patho 2 HIV & AIDS

GP120 and GP41

allow for HIV to gain entry into the cell

1st step of viral replication

HIV binds to CD4 cell. RNA, proteins, and enzymes released

2nd step of viral replication

HIV reverse transcriptase converts viral RNA into DNA

3rd step of viral replication

HIV DNA moves to nucleus and spliced into host’s DNA

4th step of viral replication

HIV RNA moves out of the nucleus into cytoplasm and makes long chains of viral proteins and enzymes

5th step of viral replication

immature viral particle forms containing cellular and HIV proteins. chains cut into smaller pieces by protease

6th step of viral replication

infectious viral particle ready to be released containing HIV RNA, viral proteins and enzymes

helper T cells (CD4 cells)

coordnite and activate both B lymphocytes (antibody mediated) and cell-killing cytotoxic (CD8) lymphocytes (cell mediated)
cell-mediated immune response → copes with microbes located within cells
HIV infects and destroy these
loss of these cells → immune system collapse and HIV disease

cytotoxic T-cells (CD8 cells)

important in initial immune response to HIV and at latent stage
kill infected cells that are producing virus
secrete soluble factors that suppress HIV replication-these factors block by occupying receptors necessary for the entry of certain strains of HIV into the target cell

ELISA testing

enzyme linked ImmunoSorbent assay determines response of antibodies to HIV virus

western blot

confirms presence of HIV antibodies
usefull in children older than 18 months of age
positive HIV antibody test in children younger than 18 months of age indicates only that mother is infected

p24 antigen

only a positive result is significant
two or more positive results are diagnostic for HIV infection
used to detect HIV antigen in childrne younger than 18 months
useful at any age

CD4+ test

used to assess immune status, risk for disease progression, and need for PCP prophylaxisD

DNA HIV test

viral nucleic acid test
polymerase chain reaction (PCR)
nucleid acid sequence based amplification
branched chain DNA tests

viral culture test

highly specific but negative result meaningless
not frequently used to diagnose HIV

immunofluorescence antibody testing

alternative to western blot for comfirnatiion of HIV infeciton

persistent generalized lymphadenopathy

lymph node enlargement 1 cm or greater in two or more extra-inguinal sites
adenopathy persists longer than 3 months

genotypic assay

detect drug resistance mutations present in relevant viral genes

phenotypic assays

measure the ability of a virus to grow in different concentrations of antiretroviral drugs

highly active antiretroviral treatment (HAART)

keep viral load to undetectable levels and minimize seeding of the lymphatic system with HIV
multi-drug approach thought to strike at various points of the viral life cycle

reverse transcriptace inhibitors

act early in the life cycle of the HIV
prevent HIV enzyme from creating HIV proviral DNA from viral RNA → prevents new viruses from being produced

protease inhibitors

act late in the life cycle of the HIV
block HIV enzyme protease → prevent creation or cleavage of HIV polyproteins necessary for production of new virons

fusion inhibitor

attach to proteins on surface of T-cells or HIV
prevent binding of proteins on HIV’s outer coast (GP120, GP41) with surface receptors on T-cells