Final answer:
The CCR5-delta 32 mutation in the gene encoding the CCR5 receptor on T cells provides resistance to HIV by preventing the virus from effectively binding and entering the host cell, affecting the receptor binding step of the virus life cycle.
Step-by-step explanation:
Mutations in viral genes can alter receptor binding and thus the ability of the virus to infect host cells. Specifically, in the context of HIV and the Togaviridae family, mutations in the genes encoding envelope proteins can affect the interaction with cell surface receptors like CCR5 or CD4, which are crucial for the virus to enter T cells. The CCR5-delta 32 mutation is one such example, where a deletion mutation in the gene encoding the CCR5 receptor provides resistance to HIV infection by preventing effective viral binding and entry. This mutation disrupts the receptor binding step of the HIV life cycle. Viruses like the Togaviridae family and HIV have evolved to utilize molecules like CD4 and CCR5 on T lymphocytes to attach and penetrate the host cells, enabling their replication.