Tyler Jw

Advances in the Therapy for Mastitis

Methods to enhance mammary resistance to bacterial infection and to reduce the effects of existing infections without the use of antimicrobial agents are becoming more attractive, primarily because of increasing pressure from consumers and regulatory agencies to decrease the risk of drug residues in milk. Because of the difficulty in obtaining satisfactory results with existing drug formulations, new approaches in the treatment of mastitis should emphasize better understanding of mammary gland pharmacokinetics, ameliorating the pathologic effects of infection, and enhancing natural defenses. Efficacy studies should emphasize milk production and long-term survival of cows to allow economic evaluations.

Immunization and Immunotherapy for Mastitis

Immunization and immunotherapy for mastitis are active areas of investigation. The past decade has seen development of effective and economical R-mutant vaccines for gram-negative mastitis. These vaccines doubtless will prove beneficial on well managed dairies that have eradicated contagious mastitis pathogens. Development of vaccines for other mastitis pathogens has been noticeably slower. A commercially available Staphylococcus aureus vaccine appears to reduce the frequency and severity of clinical episodes, but probably has minimal impact on the incidence or prevalence of infection. This product has not been extensively studied. The recent recognition of virulence factors produced in vivo by Staphylococcus aureus may provide a breakthrough in the development and production of Staphylococcus aureus vaccines. Bacterins employing this principle presently are not commercially available, however. In the case of all contagious mastitis pathogens (Streptococcus agalactiae, Staphylococcus aureus, and Mycoplasma spp.), traditional control and eradication efforts (teat dip, dry cow therapy, culling programs) likely will prove preferable to long-term immunization. Ongoing research may provide more efficacious vaccines for these mastitis syndromes. Immunostimulants are an active area of research. Although leukopoietic factors appear promising as immunostimulants, no compound has clearly demonstrated efficacy in either the prevention or treatment of bovine mastitis.

Cross-reactive affinity purification of immunoglobulin recognizing common gram-negative bacterial core antigens

A procedure isolating immunoglobulins specific for common gram-negative bacterial core antigens is described. A polyclonal reagent was purified by ammonium sulfate precipitation, dialysis, and column affinity chromatography. The initial vaccinal antigen was an Ra mutant Escherichia coli O111:B4 (strain J5). The capture antigen was lipopolysaccharide derived from an Ra mutant, Salmonella typhimurium TV119 covalently-linked to an agarose matrix. Column eluants were characterized in terms of total protein concentration, IgG concentration, and EIA titer recognizing E. coli (J5). Low protein, low IgG, high EIA reading fractions were isolated, demonstrating the utility of the described technique to purify broad spectrum cross-reactive immunoglobulin reagents.