The Flu Virus

THE FLU VIRUS HAEMAGGLUTININ is the H in HSN1. As one of the two main surface proteins, it is a key target for our immune system. Bird flu viruses have 16 types, of which three are also found in human flu viruses: H1, H2 and H3. Only H3 and H1 are now circulating in people. Immunity to one type will not protect you against another. Haemagglutinin got its name because it makes red blood cells clump together. Antibodies to it stop this happening, making H inhibition an old-fashioned but widespread test for flu NEURAMINIDASE, the N in HSN1, is the second main surface protein, and the other main target for the immune system. Nine types are known from birds and humans. Neuraminidase helps new viruses bud off from cells. Neuraminidase inhibitors such as The M1 MATRIX PROTEIN helps package new viral RNAS together after they have formed and transport them to the cell membrane, where a new virus buds off Tamiflu prevent this happening The M2 ION CHANNEL allows acid to enter the The LIPID ENVELOPE is picked up from the infected cell as a new virus virus, triggering the release of its genetic material. Adamantane antivirals, such as amantadine and rimantidine, block M2 and thus stop the virus replicating. But resistance evolves easily - it takes only a slight change in the shape of the channel The RNAS carry the instructions for making new viruses. There are eight strands and 10 genes altogether. They come packaged in nucleoproteins, along with the polymerase enzymes needed to make more copies of the RNAS buds off