Sequence analysis of infectious bronchitis virus isolates from the 1960s in the United States

Abstract

To better understand the molecular epidemiology of infectious bronchitis virus (IBV) in the United States following the introduction of commercial IBV vaccines, we sequenced the S1 and N structural protein genes of thirteen IBV field isolates collected in the 1960s. Analysis of the S1 sequence showed that seven isolates were of the Massachusetts (Mass) genotype, five were SE17, and one was of the Connecticut (Conn) genotype, suggesting that these three IBVs were circulating in commercial poultry raised in different regions in the United States during the 1960s. The S1 genes of Mass-type isolates had high levels of sequence variation, representing 81.3-81.9 % nucleotide (nt) and 77.3-78.7 % amino acid (aa) identity when compared to those of the SE17-type isolates. In contrast, the N genes from the same isolates were less variable (>92 % nt and >93 % aa identity) when compared to those of the SE17-type isolates. Phylogenetic analysis based on the S1 gene indicated that one isolate (L748) was more closely related to the Mass type. In contrast, phylogenetic analysis based on the N gene showed that L748 was more closely related to the SE17 type, indicating that there had been exchange of S1 genetic materials between Mass- and SE17-like viruses. In addition, the Mass-type isolates had high levels of sequence identity in the S1 gene compared with widely used modified live vaccines (Mass41, Ma5 and H120) and modern field strains from the USA and other countries, suggesting a common ancestor.

Phylogenetic and antigenic analysis of avian infectious bronchitis virus in southwestern China, 2012–2016

“…The molecular characteristics of IBVs vary around the world. Over the past ten years, epidemics of different genotypes have been observed in different countries or areas, such as the Variant-2 (IS/1494) and Mass types in Asia (Chen et al, 2015;Patel et al, 2015;Promkuntod et al, 2015;Seger et al, 2016;Xu et al, 2016b;Zou et al, 2010); the Mass and 793B types in the Middle East (Ganapathy et al, 2015;Hosseini et al, 2015;Najafi et al, 2016); the Mass, QX, and Italy-2 types in Africa (Fellahi et al, 2015a;Fellahi et al, 2015b;Knoetze et al, 2014); the 4/ 91, QX, and Italy-2 types in Europe (Kiss et al, 2015;Krapez et al, 2011); and the Mass type in South America (Balestrin et al, 2014) and North America (Mondal et al, 2013). The major genotype circulating around the world, however, is the QX type.…”

Global distributions and strain diversity of avian infectious bronchitis virus: a review

“…From the IBV field isolates collected in the 1960s, seven isolates belonged to Mass, five were SE17, and one was of the Connecticut (Conn) genotype. This shows that these viruses have long been in existence in this country (Jia et al, 2002;Mondal et al, 2013). The Delaware IBV variant, designated DE072 (Gelb et al, 1997), was first reported in 1992 and found to be distributed across the Northeastern USA.…”

S1 gene-based phylogeny of infectious bronchitis virus: An attempt to harmonize virus classification

“…The variant was isolated in 1967 in Georgia from a chicken flock with acute respiratory distress and was designated as SE-17 (Hopkins, 1969). A retrospective study identified respiratory SE-17 IBVs to be present in USA since 1965 (Mondal et al, 2013).…”