Streptococcus agalactiae irradiated vaccine candidate for subclinical mastitis prevention in ruminants.

Abstract

Subclinical mastitis (SCM) is a disease that often infects dairy cow, which then decline milk production. Streptococcus agalactiae is well known as a dominant causative agent of SCM. An experiment to obtain gamma irradiated candidates vaccine of S. agalactiae for the prevention of subclinical mastitis in ruminants have been conducted. S. agalactiae bacteria selected for the irradiated vaccine material was isolated from dairy cows of subclinically mastitis from dairy farm in Bogor and Garut area. The S. agalactiae used in this experiment was group B (GBS) type, which is uncapsulated and has haemaglutynine (Hn+) property. Based on dose irradiation orientation, 17 Gy dose was found to weaken the GBS bacteria to have 50% lethal dose (LD50), which therefore, utilized to manufacture live vaccine. Irradiated GBS surface protein was characterized by SDS-PAGE and resulted to find more than 75 kDa of the protein’s molecular weight, where minimun of antigenically substance is 10 kDa. Infecting of the irradiated GBS using mice resulted in lack pathogenic properties of the bacteria, which is histophatology drawn that the mammary gland alveolly of mice grouped vaccinated with irradiated GBS and vaccinated then challenge, were remain producing milk, and significantly not different as compare to control animal. GBS vaccine irradiation did not cause inflammation of the mammary glands of mice tested, evidences showed that number of udder interstitial inflammatory cells around alveolly and gland epithelial cells in vaccinated mice groups were not significantly different as compare to the control group. Most interstitial inflammatory cells in challenged groups are found in mice that were challenged with virulent GBS and significantly different to be found more as compare to vaccine and control groups. Enzyme Linked Immunosorbent Assay (ELISA) to Ig-G serum showed levels of higher immune response in mice vaccinated group compare to control group. The overall experiment confirmed that attenuated GBS using gamma ray irradiation capable to induce immune response. This evidences were confirmed by an observation result in the application of GBS irradiated vaccine at Etawah dairy-goat, where immune responses are induced in those dairy-goats, and also were showed by the evidences found of higher concentration of Ig-G serum by ELISA in the vaccinated group than the control group. Milk production of vaccinated goat had no effect by vaccination. In summarize, irradiated SGB vaccine does not affect milk yield.