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The attenuated avian infectious bronchitis virus (IBV), derived from a wild strain (TW2575/98w) in chicken embryos after 75 passages, is designed as a commercial vaccine strain (TW2575/98vac) to control the disease in Taiwan. The differences in viral infectivity, replication efficiency, and genome sequences between TW2575/98w and TW2575/98vac were determined and compared. TW2575/98vac caused earlier death of chicken embryos and had higher viral replication efficiency. Thirty amino acid substitutions resulting from 44 mutated nucleotides in the viral genome were found in TW2575/98vac. All of the molecular variations lead to attenuation, found in TW2575/98, were not observed consistently in the other IBVs (TW2296/95, Ark/Ark-DPI/81, the Massachusetts strain, GA98/CWL0470/98, and CK/CH/LDL/97I) and vice versa. After further comparisons and evaluations from three aspects: (1) longitudinal analysis on the timing of variations appeared in specific homologous strain passages, (2) horizontal evaluations with the amino acid changes between wild and vaccine strains among the other 5 IBVs, and (3) inspection on alterations in the chemical characteristics of substituted amino acid residues in viral proteins, four amino acid substitutions [V342D in p87, S1493P and P2025S in HD1, as well as F2308Y in HD1(P41)] were selected as highly possible candidates for successful TW2575/98w attenuation. Our findings imply that molecular variations, which contribute to the successful attenuation of different IBVs, are diverse and not restricted to a fixed pattern or specific amino acid substitutions in viral proteins. In addition, four amino acid changes within the replicase gene-encoded proteins might be associated with TW2575/98 virus virulence.
Pubmed ID: 32232712
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NIH genetic sequence database that provides annotated collection of all publicly available DNA sequences for almost 280 000 formally described species (Jan 2014) .These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole-genome shotgun (WGS) and environmental sampling projects. Most submissions are made using web-based BankIt or standalone Sequin programs, and GenBank staff assigns accession numbers upon data receipt. It is part of International Nucleotide Sequence Database Collaboration and daily data exchange with European Nucleotide Archive (ENA) and DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through NCBI Entrez retrieval system, which integrates data from major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of GenBank database are available by FTP.
View all literature mentionsA commercial organization which provides assay technologies to isolate DNA, RNA, and proteins from any biological sample. Assay technologies are then used to make specific target biomolecules, such as the DNA of a specific virus, visible for subsequent analysis.
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