| Mastitis is one of the most important diseases that lead serious loss to the milk industry. It's infectious universally in the herds, mainly caused by bacteria. Because of the various pathogens, effective control measures are still to be found. Currently, antibiotic therapies are main controlling methods that lead to decrease of milk quality. With the increasing public concern over food safety and the emergence of pathogenic strains resistance to antibiotics, it is proper to look for new measures to control bovine mastitis. It's approved by scientists of many countries that it's urgent to develop vaccine against mastitis of dairy cows. A new Staphylococcus aureus(S. aureus) emulsive inactive vaccine was developed in this paper. The main research results as followed:Fifty-three strains of S. aureus were isolated from 93 milk samples of dairy cows suffering from mastitis so it's the main pathogen in the three cow fields in Nanjing region. From the isolates six classical ones were selected to analysis with the biochemical character and the inherited stability. Furthermore the other pathogenic factors of the six isolates were detected, such as coagulase, antimicrobial resistance factors and hemolysin, etc. Because the S. aureus isolates that lead to mastitis of dairy cows can also cause the arthritis of mice, the mouse arthritis model for bovine mastitis was established. With the mouse model, the pathogenicity of four typical isolates was evaluated, and the result showed the XG-2 was the most virulent isolate in the four.To select typical antigen-spectrum strains, crushed bacterial cells of 6 S. aureus isolates, 2 S. hemolyticus isolates, 3 S. epidermidis isolates and 4 S. saprophyticus isolates were processed with SDS-PAGE. The results showed that the protein bands of S. aureus were more and thicker than the other coagluase negative Staphylococcus(CNS). Mixture of whole bacterial cells of four S. aureus isolates were chosen to inoculate rabbit, and the hyperimmunized serum was used in the Western-blot assay to analyze the cross protective antigens of the isolates. Low concentration of live bacteria of the four S. aureus isolates was applied to inoculate mice subcutaneous respectively. S. aureus antigen-based indirect ELISA is established to detect the antibody titers and the cross protective antibody in micesera. Two typical antigen-spectrum isolates TQ-1 and XG-2 were suitable vaccine strains.The bacterial cells of two S. aureus strains TQ-1 and XG-2 were inactivated with 0.8% formaldehydes. Appropriate adjunvant was selected to make a S. aureus emulsive unlived vaccine against mastitis of dairy cows and the new vaccine was tested with stability, sterility and safety. The results showed the vaccine against mastitis of cows emulsified with ISA206 was steady, germfree and safe. With the mouse arthritis model, serology test and challenge test were processed after three times immunization with the new vaccine. The results showed after three times inoculation with the new vaccine, high specific antibody titers could be elicited and effective protection against homogenate and heterogenate S. aureus could be gained.To evaluate the effect of the new emulsive inactive vaccine, field trial was carried on. The whole bacterial cells of S. aureus antigen-based indirect ELISA was established to detect the antibody titers of sera and milk whey of dairy cows. After 3 times vaccination, the antibody titers were evaluated, and the results indicated that the antibody titers of sera and milk whey of tested cows were dramatically higher than those of controlled cows respectively. From the bactericidal activity of milk whey in vitro, it could be concluded that in the milk whey the higher specific antibody titer is attained, the higher bactericidal activity is expected.
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