Epidemiological classification of infectious bronchitis virus isolated in Korea between 1986 and 1997

Abstract

Forty Korean isolates and four reference strains of infectious bronchitis virus (IBV) were classified by reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism (RFLP) analysis. Each Korean isolate was isolated from different types of commercial chicken flocks between 1986 and 1997. RFLP patterns of an amplified DNA fragment (1722 bp) containing the S1 gene of IBV digested by restriction enzyme HaeIII showed that the 40 Korean isolates were classified into five genotypes, I to V. Six of them belonged to genotype I which had the same HaeIII and XcmI cleavage patterns with Massachusetts type (H120 and M41) but the other four genotypes had a different HaeIII cleavage pattern from the four reference IBV strains used in this study. Genotype III seemed to be the major type as 29 of the 40 isolates belonged to this type which was consistently found in the chicken flocks since 1990. On the other hand, genotypes II, IV and V were found in the field only in 1986,1995 and 1995, respectively. Five isolates selected from each of the five genotypes were inoculated into 1-day-old specific-pathogen-free chicks to evaluate their pathogenicity. Genotype III induced 50% mortality as well as severe renal urate deposition on the kidneys but the other four genotypes only showed respiratory distress at 1 to 2 days after inoculation. Live H120 vaccine protected chicks against challenge with isolates selected from genotype I, but not genotypes IV to V. A live KM91pl20 strain selected from major genotype III did protect chicks against challenge with isolates from genotype III, in addition to other genotypes, including two recent isolates of genotypes IV and V.

Genetic grouping of avian infectious bronchitis virus isolated in Brazil based on RT-PCR/RFLP analysis of the S1 gene

“…That molecular technique developed in the early of 90's (Kwon et al 1993) has been continuously applied to the analysis of IBV variants in the USA, Canada, China and Korea (Song et al 1998, Smati et al 2002, Gelb et al 2005, Jackwood et al 2005. The current results confirm the ability of RFLP analysis to screen and perform a genetic characterization of Brazilian IBV isolates and to indicate some relevant phenotypic variations related to the antigenicity of these viruses; nevertheless, further investigation is required in order to characterize changes caused by mutations and/or recombinations at the nucleotide and amino acid levels of the S1 glycoprotein of these isolates more accurately.…”

Detection of infectious bronchitis virus

“…Subsequently, the c-DNA is amplified many times using the PCR technique. After amplification, the PCR product is to be identified as originating from IBV by another technique such as sequencing (Andreasen et al, 1991;Zwaagstra et al, 1992), restriction enzyme fragment length polymorphism (RFLP) (Lin et al, 1991;Kwon et al, 1993b;Song et al, 1998), or hybridization (Jackwood et al, 1992;Zwaagstra et al, 1992;Kwon et al, 1993a). This confirmation is important to check whether the RT-PCR reaction was specific.…”

“…After amplification of cDNA of the S1 gene by PCR and purification by electrophoresis, the PCR product is digested with restriction enzymes that cut cDNA into fragments at certain highly specific cleavage sites (Song et al, 1998). The RFLP patterns are then compared with patterns of representatives of known serotypes.…”

Typing infectious bronchitis virus strains using reverse transcription-polymerase chain reaction and restriction fragment length polymorphism analysis to compare the 3′ 7.5 kb of their genomes

“…The use of reverse transcription-polymerase chain reaction (RT-PCR), in combination with restriction endonuclease fragment length polymorphism (RFLP) analysis (Lin et al, 1991;Kwon et al, 1993;Song et al, 1998) or with sequencing (Meulemans et al , 2001;Yu et al, 2001;Farsang et al, 2002;Gelb et al, 2005), has been described for discrimination of different IBV strains or for phylogenetic analysis. However, in these reports only a partial sequence (about 1.8 kb) of the gene for the spike protein (S1) was used.…”