What term describes small changes in viral genes that can affect a virus's surface proteins?

The term that describes small changes in viral genes, which can impact the structure and function of a virus's surface proteins, is known as antigenic drift. This phenomenon typically occurs through point mutations during viral replication, leading to slight variations in the virus's antigens. These minor genetic alterations can help the virus evade the host's immune response, making it more challenging for the immune system to recognize and respond effectively to the infection.

Antigenic drift is especially significant in viruses like influenza, where these small changes can lead to new strains that are not well recognized by the immune system, thereby complicating vaccine effectiveness. This is distinct from antigenic shift, which involves the reassortment or recombination of genetic material from different strains, resulting in more significant changes.

Mutation, while relevant to genetic change generally, does not specifically refer to the gradual, small changes that alter surface proteins in the context of viral immunity. Gene recombination refers to the process by which segments of DNA or RNA are rearranged, leading to new genetic combinations, but it does not specifically describe the minor alterations that characterize antigenic drift.