tailieunhanh - Báo cáo y học: " Avian influenza A (H9N2): computational molecular analysis and phylogenetic characterization of viral surface proteins isolated between 1997 and 2009 from the human population"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Avian influenza A (H9N2): computational molecular analysis and phylogenetic characterization of viral surface proteins isolated between 1997 and 2009 from the human population | Butt et al. Virology Journal 2010 7 319 http content 7 1 319 VIROLOGY JOURNAL RESEARCH Open Access Avian influenza A H9N2 computational molecular analysis and phylogenetic characterization of viral surface proteins isolated between 1997 and 2009 from the human population Azeem M Butt1 Samerene Siddique1 Muhammad Idrees1 Yigang Tong2 Abstract Background H9N2 avian influenza A viruses have become panzootic in Eurasia over the last decade and have caused several human infections in Asia since 1998. To study their evolution and zoonotic potential we conducted an in silico analysis of H9N2 viruses that have infected humans between 1997 and 2009 and identified potential novel reassortments. Results A total of 22 hemagglutinin HA and neuraminidase NA nucleotide and deduced amino acid sequences were retrieved from the NCBI flu database. It was identified that mature peptide sequences of HA genes isolated from humans in 2009 had glutamine at position 226 H3 of the receptor binding site indicating a preference to bind to the human a 2-6 sialic acid receptors which is different from previously isolated viruses and studies where the presence of leucine at the same position contributes to preference for human receptors and presence of glutamine towards avian receptors. Similarly strains isolated in 2009 possessed new motif R-S-N-R in spite of typical R-S-S-R at the cleavage site of HA which isn t reported before for H9N2 cases in humans. Other changes involved loss addition and variations in potential glycosylation sites as well as in predicted epitopes. The results of phylogenetic analysis indicated that HA and NA gene segments of H9N2 including those from current and proposed vaccine strains belong to two different Eurasian phylogenetic lineages confirming possible genetic reassortments. Conclusions These findings support the continuous evolution of avian H9N2 viruses towards human as host and are in favor of effective surveillance and better .