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Influenza Research Paper

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Influenza, commonly called "the flu," is an illness caused by RNA viruses that infect the respiratory tract of many animals, birds, and humans. Influenza viruses are found in body fluids such as saliva and mucous and commonly transmitted via tiny, air-born droplets created through sneezing and coughing. Depending on the conditions and temperature of the environment, the Influenza virus can remain infectious for up to one month. Transmission occurs as a new host comes into contact with viruses dispersed into the air or onto surfaces of objects. The main targets of the influenza virus are the columnar epithelial cells of the trachea, bronchi and bronchioles. HA binds to galactose-bound sialic acid on the surface of host cells. The HA binding …show more content…

Once tightly bound the virus is endocytosed via coated vesicles. The virus is transported into late endosomes which acidify their content and hence induce conformational rearrangement of HA exposing the fusiogenic peptide sequence. The loop region of the HA becomes a coiled coil that mediates membrane fusion. The release of viral genome into the cytoplasm also requires protons that are pumped from the acidic endosome into the virion interior via the matrix protein M2 that acts as a proton channel. Viral RNA dissociates from M1 and is then imported in an ATP-dependent manner into the nucleus for transcription and translation. In humans, the replication of the influenza virus is usually restricted to the airways epithelial cells due to the limited expression of a serine protease, produced by nonciliated bronchial epithelial cells and which cleaves the HA precursor in HA1 and HA2 polypeptides, rendering the virions infectious. Replication and virions production occurs within hours after virus entry. The viral ribonucleoprotein (vRNP) complexes are released from the endosomes into the cytoplasm and subsequently transported to the nucleus, where replication and transcription take …show more content…

Influenza type A viruses are divided into subtypes based on two proteins on the surface of the virus. These proteins are called hemagglutinin (HA) and neuraminidase (NA). There are 15 different HA subtypes and 9 different NA subtypes. There are three prominent subtypes of influenza A that are known to infect both birds and people. The first one is influenza A H5; there are nine known subtypes of H5 viruses (H5N1, H5N2, H5N3, H5N4, H5N5, H5N6, H5N7, H5N8, and H5N9). Most H5 viruses identified worldwide in wild birds and poultry are low pathogenic viruses, but occasionally highly pathogenic viruses have been detected. Sporadic H5 virus infection of humans, such as with Asian-origin highly pathogenic avian influenza A (H5N1) viruses currently circulating among poultry in Asia and the Middle East have been reported in 16 countries, often resulting in severe pneumonia with approximately 60% mortality worldwide. The second one is influenza A H7; there are nine known subtypes of H7 viruses (H7N1, H7N2, H7N3, H7N4, H7N5, H7N6, H7N7, H7N8, and H7N9). Most H7 viruses identified worldwide in wild birds and poultry are LPAI

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