Investigations on Staphylococcal Protein A and Immunoglobulin G3 Allotype Gene Polymorphism in Mastitic Cattle and Buffaloes

Abstract

Mastitis is a well known disease in dairy animals and S. aureus has been recognized as most common cause of intramammary infection. The present work evaluated pathogenic factors, and antibiotic resistance of S. aureus and potential role of IgG3 allotypes in mastitic animals. In order, isolates (n=346) of S. aureus were obtained from mastitic animals which were identified using biochemical and molecular methods. Further, isolates assayed for antibiotic-resistant showed that 27.2% were susceptible to all the antimicrobials used. Resistance remained high to tetracycline (33.8%), gentamicin (28%), kanamycin (27.5%), streptomycin (27.5%), erythromycin (24.6%) amikacin (24%) and penicillin-G (22.3%). Higher prevalence of MRSA (9.5%) was observed. Antibiotic-resistance genes MsrA (30.3%), MsrB (46.5%), LinA (54.3%), TetK (32.1%), AacA-D (27.2%) and MecA (7.5%) found in predominance and 69.3% of isolates expressed at least one kind of gene. Moreover, pathogenic factor genes Coa (94%), ClfA (94.5%), Ig-binding (100%), Agr (100%), FnbA (100%), Eno (100%), Hla (100%), Nuc (100%), Map (81.7%), Fib (61.8%), Cap5 (59.5%) and Ebp (57.5%) were observed in high proportions. SpA gene revealed polymorphism (3-12R) and highest proportion (78.6%) of 7R and 8R was found in isolates; whereas 4R (0.3%), 12R (0.6%) and 3R (0.9%) remained low. The distribution of IgG3 allotypes in mastitic animals (n=152) was carried out using PCR-RFLP. Amplicons of IgG3 assayed with endonuclease enzymes BsaAI, BstYI and HphI revealed polymorphism and significant association with SpA repeats. Conclusively, genetic frame of S. aureus isolates may be useful for culling or segregation of animals. Further, association of IgG3 and SpA gene may be useful in animal breeding evaluation strategies.