Background: Japanese encephalitis (JE) caused by Japanese encephalitis virus (JEV) accounts for acute illness and death. However, few studies have been conducted to unveil the potential pathogenesis mechanism of JEV. Dendritic cells (DCs) are the most prominent antigen-presenting cells (APCs) which induce dual humoral and cellular responses. Thus, the investigation of the interaction between JEV and DCs may be helpful for resolving the mechanism of viral escape from immune surveillance and JE pathogenesis.Results: We examined the alterations of phenotype and function of DCs including bone marrow-derived DCs (bmDCs)in vitroand spleen-derived DCs (spDCs)in vivodue to JEV P3 wild strain infection. Our results showed that JEV P3 infected DCsin vitroandin vivo. The viral infection inhibited the expression of cell maturation surface markers (CD40, CD80 and CD83) and MHC, and impaired the ability of P3-infected DCs for activating allogeneic naive T cells. In addition, P3 infection suppressed the expression of interferon (IFN)-α and tumor necrosis factor (TNF)-α but enhanced the production of chemokine (C-C motif) ligand 2 (CCL2) and interleukin (IL)-10 of DCs. The infected DCs expanded the population of CD4+ Foxp3+ regulatory T cell (Treg).Conclusion: JEV P3 infection of DCs impaired cell maturation and T cell activation, modulated cytokine productions and expanded regulatory T cells, suggesting a possible mechanism of JE development.

Background: Japanese encephalitis (JE) is a serious zoonosis caused by the Japanese encephalitis virus (JEV) which is a mosquito-borne pathogen of the family Flavivirus. However, the application of several developed laboratory methods for the detection of JEV antigens or antibodies are limited by their requirements of laboratory operations, skilled technicians and special facilities. Results: To develop a method for detecting JEV antigen in swine, human, mosquito and other clinical specimens specifically, conveniently and effectively, an antigen capture enzyme-linked immunosorbent assay (ELISA) was established in this study. Sensitivity, specificity, repeatability and stability of the developed method were evaluated, and 60 clinical samples were tested in this study. The results demonstrated that the antigen capture ELISA was capable in detecting JEV antigen with high sensitivity and specificity compared with conventional methods. 14 samples showed the positive result with coincidence rate of 70%, and 46 displayed negative result with coincidence rate of 100% as compared to that of reverse transcription-polymerase chain reaction (RT-PCR). Conclusions: The developed ELISA assay provides a convenient and specific method for the large-scale determination of JEV antigen in infected swine, human and mosquito samples with high sensitivity and specificity.

Rapid transmission and high mortality of Ebola virus disease (EVD) highlight a urgent need of large scale, convenient and effective measure for Ebola virus screening. Application of monoclonal antibodies (mAbs) are crucial for establishment of an enzyme-linked immunosorbent assay (ELISA) with high sensitivity and specificity. The traditional cell fusion technique was used to generate a panel of hybridomas. Two mAbs were characterized by SDS-PAGE, Western blot, Indirect immunofluorescence assay (IFA). A sandwich ELISA was established using the two mAbs. The detection capability of the ELISA was evaluated. In the current study, we produced two murine-derived mAbs (designated as 6E3 and 3F21) towards Zaire Ebola virus glycoprotein (GP), the major viral transmembrane spike protein associated with viral attachment. It was shown that 6E3 and 3F21 recognized GP1 and GP2 subunits of the GP respectively. Furthermore, 6E3 and 3F21 bound to corresponding epitopes on GP without reciprocal topographical interpretation. Subsequently, a sandwich ELISA based on the two mAbs were established and evaluated. The detection limit was 3.6 ng/ml, with a linear range of 3.6–100 ng/ml. More importantly, Ebola virus like particles (eVLPs) were able to be detected by this established virus detection measure. We produced and characterized two murine-derived mAbs (designated as 6E3 and 3F21) towards Zaire Ebola virus glycoprotein (GP), and established a sandwich ELISA based on the mAbs. It was suggested that the sandwich ELISA provided an alternative method for specific and sensitive detection of Ebola virus in the field setting.

Canine parvovirus type 2 (CPV2) is a highly contagious cause of serious and often fatal disease in young dogs. Despite the widespread availability of attenuated vaccines, safer, more stable, and more effective CPV2 vaccine candidates are still under exploration. Vaccinia virus (VV) has already been proved to be a safe, stable, and effective vaccine vector. In this study, we generated a VV-based CPV2 vaccine candidate (VV_-CPV-VP2) and then evaluated its immunogenicity in mice and dogs. The exogenous vp2 gene of CPV2, which replaced the major virulence gene hemagglutinin (ha) of VV, expressed efficiently and stably in vitro. Subsequently, intramuscular immunization of mice induced robust and lasting systemic immune responses, including neutralizing antibody against both CPV2a and CPV2b, and CPV2-VP2-specific interferon gamma (IFN-γ) secreting T cell. In addition, administration with a high-dose of VV_-CPV-VP2 did not cause significant side effects for mice, thus indicating marked safety of this vaccine candidate. Most importantly, a single-dose vaccination of VV_-CPV2-VP2 elicited substantial antibody responses and provided comparable protection for dogs with attenuated CPV2 vaccine. Collectively, this study demonstrated that VV_-CPV2-VP2 could be used as a promising vaccine candidate preventing CPV2 from infection for dogs.