2/2/99

Microbiology II

 

·        HIV attack CD4 cells (T helper cells) which participate in many immune mechanism

·        CD4 cells fxn to induce mature B cells, natural killer cells, monocytes, suppressor T cells, macrophages and killer T cells

·        Know HIV life cycle on handout as well as the graph below life cycle

·        Initial CD4 coutn 1000 in week 0

·        CD4 count is 1/2 to 500 at week 5--# of virus copies highest before death

·        Slight increase may occur in CD4 count to 650 in week 12--# of virus copies lowest

·        # of CD4 cells = # of virus copies in yr 4-5

·        opportunistic diseases kick in at 10 years to death

·        Immune system damaged due to HIV so secondary infection result (opportunistic)

·        Asymptom stage = clinical latency

·        Pneumocystis karinii = major cause

·        #1 killer as secondary infection mycobacterium is killer too

 

Symptoms

·        unexplainable weight loss of 10%

·        prolonged fever >1 month

·        diarrhea

·        Kaposi's sarcoma--skin cancer

·        Repeated respiratory infections--inability to fight back

 

Dx

·        Look at clinical features

·        Do serodiagnostic tests--ELISA, Western Blot, PCR

·        ELISA tests for Ab's in serum, might take months after exposure to HIV to become (+)

·        Has false negativity (1/50,000)

·        Western Blot tests for viral proteins--must be at least 1 month after exposure to be (+)

·        False negativity 1/500,000

·        PCR = polymerase chain reaction--test for viral nucleic acid

·        Used for magnifying a single copy of nucleic acid into multiple copies of same nucleic acid

·        Detectable w/in 2-4 days after exposure

·        False negativity in 1/2.5 million

 

Table 4-1-- anti-HIV therapy

            AZT, DDI, saquinavir--combination of these 3 drugs used today

            AZT and DDI-- inhibit virus production

            Saquinavir--protease inhibitor