Effects of srtA variation on phagocytosis resistance and immune response of Streptococcus equi

文献类型： 外文期刊

第一作者： Zhang, Huan

作者： Zhang, Huan;Zhou, Tingting;Wang, Hao;Zhang, Baojiang;Su, Yan;Su, Lining

作者机构：

关键词： srtA; Mutation; Streptococcus equi; Antiphagocytic activity; Immune function

期刊名称：INFECTION GENETICS AND EVOLUTION （ 影响因子：2.773； 五年影响因子：2.72 ）

ISSN： 1567-1348

年卷期： 2021 年 89 卷

页码：

收录情况： SCI

摘要： Strangles, which is caused by Streptococcus equi subspecies equi (S. equi), is one of the most prevalent equine infectious diseases with worldwide distribution and leads to serious economic loss in the horse industry. Sortase A (srtA) is a transpeptidase that anchors multiple virulence-associated surface proteins to the cell surface of S. equi. srtA plays a major role in S. equi infection and colonization of the host cell. In this study, we aimed to investigate the effects of srtA mutation on the phagocytic activity and immunogenicity of S. equi. The pointmutated recombinant sortases, including srtA-HT1112 (I88V), srtA-5012 (R147G), and srtA-ZZM17 (control), were expressed, purified, and used to immunize the mouse models. Phagocytic activity was assessed using equine polymorphonuclear cells, whereas opsonophagocytic function and adherence inhibition were measured using the antiserum of these mutants. Mouse serum antibody, bacterial load, and weight gain were also measured. The srtA-HT1112 (I88V) mutant showed significantly enhanced antiphagocytic capability, and its antiserum exhibited increased adherence inhibition activity. In addition, the srtA-HT1112 (I88V) mutant presented the highest lung bacterial load and lowest protection rate (50%) after the challenge with S. equi ZZM17. The srtA5012 (R147G) mutant exhibited a high IgG2a level and protection rate (62.5%?75%) and the lowest lung bacterial load. These results indicate that the I88V mutation is associated with a high antiphagocytic activity, whereas R147G mutation is associated with the decreased lung bacterial load. Our findings may be useful for the evaluation and development of vaccines.

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