Feeder cells can promote cell proliferation and help overcome the developmental arrest of early embryos by producing growth factors. The objective of this study was to evaluate the effects of feeder cells on the development of all single porcine parthenogenetic embryos in vitro. Firstly, we showed that the cleavage and blastocyst formation rate of all single procine parthenogenetic embryos co-cultured with feeder cells increased in contrast to those cultured without feeder cells (p<0.05). However, no statistically significant differences were observed between the blastocyst formation rate in the embryos co-cultured with 3 different kinds feeder cells namely oviduct epithelial feeder cells, granulose feeder cells and porcine fetal fibroblast feeder cells (p>0.05). Secondly, highly significant differences were observed between the cleavage and blastocyst formation rate (p<0.05) when the embryos were co-cultured with oviduct epithelial feeder cells in different volume drops ranging from 3 to 20 μL and the cleavage rate were the highest when cultured in 5 μL drops. Thirdly, the tempospacial pattern of the development of single embryos co-cultured with oviduct epithelial feeder cells was consistent with that of traditional multi-embryo culture, indicating that the co-culturing does not affect the developmental competence of the porcine parthenogenetic embryos. Finally, highly significant differences were observed between the cleavage and blastocyst formation rate with and without zona pellucida in vitro (p<0.05). In this study, a new adaption of in vitro co-culture of single porcine parthenogenetic embryos using feeder cells has been successfully established and this will facilitate further investigations to discover the mechanistic mode of developmental arrest of porcine embryos.

In this study, we investigate the mechanical behavior of each skin layer, in terms of the nominal stress-strain curve by uniaxial tensile tests using specimens of porcine skin in two forms: dermis containing epidermis, and all three layers. All tests were performed under cyclic loading at the constant strain rate of 10–3 s–1 at ambient temperature. To measure the precise initial cross-sectional areas of each layer, the thickness of each skin layer was quantified by counting the number of pixels on the photo-image using image-processing software. In the tensile test, force-strain curves of the total skin and dermis with epidermis were obtained. Subsequently, a rule of mixtures was applied to determine the nonlinear mechanical properties of the hypodermis layer. In conclusion, we could define the uniaxial tensile behavior of the hypodermis, and additionally predict the weight effect of the dermis and hypodermis layers in the tensile test.

Uniaxial tensile tests were performed on porcine skin to investigate the tensile stress-strain constitutive characteristic at quasistatic deformations using uniaxial tensile tests. Experimental results were then used to determine the parameters of the various constitutive model types for rubber, including the Mooney-Rivlin, Yeoh, Ogden, and others. The Prony series viscoelastic model was also calibrated based on the stress relaxation test. To investigate the calibrated constitutive equations (visco-hyperelastic), the falling impact test was conducted. From the viewpoint of the maximum impact load, the error was approximately 15.87%. Overall, the Ogden model predicted the experimental measurements most reasonably. The calibrated constitutive model is expected to be of practical use in describing the mechanical properties of porcine skin.

An eukaryotic expression system of Congjiang pigs IFN-λ1 was constructed to obtain its expression in CHO-K1 cells and the inhibition effect of Congjiang pig IFN-λ1 on PRRSV proliferation was verified. The eukaryotic expression plasmid pEGFP-PoIFN-λ1 was constructed from the pig IFN-λ1 gene fragment and transfected into CHO-K1 cells. Expression was detected by fluorescence microscopy and Western blotting. The influence on the proliferation of PRRSV was assessed. The results of the study showed that the recombinant plasmid pEGFP-PoIFN-λ1 was constructed correctly. After transfection, green fluorescent signal was detected in CHO-K1 cells by fluorescence microscopy. Western blot analysis revealed that in cells at different time periods after transfection, porcine IFN-λ1 was expressed, with the highest expression observed 36 h after transfection. The antiviral activity of the supernatant after 36 h of transfection was determined by the micro cytopathic inhibition method, and the biological activity was 2.1×103 U/mL. Quantitative PCR was used to detect the proliferation of PRRSV, and the results showed that Congjiang pigs IFN-λ1 significantly inhibited the mRNA expression of PRRSV and viral proliferation in a dose- and time-dependent manner. This study established a Congjiang pig IFN-λ1 eukaryotic expression system, and the quantitative PCR method showed that it has a significant inhibitory effect on the proliferation of PRRSV, which lays a foundation for the future production of antiviral drugs and clinical application.

In this study, a SYBR Green-based real-time quantitative polymerase chain reaction (qPCR) assay was developed for rapid detection of porcine parvovirus (PPV) 6. Primer pairs targeting the conserved regions of PPV6 Capsid gene were designed. Sensitivity analyses revealed the lowest detection limit of the SYBR Green-based real-time PCR assay to be 47.8 copies/μL, which indicated it was 1000 times higher than that found in the conventional PCR investigations. This assay was specific and showed no cross-species amplification with other six porcine viruses. The assay demonstrated high repeatability and reproducibility; the intra- and inter-assay coefficients of variation were 0.79% and 0.42%, respectively. The positive detection rates of 180 clinical samples with SYBR Green-based real-time PCR and conventional PCR were 12.22% (22/180) and 4.44% (8/180), respectively. Our method is sensitive, specific, and reproducible. The use of SYBR Green-based real-time PCR may be suitable for the clinical detection and epidemiological investigation of PPV6.

To explore the role of Toll-like receptors (TLRs) and interferon (IFN) in the innate immunity against porcine epidemic diarrhea virus (PEDV), we detected the expression of TLR genes in PEDV-infected IPEC-J2 cells by real-time PCR. We also detected the level of interferon α (IFN-α) and interferon γ (IFN-γ) by enzyme-linked immunosorbent assay (ELISA). Results showed that IPEC-J2 cells exhibited a clear pathological change after PEDV infection at 24 h. In addition, TLR7, TLR9 and TLR10 expressions were significantly upregulated in PEDV-infected IPEC-J2 cells at 24 h. Interestingly, the expression patterns of TLR2 and TLR4 were consistent at different stages of PEDV infection. The expression level of TLR3 decreased significantly with the increase of infection time, but the expression levels of TLR5 and TLR8 genes at 6 h and 12 h were significantly lower than those in the control group (p<0.01). There were significant correlations among the expression levels of TLR genes (p<0.05). Cytokine detection showed that the secretion level of IFN-α in the PEDV-infected group was significantly higher than that in the control group (p<0.01), and IFN-γ at 6 h and 12 h after PEDV infection was significantly higher than that in control group (p<0.01). Therefore, our results suggest that PEDV infection can induce innate immune responses in intestinal porcine jejunum epithelial cells, leading to changes in the expression of Toll-like receptors, and can regulate the resistance to virus infection by affecting the release levels of downstream cytokines.

The pathogenesis of porcine contagious pleuropneumonia is poorly understood. In the present study, a mouse model of intranasal infection by Actinobacillus pleuropneumoniae (App) was used to examine lung inflammation. The pathogical results of lung tissues showed that App-infected mice showed dyspnea and anorexia, with severe damage by acute hemorrhage, and infiltration of eosinophils and lymphocytes, as well as increased expression of caspase-1 p20, interleukin (IL)-1β, IL-6, IL-8, IL-18 and tumor necrosis factor (TNF)-α. Caspase-1 inhibitors reduced both lung tissue damage and the expression of caspase-1 p20, IL-1β, IL-6, IL-8, TNF-α and IL-18 in infected mice. These findings suggest that the caspase-1 dependent pyroptosis involved in the pathogenesis of the mouse pleuropneumonia caused by App and the inhibition of caspase-1 reduced the lung injury of this pleuropneumonia

Coronaviruses present a considerable concern for humans and animals. The current world- wide pandemic of SARS-CoV-2 virus showed many gaps in understanding of coronaviruses spread and transmission. Because of lack of effective vaccine against SARS-CoV-2 the only preventive measures are represented by wearing protective masks and gloves thus limiting potential risk of contact with the airborne virus. Inversely, the limited time of protective function of the masks presents another drawback of their use. Therefore, the application of disinfection agent dispersed on the surface of protective masks may enhance their effectivity and safety of their application. The aim of the study was to examine the virucidal efficacy of low-concentra- ted sodium hypochlorite dispersed using ultrasonic humidifier on the surface of surgery masks. The study was conducted using SARS-CoV-2 surrogate virus, namely porcine epidemic diarrhea virus (PEDV) representing a model with similar biophysical properties and genomic structure to human coronaviruses. Five different concentrations of the disinfectant with different content of sodium hypochlorite were selected for the study. A final concentration of 0.228 g/L sodium hypochlorite effectively inactivated the PED virus and may support the biosafety of masks usage.