nrc

Molecular epidemiology and control of infectious bronchitis virus infection in intensive and extensive poultry farming in SriLanka

NRC Grant:  15-113

Dr. M. N. M. Fouzi
University of Peradeniya
Department of Farm Animal Production and Health
Faculty of Veterinary Medicine and Animal Science
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Area of Research:Farm Animal Health and Production – biotechnological aspect in poultry and fish diseases
Status:Ongoing

 

objectives

1) Determine the prevalence of IBV infection in the commercial egg layer, commercial broiler and back yard flocks in Sri Lanka.

2) Molecular Epidemiolog of the prevalent IBV strains targeting hyper variable S1 genes and phylogenetic analysis to determine the distance among field IBV strains and currently used vaccine strains.

3) Evaluation of the efficacy of currently used IBV vaccines in commercial layers and broiler chickens via serological, clinical and pathological monitoring.

overview

Infectious bronchitis outbreaks in vaccinated flocks in Sri Lanka are on rise, although vaccinations against IBV infections are commonly done in most of the commercial poultry farms in Sri Lanka. Furthermore, the prevalence of IBV has not been studied in any of the poultry farms such as the commercial layer, commercial broiler and back yard flocks in Sri Lanka. On other hand vaccination against IBV infections in chickens is widely practiced in commercial layer and broiler chicken industries, it is not known what IBV strains are circulating in Sri Lanka. The molecular information of currently circulating IBV strains is critical in order to know the validity of the currently used vaccines. More over the protective effects of current IBV vaccination programs have not been studied in the commercial layer and broiler industries in Srilanka. In contrary, production losses associated with IBV vaccine failures are on the rise. Therefore, the intended research is aimed to determine the prevalence of IBV infection in the commercial egg layer, commercial broiler and back yard flocks in Sri Lanka, characterize the IBV strains targeting hyper variable S1 genes and phylogenetic analysis, and to evaluate the efficacy of currently used IBV vaccines in commercial layers and broiler chickens via serological, clinical and pathological monitoring.

Serological monitoring of 30 layer, 30 broiler and 30 back yard premises will be conducted in all nine provinces of Sri Lanka during the project period. Sera from 10% of the birds from each commercial flock and all the birds in back yard flocks will be collected. IBV will be further evaluated to characterize the strains. As such, at the same time, we collect or pharyngeal and cloacal swabs IBV strain identification. When we observe respiratory disease, we planned to purchase these birds in order to conduct post-mortem examination and collection of lung, trachea, kidney, caecal tonsils and oviduct for virus identification. IIPCR by S1 genotype-specific RT PCR techniques (OIE Terrestrial Manual 2013, Chapter 2.3.3 Avian Infectious bronchitis) to determine the prevalence of serotypes and strains of IBV in chickens in Sri Lanka. This approach will provide sero-prevalence data and IBV genotype data indicating locally circulating IBV. We also administer a questionnaire for these flocks to get background information such as flock size, egg

production and other production parameters, respiratory disease and other disease history, vaccination history and so on.

Vaccinated flocks of broilers and layers will be monitored for sero conversion to the vaccines and also oropharyngeal and cloacae swabs will be collected to molecular diagnosis of IBV using S1 genotype-specific RT PCR technique weekly following the vaccination. Each of these premises we will maintain at least 15 birds as unvaccinated controls. IBV strains that will be genotyped under objective one will be further characterized using a new generation sequencing technique targeting the spike gene protein 1 of the IBV.

This approach will allow us to identify the suitability of the currently used IBV vaccination strategies in Sri Lanka. This will also allow us to recommend efficacious IBV vaccine strategies based on the local prevalence of IBV strains