Orthomyxovirus

Orthomyxovirus is a genus of negative-sense, single-stranded, segmented RNA viruses, transmitted by droplets made when people with flu cough, sneeze, or talk, causing respiratory tract infections. This viral family includes seven genera with influenza (Flu) being studied most. Influenza viruses can be divided into three classes, A, B, and C, largely based upon conserved antigenic differences in the internal nucleoprotein (NP). Influenza subtypes are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). Viral hemagglutinin (HA) is the common target for vaccine development. 

Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. It represents a year-round disease. Avian influenza virus primarily infects birds but also humans, such as highly pathogenic avian influenza (HPAI) A (H5N1) virus, which requires BSL-4 labs to handle the live virus.