIV-associated neurocognitive impairment present?
+- motor dysfunction
What causes progressive multifocal leukoencephalopathy?
Reactivation of latent infection
How does progressive multifocal leukoencephalopathy present?
What are some other neurological presentations of HIV?
Distal sensory polyneuropathy
Viral meningitis (CMV, HSV)