The influenza A virus uses a sialic acid as a receptor for cellular entry. The chemical composition of the specific type of sialic acid that the virus interacts with differs among animal species. The avian influenza virus attaches to a specific sialic acid that is present in fowl epithelial cells but absent in human cells, whereas the human influenza virus can only attach to the type of sialic acid present in human respiratory epithelium. When pig epithelial cells, which contain both types of sialic acid, are infected with the combination of avian and human influenza A viruses, some of the new avian influenza viral particles become capable of attaching to human cells. However, the progeny of this new strain of avian influenza virus is still unable to attach to human epithelial cells. Which of the following phenomena best describes the change in the avian influenza virus in this experiment?

Question

The influenza A virus uses a sialic acid as a receptor for cellular entry.  The chemical composition of the specific type of sialic acid that the virus interacts with differs among animal species.  The avian influenza virus attaches to a specific sialic acid that is present in fowl epithelial cells but absent in human cells, whereas the human influenza virus can only attach to the type of sialic acid present in human respiratory epithelium.  When pig epithelial cells, which contain both types of sialic acid, are infected with the combination of avian and human influenza A viruses, some of the new avian influenza viral particles become capable of attaching to human cells.  However, the progeny of this new strain of avian influenza virus is still unable to attach to human epithelial cells.  Which of the following phenomena best describes the change in the avian influenza virus in this experiment?

Quizplus · Accepted Answer

Eductional Objective: Phenotypic mixing refers to coinfection of a host cell by 2 viral strains, resulting in progeny virions that contain nucleocapsid proteins from one strain and the unchanged parental genome of the other strain.  Because there is no change in the underlying viral genomes (no genetic exchange), the next generation of virions revert to their original, unmixed phenotypes.

The Influenza a Virus Uses a Sialic Acid as a Receptor