Question

People who lack a particular protein on the surface of their cells are almost never infected with HIV despite multiple sexual contacts with an infected partner. That missing protein is _______

Answer 1

The missing protein on the surface of cells that prevents HIV infection is called CCR5. People who lack this protein, specifically those with the CCR5-delta 32 mutation, are almost never infected with HIV. The CCR5 protein acts as a co-receptor on the surface of T cells, which are the primary target cells for HIV. The mutation prevents the virus from effectively binding to the receptor and thus blocks viral entry into the host cell.

Step-by-step explanation:

The missing protein on the surface of cells that prevents HIV infection is called CCR5. People who lack this protein, specifically those with the CCR5-delta 32 mutation, are almost never infected with HIV despite multiple sexual contacts with an infected partner. The CCR5 protein acts as a co-receptor on the surface of T cells, which are the primary target cells for HIV. The virus needs to bind to this protein in order to enter and infect the cells.

By lacking the CCR5 protein, individuals with the mutation have greatly reduced susceptibility to HIV infection. Those who are heterozygous for the mutation have some protection from infection as well. The mutation prevents the virus from effectively binding to the receptor and thus blocks viral entry into the host cell.