Influenza B virus

Species of virus

Influenza B virus is the only species in the genus Betainfluenzavirus in the virus family Orthomyxoviridae. Influenza B virus is a negative-sense single-strand RNA virus known only to infect certain mammal species, including humans, ferrets, pigs, and seals. This limited host range is apparently responsible for the lack of influenza pandemics associated with influenza B virus, in contrast with those caused by the morphologically similar influenza A virus, as both mutate by both antigenic drift and reassortment.

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