Key result
Among 80 avian infectious bronchitis virus isolates from China during 2008-2009, 87.5% were nephropathogenic and predominantly belonged to the A2-like genotype, evolutionarily distant from current vaccine strains.
Observational (n=80)
May limit vaccine protection in Chinese poultry; leaves open need for genotype-matched IBV surveillance and reformulation.
BACKGROUND: The nephropathogenic avian infectious bronchitis (IB) caused unprecedented economic losses to the commercial chicken industry of China in 2008-2009. To investigate the prevalence of nephropathogenic IB in China, eighty IBV isolates from different provinces during 2008-2009 were identified by dwarf embryo test and RT-PCR. RESULTS: The strains were mostly isolated in winter and spring with a wide age range of IB outbreaks, from 4 to 69 days. By the virus recovery trials, 70/80 of the strains resulted in the deaths or distresses of birds from nephritis. To learn more about the molecular evolutionary characteristics of the circulating field strains, the coding region of major spike 1 (S1) protein gene of these strains was RT-PCR amplified and sequenced. Compared to the published representative strains, nucleotides and amino acids sequence analysis indicated that the S1 genes of these strains and the reference strains displayed homologies ranging from 75.1% to 99.8% and from 73.1% to 99.8% respectively. S1 protein of the major pandemic strains contained 540 or 542 amino acids with the cleavage site of HRRRR or RRFRR. Phylogenetic analysis revealed that recent field isolates of IBV in China were mostly belonged to A2-branch (QXIBV-branch) and HN08-branch, only one isolate was belonged to Gray-branch and M41-branch respectively. Most of the 80 strains showed evolutionarily distant from vaccine strains. CONCLUSIONS: The results of this study suggested that nephropathogenic IBVs were mainly A2-like strains in China during 2008-2009.
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Ji et al. (2011) conducted an observational in Avian infectious bronchitis (n=80). Avian infectious bronchitis virus (IBV) field isolates vs. Reference and vaccine strains was evaluated on Phylogenetic distribution and genotype of IBV isolates. Among 80 avian infectious bronchitis virus isolates from China during 2008-2009, 87.5% were nephropathogenic and predominantly belonged to the A2-like genotype, evolutionarily distant from current vaccine strains.
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