ObjectiveTo develop an ELISA method for quantitative determination of enterovirus 71 (EV71) antigen.The method can be applied to detect EV71 antigen contents and analyze the correlation between immunogenicity and immunoprotection.It also can be used for tissue culture infective dose( TCID50 ) assay.MethodsA double antibody sandwich ELISA method was developed for quantitative determination of EV71 antigen on the basis of the high-affinity neutralizing monoclonal antibodies ( K8G2 and Y8H2-HRP).This method was compared with microscopic observation for the detection of EV71 TCID50.The correlation was analyzed between the specific activity of EV71 antigen and the EV71 neutralizing antibody titer in immune serum.ResultsThe linear range of this method was 0.125-4.0 U/ml and the R2 value was 0.9911.The reagent did not react with other antigens except EV71 antigen.The recovery ratio of this method was 0.89-1.16.The coefficient of variation was less than 15％.The heat recovery rate was above 85％ when the reagent was in 37℃ for 9 days.There was a good correlation in TCID50 of EV71 between this method and microscopic observation,r=0.990.The specific activity of EV71 antigen had positive correlation with the neutralization titer of immune serum in 21 EV71 strains,r=0.930.ConclusionThe quantitative ELISA method for EV71 antigen was developed,which could be used to detect EV71 antigen contents and analyze TCID50.The specific activity of EV71 antigen detected by the method could be used to evaluate the immunoprotection of the vaccine potency test.

Objective: To learn the toxicity of Dendrobium officinale flowers to pregnant rats ( P, F1 ) and offspring rats ( F1, F2 ) before birth, so as to provide toxicological evidence for the safety assessment. Methods : The rats were divided into four groups with 20 female rats and 10 male each. The rats in three dose groups were fed with Dendrobium officinale flowers at the dose of 2.0, 4.0, 6.4g/kgbw. After two generation, the F1a and F2a rats were fed with basal diet; F1b and F2b rats were fed with Dendrobium officinale flowers. The body weights and total weight gains during the gestation, the conception rates, the pregnancy rates, the birth weights and survival rates of offspring rats were examined. Results: There were no statistically significant differences in the body weights and total weight gains during the gestation, the conception rates, and the pregnancy rates in pregnant rats ( P, F1 ) among the four groups ( P>0.05 ). There were also no statistically significant differences in the survival rates and live birth rates in offspring rats (F1, F2) between the dose groups and the control group ( P>0.05 ). Conclusions Dendrobium officinale flowers did not show obviously adverse effects on pregnant rats ( P, F1 ) and offspring rats ( F1, F2 ) before birth.

As a potential vectored vaccine,Newcastle disease virus(NDV)has been subject to various studies for vaccine development,while relatively little research has outlined the immunomodulatory effect of the virus in antigen presentation.To elucidate the key inhibitory factor in regulating the interaction of infected dendritic cells(DCs)and T cells,DCs were pretreated with the NDV vaccine strain LaSota as an inhibitor and stimulated with lipopolysaccharide(LPS)for further detection by enzyme-linked immunosorbent assay(ELISA),flow cytometry,immunoblotting,and quantitative real-time polymerase chain reaction(qRT-PCR).The results revealed that NDV infection resulted in the inhibition of interleukin(IL)-12p40 in DCs through a p38 mitogen-activated protein kinase(MAPK)-dependent manner,thus inhibiting the synthesis of IL-12p70,leading to the reduction in T cell proliferation and the secretion of interferon-γ(IFN-γ),tumor necrosis factor-α(TNF-α),and IL-6 induced by DCs.Consequently,downregulated cytokines accelerated the infection and viral transmission from DCs to T cells.Furthermore,several other strains of NDV also exhibited inhibitory activity.The current study reveals that NDV can modulate the intensity of the innate?adaptive immune cell crosstalk critically toward viral invasion improvement,highlighting a novel mechanism of virus-induced immunosuppression and providing new perspectives on the improvement of NDV-vectored vaccine.