Roy David, Auger Jean-Philippe, Segura Mariela, Fittipaldi Nahuel, Takamatsu Daisuke, Okura Masatoshi, Gottschalk Marcelo
Groupe de recherche sur les maladies infectieuses du porc et Centre de recherche en infectiologie porcine et avicole, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Quebec J2S 2M2 (Roy, Auger, Segura, Gottschalk); Public Health Ontario, Resources Road, Toronto, Ontario M9P 3T1 (Fittipaldi); Bacterial and Parasitic Disease Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Kannondai, Tsukuba, Ibaraki, 305-0856, Japan (Takamatsu, Okura); The United Graduate School of Veterinary Sciences, Gifu University, Yanagido, Gifu 501-1193, Japan (Takamatsu).
Can J Vet Res. 2015 Apr;79(2):141-6.
Streptococcus suis is an important swine pathogen and a zoonotic agent causing meningitis and septicemia. Although serotype 2 is the most virulent type, serotype 14 is emerging, and understanding of its pathogenesis is limited. To study the role of the capsular polysaccharide (CPS) of serotype 14 as a virulence factor, we constructed knockout mutants devoid of either cps14B, a highly conserved regulatory gene, or neu14C, a gene coding for uridine diphospho-N-acetylglucosamine 2-epimerase, which is involved in sialic acid synthesis. The mutants showed total loss of the CPS with coagglutination assays and electron microscopy. Phagocytosis assays showed high susceptibility of mutant Δcps14B. An in vivo murine model was used to demonstrate attenuated virulence of this non-encapsulated mutant. Despite the difference in the CPS composition of different serotypes, this study has demonstrated for the first time that the CPS of a serotype other than 2 is also an important antiphagocytic factor and a critical virulence factor.
猪链球菌是一种重要的猪病原体，也是一种可导致脑膜炎和败血症的人畜共患病原体。虽然2型是最具毒力的血清型，但14型正在出现，对其发病机制的了解有限。为了研究14型荚膜多糖（CPS）作为一种毒力因子的作用，我们构建了缺失高度保守的调控基因cps14B或编码参与唾液酸合成的尿苷二磷酸-N-乙酰葡糖胺2-差向异构酶的基因neu14C的基因敲除突变体。通过协同凝集试验和电子显微镜观察，突变体显示出CPS完全缺失。吞噬试验表明突变体Δcps14B具有高易感性。使用体内小鼠模型来证明这种无荚膜突变体的毒力减弱。尽管不同血清型的CPS组成存在差异，但本研究首次证明除2型以外的血清型的CPS也是一种重要的抗吞噬因子和关键毒力因子。
