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Influenza B virus
Medical expert of the article
Last reviewed: 04.07.2025
The structure of the influenza B virus virion is similar to that of the influenza A virus. The genome consists of 8 fragments encoding 3 nonstructural and 7 structural proteins. Several serovariants are distinguished by the antigenic properties of hemagglutinin and neuraminidase. The process of antigenic drift is less pronounced than in virus A. Influenza B viruses are the culprits of local outbreaks and epidemics; they do not cause pandemics.