HIV- lqc 9a Flashcards
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describe how HIV invades T helper cells
Glycoprotein molecules on the surface of HIV called gp120 bind to CD4 receptors on the surface of T helper cells. The HIV envelope fuses with the T helper cell surface membrane and the HIV capsid enters the cell. The capsid releases the RNA genome, reverse transcriptase and integrase into the cytoplasm.
why can HIV also infect macrophages
macrophages have CD4 receptors
describe what happens after HIV has entered the T helper cell
Reverse transcriptase manufactures DNA from the RNA genome by reverse transcription. The new DNA is integrated into the host cell’s genome using the enzyme integrase. The viral genome can now be transcribed and translated to produce new viral RNA and proteins.
how does HIV destroy T helper cells
Once the new viral RNA genome, enzymes and capsid proteins are made they are assembled into new virus particles. The gp120 is packaged by the Golgi into a vesicle and sent to the T helper cell membrane. As the new virus particle buds out of the cell some of the host cell membrane, with the gp120, envelops the particle. The host T helper cell dies. Infected T helper cells will also be destroyed by T killer cells.
what is the consequence on the immune system
As the number of virus particles increase the number of T helper cells decreases. Macrophages, B cells and T killer cells are unable to be activated successfully and the immune system becomes deficient.
