(in″floo-en´zә-vi″rәs) a former genus that included all of the viruses causing influenza , now reclassivied into separate genera called influenzavirus A , B , and C . A a genus of viruses of the family Orthomyxoviridae , containing the agent of influenza A. See also influenza virus . B a genus of viruses of the family Orthomyxoviridae , containing the agent of influenza B. See also influenza virus . C a genus of viruses of the family Orthomyxoviridae , containing the agent of influenza C. See also influenza virus .