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

Abstract

Five strains of infectious bronchitis virus isolated from commercial chickens from the state of Pennsylvania, USA during the years 1998 and 1999 were studied. The strains were selected for cross-challenge in specific pathogen free chickens and virus neutralization in chick embryos on the basis of partial S1 sequence amino acid identity values. The partial sequences analysed spanned the hypervariable amino terminus region of S1 from amino acid residues 48 to 219, based on the Beaudette strain. Using their S1 identity values, the strains represented a continuum of genetic, and thus antigenic, relationships. When compared with strain PA/5083/ 99, strain PA/Wolgemuth/98 had high sequence identity (96%) followed by PA/171/99 (85%), PA/5344/98 (70%) and PA/1220/98 (34%). The method of Archetti and Horsfall was used for calculating antigenic relatedness values of virus neutralization tests. The same formula was also applied to the percentage protection values of cross-challenge tests to derive protective relatedness values among the strains. The antigenic relatedness values, protective relatedness values, and the partial S1 sequence identity values were then analysed. The findings indicated partial S1 sequence identity values were more strongly correlated with protective relatedness values and than antigenic relatedness values.

Molecular characterization of avian infectious bronchitis virus strains from outbreaks in Argentina (2001–2008)

“…All of these isolates came from flocks vaccinated with Massachusetts-type vaccines, which produced insufficient protection against these field strains. As noted by Ladman et al (2006), there is a strongly correlation between the sequence including HVR1/2 of S1 with protective relatedness values, more than antigenic relatedness values based on virus neutralization and haemagglutination inhibition. These observations and the poor relationship between the Argentinean field isolates (from clusters A, B and C) and Massachusetts vaccine strains (average amino acidic identity of 73.6% between clusters A, B and C when compared with the Massachusetts group) could explain the failure of the Massachusetts serotype vaccination programmes to control IBV in these flocks (Gelb et al, 2005).…”

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

“…In the present study, less than 79.4 and 81.1% of nucleotide and amino acid similarities in S1 part of spike protein were shared, respectively, by the vaccine strains and isolate tl/CH/LDT3/03, which represents the major type of nephropathogenic IBV isolate present in the field in China, and was of a different serotype from the vaccine strains used here, indicating the various antigenic differences and larger evolutionary distances between vaccine strains and IBV strains present in the field. Although it has been reported that IBV S1 gene sequence comparison is a better predictor of challenge of immunity in chickens than serotyping by virus neutralization (Ladman et al, 2006), it is probably of more practical relevance in terms of control strategies to perform protection studies (protectotype) with the field isolates (Lohr, 1988;Cook et al, 1999). Of the eight vaccine strains sequenced in this study, four were selected for vaccination-challenge trials.…”

Coronavirus avian infectious bronchitis virus

“…First described in the 1930s in the USA, IB research has been dominated by the extensive genetic variation exhibited by the surface spike (S) protein gene, recognised half a century ago as antigenic variation. Specifically, virus neutralisation tests revealed the existence of serotypes (currently numbering dozens), which are poorly cross-protective [9,17,21,29,31,34,36,37,40,49,61,63,82].…”