W06_03 Pathogenesis of HIV and AIDS Flashcards
how did HIV affect T cells?
causing the T cells to fuse, and then die
what’s the typical course of HIV infection?
ADD THE SLIDE!
get infected, HIV titre goes up, T cells come down, but then around 6 weeks, our bodies can fight the infection. T cells recover, but slowly fall, at about 50 cells/mm3 per year. below a count of 200, you start to get really bad symptoms - AIDS.
what’s the definition of AIDS?
acquired immunodeficiency syndrome.
1) presence of HIV infection and
2) presence of opportunistic infection or a T cell count of <200 cells/mm3
how does an HIV virion bind to a cell?
gp120 on virion binds to CD4 and co-receptor on T cell
what aspect of the virus life cycle makes the HIV infection difficult to eradicate?
virus integrates into the DNA of the cell, so you have to kill all the T cells
what are the two types of known co-receptors for HIV’s gp120?
CXCR4 and CCR5
what’s the natural ligand for CXCR4?
SDF-1
what’s the natural ligand for CCR5?
MIP-1alpha, beta; RANTES
which mutation gives individuals resistance to certain strains of HIV-1?
CCR5
should you give immunization vaccines to HIV patients?
no, it’ll hyperactivate the HIV. things like TNFa, IL-1, IL-6 make HIV crazy
how does TNFa increase HIV?
increases NF-kB activation, which goes to bind LTR of HIV-1 and enhances HIV transcription
HIV makes 1 billion virions a day!
okay
note: there is a direct-killing hypothesis and an indirect-killing hypothesis in HIV/AIDS
CD4 cells not infected with AIDS will also die ex vivo…belief is that HIV releases antigens that activate CD4 cells and force apoptosis
what happens in the gut in early HIV infection?
peyer’s patches gone. so lack of immune system there predisposes the bacteria to survive, and even translocate into the blood. high LPS in blood = high T cell activation = early apoptosis
note CD4 T cells don’t respond to their normal cytokine stimuli
like IL-2 - fail to proliferate in response to this
how is HIV diagnosed?
direct virus directly;
see if antibody response is mounted against HIV antigen - ELISA + western blot
which bands do labs look for when western blotting for HIV?
gp120, gp160, gp41
what’s the next generation HIV test that we use in Ontario?
HIV-1/HIV-2 antibody AND
gp24 antigen test in ELISA
how long does it take to be able to detect these HIV antigens by ELISA and western blot?
4-6 weeks
note: the amount of HIV titre in the blood directly influences how quickly the CD4 cells will decrease, and how quickly the person will die
okay
why does HIV increase susceptibility to TB?
recall that CD4 cells are there to help the macrophage digest the intracellular TB
