In the late 1990s, a group of individuals was discovered that remained uninfected with HIV, in spite of multiple exposures to the virus. Analysis indicated that these HIV-resistant individuals had a homozygous deficiency caused by a 32-bp deletion in a single gene, and furthermore, that this mutation was present at a frequency of ~10% (in heterozygous form) in individuals of European descent. These data provided clear evidence indicating that:
A) Healthy individuals can have a genetic deficiency in the expression of CD4.
B) Testing for HIV by seroconversion does not identify all infected individuals.
C) HIV infection requires a co-receptor in addition to CD4.
D) Some individuals can be infected with HIV but not develop AIDS.
E) Both R5 and X4 variants of HIV are equally important in HIV transmission.

Question

Quizplus · Accepted Answer

The discovery that individuals with a homozygous deficiency caused by a 32-bp deletion in a single gene remained uninfected with HIV provided clear evidence that HIV infection requires a co-receptor in addition to CD4. This co-receptor is known as CCR5, and individuals with the 32-bp deletion lack the CCR5 receptor on the cell surface, making them resistant to infection with HIV strains that use CCR5 as a co-receptor.

In the Late 1990s, a Group of Individuals Was Discovered