With respect to orthomyxoviruses,changes in antigenicity usually occur as a result of

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Antigenic changes in orthomyxoviruses are caused by both antigenic drift and antigenic shift. Antigenic drift occurs due to minor mutations in the viral genome, leading to small changes in the surface antigens (hemagglutinin and neuraminidase). In contrast, antigenic shift occurs due to major genetic changes, such as reassortment of genes from different influenza viruses infecting the same host, leading to the emergence of a novel influenza virus with new surface antigens. Frameshift mutations, on the other hand, can cause changes in the amino acid sequence of viral proteins but are not the primary mechanism of antigenic changes in orthomyxoviruses.

With Respect to Orthomyxoviruses,changes in Antigenicity Usually Occur as a Result