Insight into the evolution of the histidine triad protein (HTP) family in Streptococcus.

The Histidine Triad Proteins (HTPs), also known as Pht proteins in Streptococcus pneumoniae, constitute a family of surface-exposed proteins that exist in many pathogenic streptococcal species. Although many studies have revealed the importance of HTPs in streptococcal physiology and pathogenicity, little is known about their origin and evolution. In this study, after identifying all htp homologs from 105 streptococcal genomes representing 38 different species/subspecies, we analyzed their domain structures, positions in genome, and most importantly, their evolutionary histories.

Genetic diversity and evolutionary characterization of Chinese porcine reproductive and respiratory syndrome viruses based on NSP2 and ORF5.

To more fully understand the extent of genetic diversity of PRRSV in China, we analyzed the Nsp2 and ORF5 gene sequences of 35 representative PRRSV isolates from 2008 to 2012. Sequence analysis revealed that the Nsp2 and ORF5 genes have undergone genetic variation. Furthermore, the isolate FJLYDX04 contains five insertions at positions 599 to 603 and is the first isolate from China reported to have an insertion in Nsp2.

[Role of Luxs gene on regulation of virulence factors in Salmonella typhimurium].

Objective: To investigate the role of Luxs gene on the regulation of virulence factors in Salmonella typhimurium.

Methods: Luxs gene knock-out strain of Salmonella typhimurium of the line 14028S was constructed. Media with Luxs gene knock-out 14028S or wild type 14028S bacteria were added into the media of cultured human intestinal epithelial cells of the line Caco.

[Construction of RevS gene knock-out mutant of Streptococcus suis serotype 2].

Objective: To construct a gene knock-out mutant of response regulator named RevS in Streptococcus suis serotype 2 virulent strain 05ZYH33, and to investigate the effects of its deletion on the biological characters of this pathogen and the pathogenesis to mice and piglets.

Methods: Recombinant gene knock-out vector consisting of Spc(r) cassette was constructed and flanking was constructed consisting of Spc(r) cassette with flanking homology regions to the RevS genes while the isogenic RevS-deficient mutant was screened by allelic replacement. The effects of RevS deletion on the basic biological characters of 05ZYH33 including growth stability, colonial morphology, haemolysis, Gram staining, growth curve and protein expression were examined in vitro.

[Study on molecular epidemiology of major pathogenic Streptococcus suis serotypes in middle part of Jiangsu province].

Objective: To determine the prevalence of Streptococcus suis and major pathogenic serotypes in middle part of Jiangsu province.

Methods: Tonsillar specimens from 303 slaughtered pigs aged 6 to 8 months were investigated for the presence of Streptococcus suis and major pathogenic serotypes by polymerase chain reaction (PCR) method. Bacteriological examination compared with molecular genetics identification for three Streptococcus suis isolates were also done.

[Homologous analysis of Streptococcus suis srt gene and prokaryotic expression of srtA].

Aim: To elucidate the distribution of srt gene in the genome of S.suis 05ZYH33, prokaryotically express Sortase A and analyze its antigenicity.

Methods: Homologous genes encoding sortase family members were analyzed, and then the srtA gene of S.

[Cloning and prokaryotic expression of truncated muramidase-released protein gene of human Streptococcus suis type 2].

Aim: To clone and express the truncated Habb mrp gene of human Streptococcus suis type 2 (S.suis 2) and detect its activity.

Methods: A pair of primers based on S.

[Detection of virulence-associated factors of Streptococcus suis by multiplex PCR assay].

Objective: To rapidly and sensitively detect the four virulence-associated factors of Streptococcus suis, a multiplex PCR was developed.

Methods: In the process of this reaction, four distinct DNA targets were amplified. One target was based on the serotype 2 (and 1/2) specific cps gene and the others were based on Streptococcus suis mrp, epf (epf*) and sly gene, encoding the MRP, EF(EF*) and Sly proteins of Streptococcus suis.