Immunogenicity of recombinant M protein of Streptococcus equi subsp. equi co administered with a molecular adjuvant

ABSTRACT The strangles is an infectious disease that affects horses from all ages and causes important economic losses in the equine-related business. The aim of this work was to evaluate the immunogenicity of the recombinant M protein from Streptococcus equi (rSeM) co-administered with the recombinant heat-labile enterotoxin B subunit from Escherichia coli (rLTB) in mice and horses. A total of 72 female Balb-c mice were divided into eight groups and 18 horses were divided into six groups. The animals were inoculated by intramuscular (IM) or intranasal (IN) routes with different treatments of rSeM, rLTB and/or Al(OH)3. The results obtained in both species, independent of administration routes, demonstrated that rSeM + rLTB had higher levels of specific serum immunoglobulins, however, in mucosal immunity the increase was not identified. Thus, the use of rSeM as vaccine antigen and rLTB as adjuvant can be a potential tool in the control of equine strangles.摘要 马腺疫（Strangles）是一种可感染各年龄段马匹的传染性疾病，会给马相关产业造成重大经济损失。本研究旨在评估马链球菌（Streptococcus equi）重组M蛋白（recombinant M protein from Streptococcus equi，简称rSeM）与大肠杆菌（Escherichia coli）不耐热肠毒素B亚基（recombinant heat-labile enterotoxin B subunit from Escherichia coli，简称rLTB）联合给药后，在小鼠和马匹体内的免疫原性。实验共纳入72只雌性BALB/c小鼠，分为8组；18匹马匹被划分为6组。受试动物通过肌内（intramuscular，IM）或鼻内（intranasal，IN）途径接种不同组合的rSeM、rLTB及氢氧化铝（Al(OH)3）佐剂。两种受试动物的实验结果均显示，无论接种途径如何，rSeM与rLTB联合给药组的血清特异性免疫球蛋白水平均显著更高，但未观察到黏膜免疫水平的明显提升。综上，以rSeM作为疫苗抗原、rLTB作为佐剂，有望成为控制马腺疫的潜在防控工具。