6 Present address: 1 Ph.D. Scholar, Department of Animal Science, University of Connectical, Stoors, USA. 2 Assistant Professor, Departent of Veterinary Microbiology and Biotechnology, College of Veternary and Animal Science. 3 Associate Professor, 4 Professor, Plant Biotechnology Centre, S.K. Rajasthan Agriculture University, Bikaner 334 001. Indian Journal of Animal Sciences 80 (11): 1062–65, November 2010 Capsular typing of Staphylococcus aureus isolates from cattle and goat mastitis by PCR targeting cap5K and cap8K genes A UPADHYAY 1 , A K KATARIA 2 , R SHARMA 3 and G SINGH 4 Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 335 501 India Received: 4 December 2009; Accepted: 23 August 2010 ABSTRACT The capsular typing of Staphylococcus aureus of bovine and caprine origin was carried out by polymerase chain reaction using primers specific for cap5K and cap8K genes. From cattle mastitis 60% of S. aureus were found to possess cap5K gene responsible for production of CP5 capsule and 20% of the isolates possessed cap8K gene responsible for biosynthesis of CP8 capsule. The rest 20% isolates did not produce amplicon with these primers and were considered non-CP5 and non-CP8 isolates. From goats, 30% of the isolates showed presence of cap5K gene and 20% of the isolates exhibited presence of cap 8K gene whereas 50% of the isolates were non-typable for cap5K or cap 8K genes. No polymorphism was observed in cap5K and cap8K genes observed by restriction fragment length polymorphism (RFLP) and by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis suggesting that the K genes of cap5 and cap8 gene cluster were highly conserved. Key words: Capsular typing, cap genes, Mastitis, PCR- SSCP, RFLP, Staphylococcus aureus Mastitis continues to be recognized as one of the major disease problems of dairy industry throughout the world and has been singled out as the most significant cause of economical loss in the dairy industry (Sordelli et al. 2000). Out of many different etiological agents, Staphylococcus aureus has been demonstrated as the most important pathogen in the causation of mastitis in cattle (Balakrishnan et al. 2004, Karimuribo et al. 2005) as well as in caprine (Moroni et al. 2005, Mørk et al . 2005, da Silva et al . 2006). The pathogenicity of the organism is largely determined by its ability to coordinately produce a plethora of extracellular toxins, enzymes, and surface antigens in bovine, ovine and caprine mastitis (Poutrel et al. 1988, Luong et al. 2003, O’Riordan and Lee 2004). As many as 11 different capsular types (1 through 11) have been demonstrated by Sompolinsky et al. (1985) in S. aureus isolates obtained from different sources. However, most clinical isolates from both human and bovine infection produce either capsular polysaccharide type5 (CP5) or capsular polysaccharide type8 (CP8) and considerable geographical variations exist in the prevalence of these types in bovine isolates (Sordelli et al. 2000, Tollersrud et al. 2000). Watts et al. (2005) revealed that capsulated isolates were more virulent than the capsule negative mutant. The antibody specific for capsular polysaccharides protect against S. aureus infection in murine model (Lee et al. 1997, Fattom et al. 2004) and these capsular polysaccharides offer promise as target antigens for a vaccine to prevent staphylococcal infections (O’Riordan and Lee 2004). The information regarding capsular types is important for the rational design of vaccine for the prevention of staphylococcal mastitis (Sordelli et al. 2000). The present paper puts on record genotyping of S. aureus regarding capsule type possessed by them. MATERIALS AND METHODS Samples: A total of 59 milk samples from cattle (41 indigenous of non-descript breed and 18 H-F crossbreds) and 41 samples from goats (Marwari) were collected for isolation of S. aureus. These animals with clinical mastitis were presented to Veterinary clinical complex, College of Veterinary and Animal Science, Bikaner. Isolation and identification of bacteria: The organisms were isolated and identified as described by Cowan and Steel (1975) and Quinn et al. (1994). Genotypic confirmation of all the S. aureus isolates was done by ribotyping for 23S rRNA as per Straub et al. (1999) using the two primers, Staur4 and Staur6 as used by them.