Molecular Characterization of Avibacterium paragallinarum Isolated from Poultry Flocks of India

摘要

Infectious Coryza (IC) is one of the highly infectious and contagious respiratory tract disease of poultry caused by Avibacterium paragallinarum . It has emerged as one of the major problem of commercial poultry industry worldwide due to huge economic losses in terms of increased number of culls and significant reduction in egg production (10-40%). Scarce reports are available regarding prevalence of Av. paragallinarum from India. The present study was designed to characterize the Indian Av. paragallinarum serovars at molecular level based on the Restriction Fragment Length Polymorphism (RFLP) of 16S ribosomal gene amplified, amplified 16S ribosomal DNA restriction analysis (ARDRA), sequencing of haemagglutinin antigen (hagA) gene and phylogenetic analysis . Four culture positive isolates of Av. paragallinarum , recovered from different geographical locations of the country, were confirmed by species specific HPG-2 Polymerase Chain Reaction (PCR) and other 10 nasal sinus swabs were found positive by direct HPG-2 PCR. ARDRA technique amplified product of 16S ribosomal DNA (r-DNA) showed identical Restriction Enzyme Analysis (REA) pattern for all the isolates indicating presence of similar operons in 16S ribosomal gene. The ?hagA? encoding a haemagglutinin antigen of Av. paragallinarum from all the field isolates revealed homology between Australian A and C serovar strain but did not cluster according to Page?s serovar scheme of classification. The present study is first in its nature regarding the molecular characterisation of Indian field isolates of Av. paragallinarum and provides valuable information regarding their genetic nature. Further extensive molecular studies will help both in the identification of field isolates and devising appropriate prevention and control measures for this important pathogen of poultry.