Avian Influenza A (H5N1) Virus
The circulation of the highly pathogenic avian influenzavirus (HPAI) H5N1 has intensified globally since 2021 with mass mortality in wild birds and poultry and incidental infections in mammals such as cattle.
The virus is a subtype of the influenza A virus belonging to the family Orthomyxoviridae which consists of viruses with a negative single-stranded RNA genome. The genome has eight segments encoding at least 11 different proteins, including hemagglutinin (HA) and neuraminidase (NA) glycoproteins.
Measles virus, a human pathogen, is in the genus Morbillivirus. It is an enveloped, single-stranded, non-segmented, negative-sense RNA virus. Its virions are pleomorphic (roughly spherical) in shape with a diameter of 300–500 nm. Parainfluenza and mumps viruses are within the genus Paramyxovirus, and the respiratory syncytial virus (RSV) and metapneumovirus are within the genus Pneumovirus.