在猪链球菌2型江苏分离株中发现新的orf2毒力相关基因

摘要： 根据文献报道的猪链球菌（Streptococcus suis ）2型一种新的毒力基因相关序列,设计和合成一对引物,以猪链球菌2型江苏分离株HA9801的DNA为模板,扩增推导的毒力基因的完整阅读框,并定向克隆到质粒载体pET-32a（+）中,经测序表明,与国外推测的毒力基因完全同源。此外,以猪链球菌和其它链球菌猪源的国内分离株的基因组DNA为模板,通过PCR技术,检测这一推测毒力基因的出现率。该基因在猪链球菌2型的阳性率为7/8,在其它猪源链球菌的阳性率为9/23,在猪源链球菌的总检出率为51.6%（16/31）。

Detection of a New Virulence Associated Gene in Streptococcus suis Type 2 Jiangsu Isolate

Abstract: Streptococcus suis type 2 is an important pathogen for pig and human. It has different virulence factors including muramidase-released protein(MRP), extracellular factor(EF), suilysin and capsular polysaccharide. Smith H E et al(2001) had successfully detected a new virulence associated sequence orf2 by using the method in vivo complementation. It was interesting to investigate the new orf2 in swine streptococcal strains isolated in China. The results showed that the new orf2 was detected from genomic DNA of Streptococcus suis type 2 Jiangsu isolate HA9801 by polymerase chain reaction(PCR) technique and the PCR product from isolate HA9801 was choned into plasmid vector pET-32a(+) via restriction endonuclease Bam HⅠand Hind Ⅲ. The recombinant fragment was verified by restriction endonuclease analysis and sequenced. The nucleotide sequence was 100% homological to that of the new hypothetical virulence assolated sequence orf2 reported by Smith H E. By the same method, this orf2 was also detected from genomic DNA of Streptococcus suis type 2 strains and other streptococcal isolates from swine in China. 7/8 of Streptococcus suis type 2 isolates and 9/23 of other streptococcal isolates from pigs were positive. The positive ratio of the orf2 in all isolates including Lancefield group A, B, C, D, R and other serotypes of Streptococcus was 51.6%(16/31). It suggested that the new orf2 distributed widely among streptococcal strains of pigs from different areas in China. The pathogenicity of the orf2 would be further studied