Relationship between serotypes and genotypes based on the hypervariable region of the S1 gene of infectious bronchitis virus

Abstract

To group infectious bronchitis virus (IBV) isolates, a genetic grouping method based on hypervariable region 1 (HVR 1, nucleotides 168 to 197) was compared with that based on the whole S1 gene. Both methods resulted in the same grouping data. So the grouping method based on HVR 1 could represent the grouping method based on the whole S1 gene. Taiwan isolates could not be placed within the existing groups. In order to test the correlation between genotype and serotype, a one-way neutralization test was used to compare 9 Taiwan isolates selected from different genotypes with Massachusetts (Mass) (H120) and Connecticut (Conn) standard strains. In addition, a two-way cross-neutralization test was performed in embryonated eggs with the beta method (constant-virus, diluted-serum) and the reciprocal neutralization titers were calculated to give the relatedness (r) values. The results of two kinds of neutralizing tests showed that the serotypes of 9 isolates were different from Mass or Conn. Based on the r-values, 9 isolates were divided into two serotypes which were correlated with their genotypes. From pathogenicity tests, IBV Taiwan isolates could be divided into high, intermediate, and low pathogenicity according to their pathogenicity indexes. However, no relationship exists between pathotype and genotype. In conclusion, the genetic typing method based on HVR 1 can be used for typing IBV isolates.

Infectious bronchitis virus S1 gene sequence comparison is a better predictor of challenge of immunity in chickens than serotyping by virus neutralization

“…Amino acid substitutions in HVR and non-HVR regions of a 180-amino-acid residue S1 gene fragment were analysed (Figure 1 and Table 3). Consistent with other reports (Niesters et al ., 1986;Cavanagh et al ., 1988;Kusters et al ., 1989;Kingham et al ., 2000;Wang & Huang, 2000), amino acid substitutions were more numerous in the HVR than in the non-HVR. As expected, highly similar strains PA/5083/98, PA/Wolgemuth/98, and PA/171/99 had fewer overall amino acid changes than more diverse strains PA/5344/98 and PA/1220/98.…”

Existence of Avian Infectious Bronchitis Virus with a European-Prevalent 4/91 Genotype in Japan

“…Of these, the S1 glycoprotein is associated with virus attachment and is a major target of the neutralizing antibodies in chickens [5,8], so serotypic evolution in IBV is associated primarily with the sequences of the S1 glycoprotein [10,18]. Therefore, recent genetic grouping of IBV has been performed mainly on the basis of the nucleotide sequences of the S1 glycoprotein gene [9,11,12,17,18,20].Previously, our phylogenetic analysis of mainly hypervariable (HVR) regions of S1 glycoprotein genes revealed that Japanese IBV strains could be classified into five genetic groups, one of which is indigenous to Japan and can not be placed within the existing groups in other countries [14].In the present report, to define the epidemiology or relationships among recent IBV isolates in Japan during 2003-2007, we used essentially the same procedure in an attempt to characterize eight Japanese IBV isolates from chickens.The IBV isolates were obtained from prefecture-based regional animal hygiene service centers in Japan (Table 1). Most of the IBV specimens were isolated by two or three passages using 10-day-old embryonated chicken eggs.…”

“…Of these, the S1 glycoprotein is associated with virus attachment and is a major target of the neutralizing antibodies in chickens [5,8], so serotypic evolution in IBV is associated primarily with the sequences of the S1 glycoprotein [10,18]. Therefore, recent genetic grouping of IBV has been performed mainly on the basis of the nucleotide sequences of the S1 glycoprotein gene [9,11,12,17,18,20].…”

Serological Studies of Infectious Bronchitis Vaccines against Japanese Field Isolates of Homologous and Heterologous Genotypes

“…In a study on Taiwan isolates, field isolates were grouped into two genotypes by gene analysis of the HVR, and it was confirmed that the genotype correlates with serotype results [22]. Liu et al [15] and Gelb et al [7] reported the relationship between genotype and efficacy of a vaccine against field isolates and showed that vaccines with high S1 identity values are protective against field isolates.…”

“…The S1 glycoprotein is the major inducer of virus-neutralizing antibody and protection, and serotypic differences between IBV strains are associated primarily with sequences of the S1 glycoprotein [3,13,22]. Based on S1 analysis, Japanese field isolates have been classified into mainly three genotypes (JP-I, JP-II and JP-III) involving the indigenous genotype (JP-I) [16,20].…”