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Porcine reproductive and respiratory syndrome virus (PRRSV), which leads to tremendous economic losses worldwide, is currently one of the most threatening viruses for the swine industry. However, PRRSV outbreaks in West China are rarely reported, even though the virus has remained active for a long time across the country., Porcine reproductive and respiratory syndrome virus (PRRSV), which leads to tremendous economic losses worldwide, is currently one of the most threatening viruses for the swine industry. However, PRRSV outbreaks in West China are rarely reported, even though the virus has remained active for a long time across the country. In this study, we report an outbreak of the highly pathogenic PRRSV strain QTX, isolated from a pig farm located in Ningxia, a province in West China.

A moderate heat-resistant lipase gene from Bacillus subtilis FS1403 was cloned. Sequence analysis revealed that the lipase gene encodes a 212-amino-acid protein containing the conserved motif Ala-X-Ser-X-Gly that is present in other Bacillus lipases. Phylogenetic analysis suggested that the B. subtilis FS1403 lipase gene belongs to family I.4 of bacterial lipase genes. The lipase gene was inserted in pET-28a(+) and expressed in Escherichia coli BL21. SDS-PAGE analysis revealed that the recombinant lipase had a molecular weight of approximately 23 kDa, which corresponded to the predicted size (22.8 kDa) of the deduced protein. The lipase activity was the highest at 50°C and at pH 8.0. The enzyme retained over 70% of the maximal activity at temperatures of 40–60°C and pH 6.0–11.0.

An open reading frame of 1100 bp in the partially sequenced genome sequence of alkaliphilic Bacillus pseudofirmus OF4 was identified as a putative alanine racemase gene (dadX(OF4)), which was cloned and expressed in Escherichia coli BL21 (DE3). The encoded protein DadX(OF4) was purified to homogeneity by His(6)-tag affinity column, gel filtration and ion-exchange chromatography. The amino acid sequence has highest identity with the known alanine racemase from Oceanobacillus iheyensis HTE831 (48%). The protein was a dimeric, endogenous PLP-dependent enzyme, which was demonstrated by absorption spectra and enzyme activity with or without PLP. The racemization temperature optimum was 40 degrees C and the optimal pH was 10.5. The kinetic parameters K(m) and V(max) at 40 degrees C of alanine racemase, determined by HPLC analysis, were 41.79 mM, 10,500 units/mg for L-alanine and 14.91 mM, 3708 units/mg for D-alanine, respectively.

An immunochromatographic strip (GICA strip) was developed for the simple and rapid detection of antibodies against classical swine fever virus (CSFV). In the GICA strip, the expressed protein of E2 was labeled with colloidal gold and was used as the detector, and the staphylococcal protein A (SPA) and swine antibody against CSFV blotted on the nitrocellulose membrane were used for the test and control lines, respectively. Conjugation of E2 protein with colloidal gold was optimal at 5.25 μg of protein per mL of colloidal gold. The optimum concentration of the E2 protein applied at the test line was 1.5 mg/mL. The GICA strip was specific for antibodies against CSFV, produced negative results with sera from noninfected pigs or other animals, and was as sensitive or nearly as sensitive as ELISA and HI. According to the comparison of GICA strips with IDEXX ELISA kits, the coincidence rate was 93.26 %. The strips produced results within 5–15 min and can be stored at 4 °C for 3 years or 37 °C 1 year. The strip can be useful for both country veterinarians and field epidemiologists.