Distributions of pathogenic capsular types and in vitro antimicrobial susceptibility of different serotypes of Streptococcus suis isolated from clinically healthy sows from 10 provinces in China / 中华流行病学杂志

Objective To determine the distributions of major pathogenic capsular types and in vitro antimicrobial susceptibility of different serotypes of Streptococcus suis isolated from clinically healthy sows in China. Methods Tonsil specimens of clinically healthy sows from 10 different provinces in China were collected, a total of 421 S.suis were isolated. Capsular types of S.suis were decided using the sera agglutination reaction. Antimicrobial susceptibility testing was performed using a broth microdilution method and the differences between serotypes were decided statistically. Results The prevalent capsular types of S.suis isolated from clinically healthy sows were 9(26.6% ), 3 (23.5%) and 7(15.7% ) types, respectively. 7.4% of isolates were confirmed to be S.suis type 2. Overall, differences in antimicrobial susceptibility among serotypes of S. suis were found. By comparison, lower resistance was observed for S.suis type 2 from clinically healthy sows. Conclusion The prevalence of pathogenic S.suis serotypes from clinically healthy sows again indicates S.suis is a conditional pathogenic bacterium. Differential prevention and treatment regimes should be considered according to antimicrobial susceptibility of different serotypes of S.suis.

Research of real-time fluorescent PCR in the rapid differential detection of H5, H9, H7 subtype avian influenza inactivated vaccines / 生物工程学报

Specific primers and TaqMan MGB probes were designed with Primer Express 2.0 software according to the conserved region of the H5, H9, H7 subtype AIV hemagglutinin gene to make research of real-time fluorescent one-step PCR in the differential detection of H5, H9, H7 subtype avian influenza inactivated vaccines. The result showed that the method was specific and reproducible. No cross-reaction was discovered with other avian disease vaccines. Real-time fluorescent PCR provided a specific, sensitive, rapid and convenient method for the subtype identification of avian influenza inactivated vaccines.

Cloning and expression of interferon-alpha/gamma from a domestic porcine breed and its effect on classical swine fever virus.

To further evaluate the clinical impact of recombinant PoIFN-alpha/gamma, PoIFN-alpha/gamma genes from a Chinese domestic big-white porcine breed were cloned using PCR, and expressed in a high-level prokaryotic system. The antiviral activities of rPoIFN-alpha/gamma on vesicular stomatitis virus (VSV), porcine reproductive and respiratory syndrome virus (PRRSV), and classical swine fever virus (CSFV) were investigated in different cell lines. The cloned PoIFN-alpha gene encodes a protein of 166 amino acids and has been named PoIFN-alphac. In a comparison of PoIFN-alphac with reported PoIFN-alphaI genes, eight amino acid substitutions at positions 43 (F to L), 78 (N to D), 86 (Y to C), 104 (A to V), 118 (R to L), 128 (T to P), 151 (S to V), and 156 (R to T) were observed, and resulted in no potential N-glycosylation site in the deduced PoIFN-alpha amino acid sequences. In contrast to PoIFN-alphac, one nucleotide substitution was found at position 462 (A to G), hence 0.1% synonymity is specific for the PoIFN-gamma gene. Both PoIFN-alphac and PoIFN-gamma genes were inserted into a prokaryotic vector pQE30, and expressed in E. coli M15 (pREP4) or SC11103 (pREP4) with the N-terminal six consecutive histidine residues, respectively. rPoIFN-alphac and rPoIFN-gamma proteins were detected by SDS-PAGE and Western blotting analysis at 20.7 and 18.0 kDa, respectively. In addition, the rPoIFN-alphac and rPoIFN-gamma protein were purified using Ni-NTA metal-affinity chromatography, and their anti-VSV, anti-PRRSV, and anti-CSFV activities were surveyed in homologous and heterologous cell lines. The results suggested that rPoIFN-alpha and rPoIFN-gamma could inhibit classical swine fever virus and other important viral pathogens in different cell lines.

RESEARCH ON THE TESTING OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS BY NESTRT-PCR / 微生物学通报

Three primer were designed based on the consevered area of the genetic of the ATCC VR-2332 strain and LV strain. And the nest RT-PCR of testing porcine reproductive and respiratory syndrome virus were developed. The nest RT-PCR against ATCC VR-2332 strain, LV strain and B13 strain were done by this method.The DNA fragment were obtained specially from the three strains isolated from different region. The size were 430bp (430bp) , 410bp (413bp) and 410 bp (413bp) separately. But the DNA fragment were not obtained from HCV, PPV and PRV. Its sensitivity was 10-2 TCID50. It's sensitivity increased 10000 times than one step RT-PCR. It should make the method of testing porcine reproductive and respiratory syndrome virus more sensitive, fast and accurate.