Submitted to: Canadian Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2005
Publication Date: 10/1/2005
Citation: Lee, J., Obrien, C.N., Guidry, A.J., Paape, M.J., Schafer-Weaver, K.A., Zhao, X. 2005. The effect of a trivalent vaccine against staphylococcus aureus mastitis on lymphocyte subpopulations, antibody production and neutrophil phagocytosis. Canadian Journal of Veterinary Research. 69(1):11-18.
Interpretive Summary: Staphylococcus aureus is the most frequently isolated pathogen from cases of mastitis. It accounts for 19 to 40% of all cases of mastitis represents approximately 35% of the economic loss due to mastitis. The cure rate of antibiotic treatment is low, and the infections often becomes chronic. These is attributed to the ability of S. aureus to locate intracellularly and survive antibiotic treatments. To date, effective prevention of S. aureus mastitis has not been achieved. Many efforts have been made to develop an effective vaccine to prevent S. aureus mastitis in the past decades. Numerous strategies, including immunization with killed bacteria cells or their virulent factors, have been practiced. However, these vaccines have shown poor efficiency in preventing new intramammary infections caused by S. aureus. Neutrophils, a type of white blood cell, are recruited to sites of infections and play a crucial role in bacterial clearance. S. aureus is able to produce a slime that masks their recognition by neutrophils. This makes S. aureus more resistant to the host immune system. A new vaccine developed by researchers in the US and Canada allows neutrophils to recognize the slime covering S. aureus and allows the neutrophils to ingest the bacteria. The vaccine may help dairymen rid their herds of mastitis caused by S. aureus.
Technical Abstract: The effect of a novel bovine mastitis trivalent vaccine, containing Staphylococcus aureus capsular polysaccharide type 5 (T5), 8 (T8) and 336 (T336), on lymphocyte subpopulations, antibody production, and neutrophil phagocytosis was evaluated. Twenty pregnant heifers were immunized with either the trivalent alone (T), trivalent emulsified in Freund's incomplete adjuvant (FICA) (T + F), trivalent in aluminum hydroxide (ALUM) (T + A), or adjuvant only (FICA), 30 days before the expected calving date followed by 2 boosts in a 2-week interval. Compared to FICA, serum antigen-specific IgG1 and IgG2 were significantly increased in all the vaccinated groups before parturition and sustained until 3 weeks postpartum. In comparison with the trivalent alone, formulation with either adjuvant enhanced production of IgG2, but not IgG1. Immune sera which contained the highest titer of antibodies slightly increased neutrophil phagocytosis to the three serotypes of killed S. aureus. The percentage of CD4+ lymphocyte was significantly higher in vaccinated groups than that of FICA 4 weeks after the primary immunization. In comparison with FICA, cows inoculated with trivalent vaccine and adjuvants had an increased percentage of CD8+ lymphocytes at two time points, 2 weeks before and after calving. Our results indicated that the trivalent vaccine, with or without adjuvants, dominantly elicited Th2 type immune responses which are less effective in preventing S. aureus mastitis.