Molecular characterization of Mycobacterium avium subsp. paratuberculosis (MAP) in dairy cattle of Nepal

Paratuberculosis caused by Mycobacterium avium subspecies paratuberculosis (MAP), is an economically important, endemic in many parts of the globe, and regarded as high prevalent disease of domestic and wild animals, especially ruminants, which is manifest as chronic granulomatous enteritis with decreased milk production, with serious cases resulting in progressive emaciation and death. Understanding the genetic variability of MAP, strains are important in diagnosis, epidemiological investigation, and therefore the formation of strategies for prevention and control of the disease. Thus, this study was designed to grasp the molecular characterization of MAP isolates of Nepal, as pioneer research of this area. Total of 46 MAP isolates obtained from cattle population of three different locations of dairy pocket areas of Chitwan, Nepal were typed using IS1311 polymerase chain reaction-restriction endonuclease analysis (PCR-REA) to research the MAP genotype of Nepal. The extracted DNA samples (n=46) were analyzed for the presence of MAP specific sequences (IS900) using PCR and DNA samples were further subjected to genotype differentiation using IS1311 PCR-REA and IS1311 L2 PCR-REA methods. All the DNA samples were positive for the entire three MAP specific sequences based PCRs. This study revealed that ‘Bison type’ strain is the single most prevalent MAP genotype circulating within the domestic cattle population of Nepal. IS1311 PCR-REA showed that MAP DNA samples of Nepal origin belonged to ‘Bison type’, whereas, IS1311 L2 PCR-REA method showed similarity with "Indian Bison type" and different restriction profiles of ‘Bison type’ genotype as compared to non-Indian strains. The study concludes that in Nepal, "Bison type" MAP stains was prevalent in all the MAP samples obtained from dairy cattle. These results have important epidemiological implications regarding control and prevention of paratuberculosis in Nepal.