Phylogenetic analysis of infectious bronchitis coronaviruses newly isolated in China, and pathogenicity and evaluation of protection induced by Massachusetts serotype H120 vaccine against QX-like strains

Abstract

Seventy-eight isolates of avian infectious bronchitis virus (IBV) were obtained from different field outbreaks in China in 2009 and genotyped with 34 reference strains. Four genotypes of IBV and three new isolates were identified by phylogenetic analysis and BLAST searches of the entire S1 gene. The results showed that most IBV strains that have circulated in China in recent years belong to the genotype of QX-like strains, and that they could be grouped further into two clusters, regardless of the level of genetic variation displayed. A study of pathogenicity that used three QX-like strains*ck/CH/LSD/091003, ck/CH/LDL/091022 and ck/CH/LJL/ 090330*showed that the isolates caused the most severe lesions in the kidneys and were therefore nephropathogenic strains with various levels of virulence in specific pathogen free chickens. A vaccinationÁ challenge test that was performed using the three QX-like strains showed that the commercially available H120 vaccine did not provide sufficient protection against challenge with the QX-like isolates, as demonstrated by comparison of the clinical signs, pathological lesions and virus recovery from the trachea and kidney of unvaccinatedÁchallenged and vaccinatedÁchallenged birds.

An overview of infectious bronchitis virus in chickens

“…In recent years some strains of IBV have caused proventriculitis (Yu et al, 2001;Gough et al, 2008;Benyeda et al, 2010;De Wit et al, 2011a;Sun et al, 2011) and enteritis (Jones, 2010a). Field infection with 793B has been associated with enteritis (Jones, 2010a).…”

Origin and evolution of LX4 genotype infectious bronchitis coronavirus in China

“…Of the 110 IBV strains, 50 were isolated previously Liu et al, 2006Liu et al, , 2008aLiu et al, ,b, 2009Han et al, 2011;Sun et al, 2011;Ma et al, 2012) and 60 were isolated in this study and purified as previously described (Chen et al, 2015). All the viruses were isolated from the chicken flocks suspected to be infected by IB.…”

“…Of the 110 IB viruses, the S1 gene of the 50 viruses isolated between 1995 and 2010 were sequenced previously Liu et al, 2006Liu et al, , 2008aLiu et al, ,b, 2009Han et al, 2011;Sun et al, 2011;Ma et al, 2012). In addition, the sequences from S2 to N genes of eight strains, including strains ck/CH/LHLJ/95I, ck/CH/LLN/98I, ck/CH/LHLJ/99I, ck/CH/LHLJ/02I, LX4, ck/CH/LJL/04I, ck/CH/LSD/03I and ck/CH/LXJ/02, were also sequenced previously (Liu et al, 2008b).…”

Protection conferred by a recombinant Marek’s disease virus that expresses the spike protein from infectious bronchitis virus in specific pathogen-free chicken

“…These serotypes arise from point mutations, insertions, deletions, and RNA recombination [3]. Multiple distinct genetic groups of IBV have been reported, but since 1996, the predominant field isolates in China have been classified as QX-like (LX4-type) [4-8]. QX-like IBVs are circulating in almost all of the countries in Europe, and these variants are frequently associated with cases of nephritis and false layer syndrome in chickens [9-14].…”