Evaluate the efficacy of a multivalent inactivated vaccine against bovine mastitis

• Main Authors: Shen, You-Sheng, 沈宥陞
• Other Authors: Chu, Chun-Yen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/48048772860063875057

碩士 === 國立屏東科技大學 === 動物疫苗科技研究所 === 104 === Bovine mastitis is often caused by a variety of pathogens, in which Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Streptococcus agalactiae are the major pathogens. Infected cows may have clinical signs, including swelling, heat and pain, fever, depression, decreased milk production and increased number of milk somatic cells. E. coli J5 is a mutant strain of gram-negative bacteria with the completely exposed core antigen that can be easily contacted by immune cells to produce antigen-specific antibodies. S. aureus T8 is the highest ratio of isolation from cows with mastitis. In addition, S. aureus Smith compact is a mutant strain that can elicit antibodies which are able to block the attachment of S. aureus to mammary epithelial cells. Several studies have demonstrated that clumping factor A (ClfA) is a important virulence factor bond to the fibrin of host epithelial cells. In this study, we combined three strains of bacteria and one recombinant ClfA as the multivalent vaccine. The results showed that the serum antibody titer of T8/SC/J5 + rClfA-SC9 and T8/SC/J5 were significantly higher than the control (p <0.05) during 4 to 8 weeks in mouse model. The T cell proliferation index of immunized groups were also significantly higher than the control (p <0.05). In addition, the survival rate of rClfA-SC9 was higher than other groups (p <0.05) after mice challenged by E.coli No. 2 and S. aureus A476. In bovine efficacy test, serum antibody titer of immunized groups were significantly higher than the control (p <0.05) in 4 week. But the whey antibody titer and the stimulation index of PBMC were no significantly between immunized and control groups. However, the cytokines expression of immunized groups had phenomenon of upregulation. Based on the results, rClfA-SC9 still need to furher evaluate whether the potential development of mastitis vaccine.