Genetic diversity of avian infectious bronchitis coronavirus strains isolated in China between 1995 and 2004

Abstract

Twenty-six avian infectious bronchitis (IB) viruses (IBV) were isolated from outbreaks in chickens in China between 1995 and 2004. They were characterized by comparison with twenty-six Chinese reference strains and five other IBV strains. Chinese IBVs, which were mainly nephropathogenic, were placed into seven genotypes. Fourteen Chinese IBV isolates were placed in genotype I, having small evolutionary distances from each other. Genotype II included 6 strains that were isolated in the 1990s in China. Genotype III consisted of eight Chinese isolates that showed close relationship with Korean IBV isolates. Another eight IBV isolates clustered in genotype IV and showed larger evolutionary distances. The Massachusetts serotype was present in China in 1990s and was in a separate genotype. Two isolates, HN99 and CK/CH/LHN/00I, which might be a reisolation of vaccine strains, clustered into genotype VI. Four Chinese IBV isolates formed another genotype and showed larger evolutionary distances from other Chinese IBV genotypes (genotype VII). IBVs in same genotypes showed more than 90% amino acid sequence similarities, whereas most of the viruses in different genotypes showed less than 90%. The results showed that IBVs in China came from genetic changes both in IBV populations that existed before the advent of vaccination and in the viruses that were introduced through live vaccines. IBVs showing various genetic differences are cocirculating in China.

Infectious bronchitis virus: S1 gene characteristics of vaccines used in China and efficacy of vaccination against heterologous strains from China

“…The RNA was air-dried for 2 to 10 min, redissolved in 30 ml RNase-free water and stored at (/708C until use. Reverse transcription was carried out in a 40 ml reaction mixture containing 20 ml RNA using IBV genomic antisense IBV-212 oligonucleotide (Table 2), as described elsewhere (Liu et al, 2006).…”

“…Therefore, two genome-sense oligonucleotides *S1Uni2 (Adzhar et al, 1997) and IBV-87 (Liu et al, 2006), as summarized in Table 2 *were used with IBV-212 as the antisense primer for PCR amplification of the entire S1 protein genes of vaccine virus strains. The PCR profiles involved an initial denaturation for 5 min at 958C followed by 30 cycles of denaturation at 948C for 1 min, annealing at 508C for 1 min, and polymerization at 728C for 2 min.…”

“…The nucleotide and amino acid sequences of the S1 protein gene of the eight IB vaccine virus strains were assembled, aligned, and compared with reference IBV strains using the MEGALIGN program in DNAStar. Phylogenetic analysis of the nucleotide sequences and the deduced amino acid sequences of the S1 protein gene was performed by the Clustal Vmethod using DNAStar software (Liu et al ., 2006). Fifteen Chinese IBV field isolates representing different IBV genotypes (Liu et al ., 2006) were chosen for comparison with our eight vaccine strains.…”

“…Phylogenetic analysis of the nucleotide sequences and the deduced amino acid sequences of the S1 protein gene was performed by the Clustal Vmethod using DNAStar software (Liu et al ., 2006). Fifteen Chinese IBV field isolates representing different IBV genotypes (Liu et al ., 2006) were chosen for comparison with our eight vaccine strains. The accession numbers for these S1 genes of IBV isolates were: ZJ971 (AF352313), JL/ 97/01 (AF258780), HN99 (AY775551), CK/CH/LHN/00I (DQ167143), BJ (AY319651), CK/CH/LHLJ/95I (DQ167141), CK/CH/LHLJ/04V (DQ167139), LX4 (AY189157), CK/CH/LGD/04III (DQ167135), tl/ CH/LDT3/03 (AY702975), CK/CH/LSC/95I (DQ167146), CK/CH/ LTJ/95I (DQ167151), J (AF352312), J2 (AF286303), and CK/CH/ LDL/97I (DQ068701).…”

“…In China, IB *especially nephropathopathogenic IB *is still a major problem in the poultry industry Liu et al, 2006). Initial molecular characterization of the Chinese IBV isolates resulted in the identification of a new genotype by comparing the S1 genes with those of IBVs in America, European countries, and Japan and IBV isolates in Taiwan .…”