African Journal of Pig Farming ISSN 2375-0731 Vol. 8 (3), pp. 001-007, March, 2020. © International Scholars Journals

Full Length Research Paper

Phylogenetic and pathogenetic analysis of Streptococcus suis serotype 7 strain HW07 isolated from diseased pig in China

Shujie Wang^1,2, Sen Hu², Jiamin Jin^1,2, Yonggang Liu², Gang Wang ², Yabin Tu², Chenggang Jiang², Xuehui Cai²* and Xiuying Zhang¹*

¹Pharmacology Laboratory, Animal Medical College, Northeast Agriculture University, Harbin 150030, China.

²State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, People’s Republic of China.

Accepted 08 December, 2019

Abstract

A recent isolate of Streptococcus suis serotype 7 (SS7), named HW07, was isolated from brains of pigs suspected with Streptococcus suis (S. suis) infection. The sequence types (ST) of this isolate was determined by Multilocus sequence typing (MLST) method. In order to evaluate pathogenesis of HW07 isolate, zebrafish and pigs were inoculated with HW07 strain by peritoneal cavity and vein. The results demonstrate that the 50% lethal dose (LD₅₀) of HW07 isolate was 1.25 × 10⁵ colony forming units (CFU)/fish and could induce pig disease, the ST number of HW07 isolate is a novel ST-ST335. Molecular and phylogenetic analysis for the recA gene of HW07 isolate showed that it joins to the I group cluster of S. suis strains, the predominant genotype in China.

Key words: Streptococcus suis serotype 7, multilocus sequence typing, the sequence type, phylogenetic analysis.