Staphylococcus aureus is a leading cause of bovine intramammary infections (IMI). Standard antibiotic treatments are not very effective and currently available vaccines lack tangible efficacy. Developing a vaccine formulation for S. aureus mastitis is challenging and selection of target antigens is critical. The gene products of six S. aureus genes that are highly expressed during IMI were selected as antigens for this study. The vaccine contained six recombinant proteins formulated with Emulsigen®-D, a CpG oligodeoxynucleotide and indolicidin. Nine cows in mid-lactation received the vaccine while ten received saline (placebo). Two immunizations were performed 10 weeks apart. All the antigens induced an immune response. A balanced immune response (IgG2/IgG1 ratio of 1) was observed for antigen SACOL0442 while a predominant Th2 response was observed for the other antigens (IgG2/IgG1 ratio <1). Immunizations induced CD4+ cell proliferation in response to SACOL0442, SACOL0029, SACOL0720 and SACOL1912 while a CD8+ cell proliferation was induced by SACOL0720. Four weeks after the second immunization, three quarters per animal were experimentally infused with ∼60 CFU of S. aureus. Although no difference in S. aureus counts was observed between the two groups after this robust infectious challenge, a sustained reduction in milk somatic cells counts (SCC) was observed in vaccinated cows. A correlation between SCC and S. aureus counts in milk was also observed. Altogether, this indicates that the collective immune responses induced by the antigens certainly contribute to the observed benefits of the whole vaccine. More work is needed to understand how different antigens stimulate a different response using the same adjuvant.

金黄色葡萄球菌是牛乳房内感染 (IMI) 的主要原因。标准的抗生素治疗不是很有效，目前可用的疫苗缺乏明显的功效。开发金黄色葡萄球菌乳腺炎疫苗制剂具有挑战性，目标抗原的选择至关重要。六种金黄色葡萄球菌的基因产物选择在 IMI 期间高度表达的基因作为本研究的抗原。该疫苗含有六种重组蛋白，由 Emulsigen®-D、CpG 寡脱氧核苷酸和 indolicidin 配制而成。九头处于泌乳中期的奶牛接种了疫苗，而十头则接种了生理盐水（安慰剂）。间隔10周进行两次免疫。所有抗原均诱导免疫反应。对抗原 SACOL0442 观察到平衡的免疫反应（IgG2/IgG1 比率为 1），而对其他抗原（IgG2/IgG1 比率 <1）观察到主要的 Th2 反应。免疫接种响应 SACOL0442、SACOL0029、SACOL0720 和 SACOL1912 诱导 CD4+ 细胞增殖，而 SACOL0720 诱导 CD8+ 细胞增殖。第二次免疫后 4 周，每只动物的四分之三被实验性地注入了约 60 CFU 的金黄色葡萄球菌。尽管在这种强烈的感染性攻击后，两组之间没有观察到金黄色葡萄球菌计数的差异，但在接种疫苗的奶牛中观察到牛奶体细胞计数 (SCC) 持续减少。还观察到牛奶中SCC 和金黄色葡萄球菌计数之间的相关性。总之，这表明抗原诱导的集体免疫反应肯定有助于观察到的整个疫苗的益处。需要做更多的工作来了解不同的抗原如何使用相同的佐剂刺激不同的反应。