An enveloped virus is dependent on the envelope for its ability to infect a host cell. which virus most likely uses this mechanism?
hiv
polio
rabies
ebola

The right answer is HIV virus.

The HIV has on its surface about twenty trimers gp120 / gp41 (on its envelope) which will be used for the attachment of the virus on a cell receptor (CD4) of the target cells. These two proteins are encoded by the same gene (Env) and are synthesized as a precursor which will be glycosylated (addition of sugars) and cleaved by a protease.

Fixation of the trimer to the CD4 receptor induces a conformational change in the gp120 protein, which will increase its affinity for cellular coreceptors (CCR5 or CXCR4). Again, a conformational change occurs on the gp41 protein, which will allow the fusion of the virus and cell membranes.