FIGURE 3-1 Diagrammatic Representation of an Influenza A Virus. The two major surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), along with small numbers of the matrix 2 (M2) ion channel protein, are embedded in a lipid bilayer. The matrix 1 (M1) protein underlies the envelope and interacts with the surface proteins and also with the ribonucleoproteins (RNPs). RNPs consist of the eight negative-stranded RNA segments and nucleoprotein (NP) and the polymerase complex heterotrimer (PB2, PB1, and PA). The nuclear export protein (NEP, or nonstructural protein 2, NS2) is contained within the virion, but the nonstructural protein 1 (NS1) is not.
SOURCE: Courtesy of Jeffery K. Taubenberger, NIH. This image is a work of the National Institutes of Health, taken or made during the course of an employee’s official duties. As a work of the U.S. federal government, the image is in the public domain.
enza sub-types that have been transmitted from wild birds to domesticated poultry.
Pigs are potential sources of new strains capable of infecting humans, as pigs are subject to infection by avian influenza, swine influenza, and human influenza. If a pig is infected simultaneously with influenza strains adapted to different species, it may thus serve as a mixing vessel wherein the interaction of the assortment of viruses may more likely give rise to a strain that is highly pathogenic for humans.