Mosquito defensin facilitates Japanese encephalitis virus infection by downregulating the C6/36 cell-surface antiviral protein HSC70B

Heat shock protein 71 restricts mutation of porcine reproductive and respiratory syndrome virus nsp2 in vitro

porcine reproductive and respiratory syndrome (PRRS), caused by porcine reproductive and respiratory syndrome virus (PRRSV) infection, is an important swine infectious disease that causes substantial losses worldwide each year. PRRSV is a positive-sense single-stranded RNA virus that is highly susceptible to mutation and recombination, making vaccine and drug research for the disease extremely difficult. In this study, the binding of PRRSV nsp2 to HSP71 protein was detected by using the IP/MS technique. And the inhibitory effect of HSP71 on nsp2 antagonistic activity was validated by measuring NF-kB luciferase reporter. According to stress from inhibitory effects, the amino acid variation profile of PRRSV nsp2 under HSP71 stress was further analyzed using second-generation sequencing. Surprisingly, the results indicated that HSP71 pressure limits the random mutations of PRRSV nsp2 and maintains the dominant PRRSV strain within the population. Mutant strain showed weaker antagonistic activity and replication capability in cell. These results imply the binding of HSP71 with PRRSV nsp2 may lead to maintain the stability of highly virulent strains of PRRSV.

Liang-Ge-San inhibits dengue virus serotype 2 infection by reducing caveolin1-induced cytoplasmic heat shock protein 70 translocation into the plasma membrane

BACKGROUND

Dengue virus (DENV) is a major public health threat. However, there are no specific therapeutic drugs for DENV. Many Chinese heat-cleaning formulas, such as Liang-Ge-San (LGS), have been frequently used in the virus-induced diseases. The antiviral effect of LGS has not been reported yet.

PURPOSE

In this study, the effect of LGS on the inhibition of dengue virus serotype 2 (DENV-2) was investigated and the relevant mechanism was explored.

METHODS

High-performance liquid chromatography was applied to analyze the chemical characterization of LGS. The in vitro antiviral activities of LGS against DENV-2 were evaluated by time-of-drug-addition assay. The binding of heat shock protein 70 (Hsp70) and envelope (E) protein or caveolin1 (Cav1) were analyzed by immunofluorescence and immunoprecipitation assays. Then the role of Cav1 in the anti-DENV-2 effects of LGS was further examined. DENV-2 infected Institute of Cancer Research suckling mice (n = 10) and AG129 mice (n = 8) were used to examine the protective effects of LGS.

RESULTS

It was found that geniposide, liquiritin, forsythenside A, forsythin, baicalin, baicalein, rhein, and emodin maybe the characteristic components of LGS. LGS inhibited the early stage of DENV-2 infection, decreased the expression levels of viral E and non-structural protein 1 (NS1) proteins. LGS also reduced E protein and Hsp70 binding and attenuated the translocation of Hsp70 from cytoplasm to the cell membrane. Moreover, LGS decreased the binding of Hsp70 to Cav1. Further study showed that the overexpression of Cav1 reversed LGS-mediated E protein and Hsp70 inhibition in the plasma membrane. In the in vivo study, LGS was highly effective in prolonging the survival time, reducing viral loads.

CONCLUSION

This work demonstrates for the first time that LGS exerts anti-DENV-2 activity in vitro and in vivo. LGS decreases DENV-2-stimulated cytoplasmic Hsp70 translocation into the plasma membrane by Cav1 inhibition, thereby inhibiting the early stage of virus infection. These findings indicate that LGS may be a candidate for the treatment of DENV.

High-throughput sequencing-based Detection of Japanese encephalitis virus and its effect on micro ribonucleic acid

it was to explore the mechanism of Japanese encephalitis virus (JEV) and micro ribonucleic acid (miRNA) under high-throughput sequencing. 20 experimental mice, with good growth status and no disease infection, were selected. The cells used in the experiment included mouse microglial cell line (BV2), mouse neuroblastoma cell line (NA), and mouse brain endothelial cell line (bEnd.3). JEV titration was performed with JEV-infected cells, ribonucleic acid (RNA) in the cells was extracted, and finally the miRNA high-throughput sequencing data was analyzed. Agarose gel electrophoresis showed that the 28S and 18S electrophoresis bands were bright. Among the miRNAs detected in mouse brain tissues, 2986 were down-regulated and 1251 were up-regulated. Among miRNAs detected in NA cells, 4238 the decreasing expression and 2356 were expressed increasingly. In reducing miRNA expression, 1 multiplicity of infection (MOI) of P3 strain infection was more significant than 0.1 MOI. 10 miRNAs with significantly decreasing expression were miR-466d-3p, miR-381-3p, miR-540-3p, miR-466a-3p, miR-467a-3p, miR-574-5p, miR-199a-5p, miR-467a-5p, miR-674-5p, and miR-376b-3p. These were all obviously down-regulated in JEV-infected BV2, NA, and bEnd.3 neurons. High-throughput sequencing of JEV-infected mouse brain tissues and mouse neuronal cells found that JEV infection led to down-regulation of overall miRNA expression in host cells.

Japanese Encephalitis Virus Interaction with Mosquitoes: A Review of Vector Competence, Vector Capacity and Mosquito Immunity

Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus and a major cause of human viral encephalitis in Asia. We provide an overview of the knowledge on vector competence, vector capacity, and immunity of mosquitoes in relation to JEV. JEV has so far been detected in more than 30 mosquito species. This does not necessarily mean that these species contribute to JEV transmission under field conditions. Therefore, vector capacity, which considers vector competence, as well as environmental, behavioral, cellular, and biochemical variables, needs to be taken into account. Currently, 17 species can be considered as confirmed vectors for JEV and 10 other species as potential vectors. Culex tritaeniorhynchus and Culex annulirostris are considered primary JEV vectors in endemic regions. Culex pipiens and Aedes japonicus could be considered as potentially important vectors in the case of JEV introduction in new regions. Vector competence is determined by various factors, including vector immunity. The available knowledge on physical and physiological barriers, molecular pathways, antimicrobial peptides, and microbiome is discussed in detail. This review highlights that much remains to be studied about vector immunity against JEV in order to identify novel strategies to reduce JEV transmission by mosquitoes.

Mosquito Vector Competence for Japanese Encephalitis Virus

Japanese encephalitis virus (JEV) is a zoonotic pathogen mainly found in East and Southeast Asia and transmitted by mosquitoes. The objective of this review is to summarize the knowledge on the diversity of JEV mosquito vector species. Therefore, we systematically analyzed reports of JEV found in field-caught mosquitoes as well as experimental vector competence studies. Based on the investigated publications, we classified 14 species as confirmed vectors for JEV due to their documented experimental vector competence and evidence of JEV found in wild mosquitoes. Additionally, we identified 11 mosquito species, belonging to five genera, with an experimentally confirmed vector competence for JEV but lacking evidence on their JEV transmission capacity from field-caught mosquitoes. Our study highlights the diversity of confirmed and potential JEV vector species. We also emphasize the variety in the study design of vector competence investigations. To account for the diversity of the vector species and regional circumstances, JEV vector competence should be studied in the local context, using local mosquitoes with local virus strains under local climate conditions to achieve reliable data. In addition, harmonization of the design of vector competence experiments would lead to better comparable data, informing vector and disease control measures.