Molecular Epidemiology of Avian Infectious Bronchitis in Brazil from 2007 to 2008 in Breeders, Broilers, and Layers

Abstract

Multiple lineages of Brazilian strains from 2007 to 2008 of avian infectious bronchitis virus (IBV) were detected in flocks of breeders, broilers, and layers. Organs samples from 20 IBV-positive flocks with variable clinical signs were submitted to the partial amplification of S gene (nucleotides 726-1071) of IBV. Fifteen of the 20 sequenced strains segregated in a unique Brazilian cluster subdivided in three subclusters (Brazil 01, 02, and 03). Whereas three strains could be classified as Massachusetts (Mass) genotype, the remaining two strains, originating from flocks with reproductive and respiratory disorders, grouped within the 4/91-793B genotype, a genotype that has not been detected before in Brazil. The potential relevance of the findings to the poultry industry is discussed because the low level of identity of the sequenced part of the S gene from 17 of 20 detected field strains and the vaccines of the Massachusetts serotype used suggest that the level of cross-protection by the Massachusetts vaccines might be low.

Increased level of protection of respiratory tract and kidney by combining different infectious bronchitis virus vaccines against challenge with nephropathogenic Brazilian genotype subcluster 4 strains

“…The results of the genotyping of the seven strains that could be re-isolated are shown in Figure 1. The three Brazilian subclusters (Brazil 01, 02 and 03) described by Villarreal et al (2010) are evident, while the seven strains from this study resulted in a fourth (Brazil 04) subcluster, all of them being close to the Brazilian strain IBV/Brazil/2007/ USP-19 (FJ791260). In Figure 1 strains Brazil Ck and Brazil Bk, both isolated from kidneys, grouped in a separate node when compared to those isolated from the enteric contents (Brazil Ae, Be, Ce and De) and the respiratory tract (Brazil Ar), with a 100% amino acid identity between them; a I332R amino acid mutation was found amongst the kidney and the enteric/respiratory strains, while V287G and Q291E differentiate the kidney/enteric and the respiratory strains (positions are given regarding the spike protein of the M41 strain Genbank accession number AY851295.1).…”

“…Genotyping of the seven IBV strains used in this study showed that all belonged to the general Brazilian genotype and that these strains were most close to the subcluster of strain IBV/Brazil/2007/USP-19 (Villarreal et al, 2010) (Figure 1). Interestingly, all S1-genes of the isolates that were detected in the different organs of the same chickens were not identical.…”

“…A single vaccination at 14 days of age with the heterologous 4/91 vaccine (Nobilis IB 4/91 of the 793B serotype) induced between 76% and 84% cross-protection against these strains, whereas the combination of both vaccines induced 87% and 88% protection against the two strains that were tested. More recent papers have reported the widespread existence of a unique Brazilian lineage which is predominant over other established types such as Mass, 4/91 and Connecticut IBV types (Brandão et al, 2009;Felippe et al, 2010;Villarreal et al, 2010;Chacon et al, 2011) with 63.4-79.3% nucleotide identity in the S gene compared to the Mass strain (Abreu et al, 2006;Villarreal et al, 2010;Chacon et al, 2011). Although these recent papers give us a valuable insight into the genetic epidemiology of IBV in Brazil, they lack data concerning serotyping, pathotyping and protection provided by vaccination against the recent Brazilian IBV strains.…”

Avian Infectious Bronchitis Virus: Immunogenicity Profiles and New Pathotypes in Brazil - Literature Review

“…Essas alterações genéticas acarretam mudanças relevantes nas características fenotípicas, como por exemplo, nas propriedades antigênicas e naquelas associadas à virulência e/ou à patogenicidade desse mesmo agente infeccioso. Para ilustrar melhor as conseqüencias da grande variabilidade que ocorre entre as estirpes do VBI, já foram descritos, em diversas partes do mundo, mais do que 20 sorotipos desse vírus (CHACÓN et al, 2011;JACKWOOD et al, 2012;DE WIT, 2017;MONTASSIER et al, 2006;MONTASSIER, 2010;VILLARREAL et al, 2010).…”

“…Além disso, a partir de 2000 e com base na análise das sequências de nucleotídeos do gene S1 de isolados de campo do VBI foram identificados, no Brasil, genótipos diferentes daqueles em que são classificadas as estirpes americanas, europeias, asiáticas e australianas do VBI (Figura 1) (BALESTRIN et al, 2014;CHACÓN et al, 2011;FELIPPE et al, 2010;FRAGA et al, 2013;MONTASSIER et al, 2006MONTASSIER et al, , 2012VILLARREAL et al, 2007VILLARREAL et al, , 2010. Além disso, foram também identificadas estirpes variantes brasileiras do VBI com relação à sequência de nucleotídeos do gene da nucleoproteína (N) (ABREU et al, 2006).…”