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Nationwide Survey of Infectious Bronchitis Virus on Layer Farms in Japan During 2015
Masahiko Kaneda1,2,3, Sayaka Takahashi3,4, Ikunori Naito1,2
1The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu City, Gifu 501-1193, Japan.
Abstract:
After accumulating data through a nationwide survey, we characterized the recent prevalences and geographic distributions of various genotypes of infectious bronchitis virus (IBV) on layer farms in Japan. Reverse transcription PCR analysis of fecal samples revealed the presence of the IBV nucleoprotein (N) gene on approximately 30% of the farms surveyed. N-gene detection rates were higher in the Chugoku and Kyushu regions than in the remaining surveyed regions. Phylogenetic analysis of S1 gene sequences revealed that JP-I, JP-II, JP-III, and Massachusetts genotypes were particularly prevalent, with JP-I isolated throughout the country. Additionally, JP-II was the genotype detected most frequently in Chugoku, and JP-III was the most frequent in Kyushu. Unlike the previous results obtained in 1998 through 2003, the European-prevalent 4/91 genotype was no longer circulating in Japan. Moreover, the number of prefectures where multiple genotypes were detected simultaneously increased during that time.
Insights
Infectious Bronchitis Virus (IBV) N-gene was detected on 30% of Japanese layer farms, with higher rates in Chugoku and Kyushu. Genotypes JP-I, JP-II, and JP-III are now prevalent, replacing the 4/91 genotype.
Area of Science:
- Veterinary Virology
- Avian Pathology
- Molecular Epidemiology
Background:
- Infectious Bronchitis Virus (IBV) poses a significant threat to the poultry industry worldwide.
- Understanding the prevalence and genetic diversity of IBV is crucial for effective disease control in layer farms.
- Previous studies in Japan (1998-2003) indicated the circulation of specific IBV genotypes, including the 4/91 strain.
Purpose of the Study:
- To characterize the recent prevalence and geographic distribution of IBV genotypes in Japanese layer farms.
- To identify shifts in IBV genotype prevalence compared to historical data.
- To provide updated epidemiological information for IBV control strategies.
Main Methods:
- Nationwide survey of layer farms across Japan.
- Reverse transcription PCR (RT-PCR) for detecting the IBV nucleoprotein (N) gene in fecal samples.
- Phylogenetic analysis of the IBV S1 gene sequences for genotype identification.
Main Results:
- The IBV N-gene was detected on approximately 30% of surveyed farms.
- Higher N-gene detection rates were observed in the Chugoku and Kyushu regions.
- Prevalent genotypes included JP-I, JP-II, JP-III, and Massachusetts; JP-I was found nationwide.
- JP-II was most frequent in Chugoku, and JP-III in Kyushu.
- The European 4/91 genotype was no longer detected.
- An increase in the number of prefectures with multiple simultaneous IBV genotypes was observed.
Conclusions:
- Current IBV genotypes in Japanese layer farms show a distinct pattern compared to previous years.
- Regional variations in genotype prevalence (Chugoku, Kyushu) are significant.
- The disappearance of the 4/91 genotype and the emergence of multiple genotypes highlight the dynamic nature of IBV evolution and circulation in Japan.
