tailieunhanh - Tổng quan về virus cúm A.PMH

vấn đề dịch tễ học, tiến hóa, hình thành genotype và tương đồng kháng nguyên-miễn dịch-vaccine. Cúm gia cầm là bệnh truyền nhiễm cấp tính của gia cầm, do nhóm virus cúm. | Avian influenza is a highly pathogenic and contagious disease caused by influenza A viruses, of which the causative agent belongs to the family Orthomyxoviridae, which can be transmitted from the infected animals to humans. There are 16 subtypes HA (H1 - H16) and 9 subtype NA (N1 - N9) to be known to go through reassortment to generate hundreds of variants of different virulence and pathgenicity. H5N1 highly pathogenic avian influenza (HPAI) has continued to pose a significant threat to both animal and human health. From late 2003 to June 2008, accumulated number of infected human cases is 385 with 243 deaths, presenting mortality rate, whereas Vietnam and Indonesia are the two countries of highest casualty. Unlike previous poultry outbreaks of highly pathogenic avian influenza due to H5 occurred from 1996 -2002 that they were controlled by depopulation with or without vaccination, the presently circulating A/H5N1 viruses (from 2003 - present) with formation of different genotypes, particularly genotype Z, have since been spreading from Southern China to other parts of the world. This is still a great threat to public health and defferent measures are needed to be developed to control. The virulence determinants for highly pathogenic avian influenza viruses are not limited to the best characterized virulence factor, the hemagglutinin (HA) cleavage site and the enzymatic activity of neuraminidase (NA), but rather are considered to be multigenic and capable to reassort gene segments for new viruses to emerge with different virulence characteristics, evidently encountered. Tens of thousand papers presenting the research work related to avian influenza A, in general, and to A/H5N1 in particular, ie. in recent 5 years, have been generated of which many come from the development of new technologies and vaccine(s) for immunization of poultry and for preparedness of pandemic possibly to occur in humans. In the view of epidemiology, evolution, genotype formation, antigenic variation to alter immunogenicity, sensitivity and resistance to pharmaceuticals, unlike other avian viruses, A/H5N1 virus tends to mutate in a fast way to generate new variants of new sublineages and tends to search for wider host spectrum to infect. Vaccine(s) from different reference strains of H5N1 have been developed using high-technologies including reverse-genetics, particularly, those which have been based on NIBRG-14 promise a good potentiality in control in future. Here, we review the basic understandings of epidemiological aspects, virology, molecular biology, evolutionary ocurrence, genotype formation, and current strategies for the development of H5N1 influenza vaccines, and possibilities of antigenic-immunogenic-vaccine relationships in Vietnam and worldwide. Summarized research works of the Vietnamese scientists and institutions regarding to research on the H5N1 endemics in Vietnam and on the materials of Vietnam origin including the contribution of the Institute of biotechnology on genomics/proteomics of the gene(s) of HA/NA and new generation vaccines are also introduced.