Molecular cloning and immunological characterization of enolase from Streptococcus suis 2

Abstract:

To understand the enolase (eno) gene and its product in Streptococcus suis serotype 2 (S. suis 2), bioinformatics was adopted to analyze the whole genome sequence of the Chinese strain 05ZYH33 of S. suis 2. A highly homologous eno gene was unveiled by the genome-wide mining. A pair of specific primers was designed for the eno, and the target DNA fragment of 1.3 kb was successfully amplified using the genomic template of 05ZYH33. Subsequently, eno gene was inserted into pMD18-T vector, and then subcloned into prokaryotic expression vector pET32a, generating a recombinant expression plasmid pET32a::eno. The resulting plasmid was confirmed by direct DNA sequencing and transformed into E. coli BL21 (DE3) competent cells. Protein expression analysis showed that a 75 kD protein can be observed in 12% SDS-PAGE, indicating that the recombinant 6His-fused ENO protein can be produced in E. coli under the induction of IPTG. Western-blot experiment demonstrated clearly it shares strong specific antigenicity. Moreover, ELISA result suggested that ENO can occur on the surface of 05ZYH33 strain. Together, our data supported that ENO can function as a novel antigen, and may play pivotal roles in the severe infection of S. suis 2.