Molecular epidemiology of infectious bronchitis, newcastle disease and mycoplasma gallisepticum in broilers in Haryana
Abstract
Respiratory Diseases in poultry are large and economic group of disease. Three most economic
respiratory pathogens are Mycoplasma gallisepticum, Newcastle disease virus and Infectious Bronchitis virus.
Epidemiological analysis of data of four year period (2009-12) for Chronic Respiratory Disease revealed that it is
quite prevalent in the region with annual prevalence of 5-6 %. Maximum number of outbreaks of CRD were
reported in extremes of the weather (winters and summer).The variation in temperature mainly found to be the
important factor causation of CRD along with poor ventilation and presence of ammonia gas. Newcastle disease
showed annual prevalence of 2-5 %. Maximum outbreaks were in summer, followed by rainy season. Climatic
stress was found to major predisposing factor for ND which includes hot and humid environment. Dusty winds in
wheat harvesting season of the region may have their probable role in causation of disease. 16s rRNA gene PCR
successfully used for detection of M. gallisepticum, tissues like trachea and airsacs proved useful tissues for
detection without any need of culture or isolation. Sequence analysis of these samples showed closer homology to
US strains as compared to those reported from Tamil Naidu strains. RT-PCR for F-gene and S1 gene was
standardized for detection of NDV and IB respectively. Real time RT-PCR for F-gene was standardized and used
for screening of the RNA samples extracted from Trachea, Lungs and Caecal tonsils. Real time successfully
detected the NDV in thirteen samples out of forty. It was found 100 times more sensitive than conventional RTPCR
for detection of NDV. Therefore, it can be used as rapid screening tool for diagnosing NDV. In conclusion,
present study reports the effect of season on CRD and NDV with role of different pre-disposing factors, PCR for
MG detection using tissues directly, comparative sensitivity of RT-PCR and real time RT-PCR for NDV detection
and usage of real time RT-PCR for rapid detection of NDV.
MAJOR
Description
Keywords
Epidemiology, PCR, Mycoplasma gallisepticum, Newcastle disease, Infectious Bronchitis