tailieunhanh - Báo cáo sinh học: " What have we found out about the influenza A (H1N1) 2009 pandemic virus"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Q&A: What have we found out about the influenza A (H1N1) 2009 pandemic virus? | Journal of Biology Question Answer Q A What have we found out about the influenza A H1N1 2009 pandemic virus Stephen J Turner Lorena E Brown Peter C Doherty and Anne Kelso The 1918 pandemic influenza virus is said to have started by causing relatively mild disease in the summer but to have become more severe in the winter. Do we know why and might influenza A H1N1 2009 do the same It is not clear precisely what changes resulted in the increased severity of infection during the second wave of the 1918 Spanish influenza pandemic. Certainly the occurrence of multiple waves of influenza infection in the same year is unusual and one possibility is progressive adaptation of the 1918 Spanish influenza virus to its new human host 1 . Molecular analysis for example suggests that the virus that emerged during the second wave in the Northern hemisphere had undergone changes in the hemagglutinin HA binding site that increased binding specificity for human receptors 2 . This is presumed to have affected the replicative capacity and therefore the pathogenicity of the virus. The 1918 Spanish influenza virus also encoded a non-structural 1 NS1 protein capable of blocking interferon production and thus prevention of viral replication by the host 3 . Changes in the NS1 protein may also have contributed to host adaptation and increased virulence 1 . Importantly however two of the features that account for the virulence of the highly pathogenic avian influenza A H5N1 viruses are not present either in the Spanish influenza virus or in the current pandemic influenza A H1N1 2009 virus 4 . These are a lysine at position 627 of the polymerase basic subunit 2 and glutamic acid in position 92 of NS1 that at least in animal models of infection increase the replicative capacity of the virus and block host inhibition of viral replication respectively 5 6 . As the H1N1 2009 pandemic virus continues to spread the opportunities for adaptation that increases virulence in the human host also .

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