Tropical study on Clinical and Host Cell Responses of Acute Phase Proteins, Pro-Inflammatory Cytokines and Antibodies’ in Lactating Dairy Cows Vaccinated and Challenged with S. aureus

Abstract

In the tropical region of Malaysia (the study area), the climate has a mean annual temperature of 25.4°C with the hottest months of the year being April, May and June. On an average, December is 83.0% the most humid (MMD, 2017). It was confirmed by Cunha et al. (2008); that dairy cows raised in tropical conditions had less milk production as the somatic cell count (SCC) increased in mastitis cases. In humid tropics, Insua et al. (2008) also reported mastitis prevalence of about 42.0 %. The reduction in milk production due to cases of clinical mastitis is the component with the largest weight (42.2%) in the total economic impact of mastitis due to the large percentage of cows with SCCs. Therefore, the intensification of dairying, especially under tropical conditions, presents disease problems with mastitis as an important occurrence. And dairy farmers in the study area have reported cases of reduced dairy production and evidence of mastitis in dairy cows. This paper aims to provide an understanding of the effect developed killed vaccine on IgG, IgM, IgA, interleukin-10, interleukin-12, haptoglobin and serum amyloid A concentration on vaccinated and challenged dairy cows raised under tropic condition. Six lactating dairy cows were grouped into 3 treatment groups. Group A and B were inoculated intramuscularly with 2ml of normal saline while Group C received 108 CFU/ml of the killed bacteria followed by a booster. The cows in group B and C were inoculated with 2ml of 106 CFU live S. aureus bacterin in each mammary gland quarter while treatment group A was inoculated with 2ml of normal saline a week post booster. Blood samples were periodically collected. There was significant difference in the rectal temperatures, heart, and respiratory rates among the treatment groups. Results of the current study however, revealed that antibodies titres of immunoglobulin M, G and A were significantly (p<0.05) elevated throughout the post-primary vaccination, post-booster vaccination and post challenge phases. In addition, there were significant differences (p<0.05) in the interleukin-10, interleukin-12, haptoglobin and serum amyloid A concentration at different phases between treatment groups. In conclusion, this study revealed that the prototype killed S. aureus vaccine could induce significant clinical and humoral immune responses needed for improving dairy production in tropical climates such as that of Malaysia. This was deduced from the reaction of pro-inflammatory cytokines and acute phase proteins biomarkers.