Influenza B virus

**Definition:** Species of the genus BETAINFLUENZAVIRUS that cause HUMAN INFLUENZA and other diseases primarily in humans. Antigenic variation is less extensive than in type A viruses (INFLUENZA A VIRUS) and consequently there is no basis for distinct subtypes or variants. Epidemics are less likely than with INFLUENZA A VIRUS and there have been no pandemics. Previously only found in humans, Influenza B virus has been isolated from seals which may constitute the animal reservoir from which humans are exposed.

**Tree numbers:** - B04.820.480.968.407.410

**Synonyms:** - FLUBV - Human Influenza B Virus - Influenza Viruses Type B - Orthomyxoviruses Type B - Influenza virus type B