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Analysis Of The Genome Of The Typical Ibv Strains In China And The Research Of The Pathogenicity

Posted on:2011-07-29Degree:MasterType:Thesis
Country:ChinaCandidate:B L YanFull Text:PDF
GTID:2143360305985406Subject:Prevention of Veterinary Medicine
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In recent years, there has been using the vaccine H120 extensively, but the kidney-type IBV occurs frequently, even the Mass-type IBV was isolated in 2007. In order to elucidate the characteristics and reseach the serotype of the predominant strains and evaluate the vaccine H120, 7 IBV typical strains were selected, which were isolated in China from 1997 to 2008. ck/CH/LDL/97â… was isolated from Proventriculus in Liao Ning province in 1997; tl/CH/LDT3/03 from kidney of a teal in Guang Dong province in 2003; ck/CH/LLN/98â… from Liao Ning province which was LX4-type and lack of 3a gene ; ck/CH/LSD/03â… from Shan Dong Province, which was also LX4-type, with 10aa deletion in 3a protein; ck/CH/LHLJ/07â…¦from the chicken vaccined by H120 and 4/91 in Qi Qihaer city Hei Longjiang Province in 2007,which was Mass-type. The ck/CH/LHB/08â… and ck/CH/LAH08â…¡isolated from He Bei Province and An Hui province respectively in 2008, were two viarants, which similarity of S1 gene compared with others except TCoV were 71.9%~87.7% and 69.9%~73.3% respectively.The genes of these strains were amplified through RT-PCR, then ligated to T vector, transformed into TG1 E.coli, cloned and seqnenced, analysed genes and genomes through computer softwares.It was found that the 5`UTR and 3`UTR sequence were conserved, which effects were practiced by their conserved second structure; the stem in pseudonodule were conserved but not loop; the fusion protein 1ab was cleaved into 15 small nsps; there were two mutations of amino-acid in ADRP:S130-L130, G132-R132, so maybe resulted into the lower activity; there no the cleavage site between nsp4 and nsp5 in ck/CH/LAH08â…¡, because of the mutation of A-T of the 8834th nt; there was a lack of 20aa in S gene, beceuse of the mutation of C-G of 23806thnt.The phylogenic trees which were constructed according to the genome, S1 gene, S2 gene, M gene, N gene, 3CLpaa sequence, showed that there were no recombination between all experimental strains; IBV genome order was the same as TCoV, but the lower similarty in sequence;the predominant strain in China was also the LX4-type strain; the vaccine of H120 could not provide complete protection; the characteristic of an IBV strain was reflected exactly only by the analysis of complete genome.The trial of the vaccine H120 against ck/CH/LHB/08â… and ck/CH/LAH08â…¡togather with the analysis of sequences showed that the Mass-type strains always existed though using H120 vaccine extensively in China.
Keywords/Search Tags:IBV, Immunoprotection, Mutation, Genome, Cross protection, Sequence analysis
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