Outbreak of severe pseudorabies virus infection in pig-offal-fed farmed mink in Liaoning Province, China.

An outbreak of severe pseudorabies virus (PRV) infection in farmed mink occurred in northern China in late 2014, causing significant economic losses in the local fur industry. Here, we report the first case of a PRV outbreak in mink in northeastern China, caused by feeding farmed mink with raw pork or organs contaminated by PRV. Mink infected with virulent PRV exhibited diarrhea, neurologic signs, and higher mortality, which can be misdiagnosed as highly pathogenic mink enteritis virus (MEV), canine distemper virus (CDV), and food poisoning. However, these were excluded as causative agents by PCR or bacteria isolation. The duration of disease was 3-7 days, and the mortality rate was 80-90%. PRV was characterized using indirect immunofluorescence assays (IFA) and electron microscopy (EM). Phylogenetic analysis based on full-length genome sequences and those of individual genes of this novel virus strain showed that it clustered in an independent branch with several other PRV isolates from China.

Construction and immunogenicity of a DNA vaccine coexpressing GP3 and GP5 of genotype-I porcine reproductive and respiratory syndrome virus.

BACKGROUND: The European (EU) genotype of porcine reproductive and respiratory syndrome virus (Genotype-I PRRSV) has recently emerged in China. The coexistence of Genotype-I and -II PRRSV strains could cause seriously affect PRRSV diagnosis and management. Current vaccines are not able to protect against PRRSV infection completely and have inherent drawbacks. Thus, genetically engineered vaccines, including DNA vaccine and live vector engineered vaccines, have been developed. This study aimed to determine the enhanced immune responses of mice inoculated with a DNA vaccine coexpressing GP3 and GP5 of a Genotype-I PRRSV. RESULTS: To evaluate the immunogenicity of GP3 and GP5 proteins from European-type PRRSV, three DNA vaccines, pVAX1-EU-ORF3-ORF5, pVAX1-EU-ORF3 and pVAX1-EU-ORF5, were constructed, which were based on a Genotype-I LV strain (GenBank ID: M96262). BALB/c mice were immunized with the DNA vaccines; delivered in the form of chitosan-DNA nanoparticles. To increase the efficiency of the vaccine, Quil A (Quillaja) was used as an adjuvant. GP3 and GP5-specific antibodies, neutralizing antibodies and cytokines (IL-2, IL-4, IL-10 and IFN gamma) from the immunized mice sera, and other immune parameters, were examined, including T-cell proliferation responses and subgroups of spleen T-lymphocytes. The results showed that ORF3 and ORF5 proteins of Genotype-I PRRSV induced GP3 and GP5-specific antibodies that could neutralize the virus. The levels of Cytokines IL-2, IL-4, IL-10, and IFN-γ of the experimental groups were significantly higher than those of control groups after booster vaccination (P < 0.05). The production of CD3+CD4+ and CD3+CD8+ T lymphocyte was also induced. T lymphocyte proliferation assays showed that the PRRSV LV strain virus could stimulate the proliferation of T lymphocytes in mice in the experimental group. CONCLUSIONS: Using Quil A as adjuvant, Genotype-I PRRSV GP3 and GP5 proteins produced good immunogenicity and reactivity. More importantly, better PRRSV-specific neutralizing antibody titers and cell-mediated immune responses were observed in mice immunized with the DNA vaccine co-expressing GP3 and GP5 proteins than in mice immunized with a DNA vaccine expressing either protein singly. The results of this study demonstrated that co-immunization with GP3 and GP5 produced a better immune response in mice.

Depth and rate dependent mechanical behaviors for articular cartilage: experiments and theoretical predictions.

An optimized digital image correlation (DIC) technique was applied to investigate the depth-dependent mechanical properties of articular cartilage and simultaneously the depth-dependent nonlinear viscoelastic constitutive model of cartilage was proposed and validated. The creep tests were performed with different stress levels and it is found that the initial strain and instantaneous strain increase; however the creep compliance decreases with the increase of compressive stress. The depth-dependent creep strain of cartilage was obtained by analyzing the images acquired using the optimized DIC technique. Moreover the inhomogeneous creep compliance distributions within the tissues were determined at different creep time points. It is noted that both creep strain and creep compliance with different creep times decrease from cartilage surface to deep. The depth-dependent creep compliance increases with creep time and the increasing amplitude of creep compliance decreases along cartilage depth. The depth-dependent and stress rate dependent nonlinear stress and strain curves were obtained for articular cartilage through uniaxial compression tests. It is found that the Young's modulus of cartilage increases obviously along cartilage depth from superficial layer to deep layer and the Young's modulus of different layers for cartilage increases with the increase of stress rate. The Poisson's ratio of cartilage increases along cartilage depth with given compressive strain and the Poisson's ratio of different layers decreases with the increase of compressive strain. The depth-dependent nonlinear viscoelastic constitutive model was proposed and some creep data were applied to determine the parameters of the model. The depth-dependent compressive behaviors of cartilage were predicted by the model and the results show that there are good agreements between the experimental data and predictions.