During 2003 - 2004, in total 976 sera and cerebrospinal fluid samples from patients with acute encephalitis syndrome (AES) were collected from Pediatric Hospital, several Centers of Preventive Medicine and National Institute of Hygiene and Epidemiology, Tay Nguyen for screening viral pathogens cause AES using MAC-ELISA with Japanese encephalitis (JE), West Nile and Nam Dinh virus antigens. Results: Out of 976 sera and cerebrospinal fluid samples of AES patients were screened using JE virus antigen, 46.1% (454/976) cases were confirmed to be JE virus infection. Out of 239 cerebrospinal fluid samples of AES patients were screened by Nam Dinh virus antigen, 13.4% (32/239) cases were confirmed to be Nam Dinh virus infection. Out of 103 sera and cerebrospinal fluid samples of AES patients were screened by West Nile virus antigen, there were no positive result was confirmed with this antigen. To date, JE virus is leading cause of AES in Vietnam, with over 80% cases in children under 15 years old. It should be intensive JE vaccination for all children under 15 years old in order to control JE soon.
Encephalitis, Japanese, West Nile virus

Acute viral encephalitis caused by neurotrophic viruses, such as mosquito-borne flaviviruses, is an emerging and re-emerging disease that represents an immense global health problem. Considerable progression has been made in understanding the pathogenesis of acute viral encephalitis, but the immune-pathological processes occurring during the progression of encephalitis and the roles played by various molecules and cellular components of the innate and adaptive systems still remain undefined. Recent findings reveal the significant contribution of Toll-like receptors (TLRs) and regulatory CD4+ T cells in the outcomes of infectious diseases caused by neurotrophic viruses. In this review, we discuss the ample evidence focused on the roles of TLRs and CD4+ helper T cell subsets on the progression of acute viral encephalitis. Finally, we draw attention to the importance of these molecules and cellular components in defining the pathogenesis of acute viral encephalitis, thereby providing new therapeutic avenues for this disease.
Communicable Diseases ; Dengue Virus ; Encephalitis ; Encephalitis Virus, Japanese ; Encephalitis, Viral ; Flavivirus ; T-Lymphocyte Subsets ; T-Lymphocytes ; Toll-Like Receptors ; West Nile virus

BACKGROUNDTo compare the biological characteristics of West Nile virus (WNV) and Japanese encephalitis virus (JEV), including cells sensitivity, pathogenicity, viral morphology, as well as the results of immunological and molecular biological detection.

METHODSCytopathic effect (CPE) and pathogenicity were observed in C6/36 cells and in suckling mice inoculated intracerebrally with the WNV or JEV, respectively. The sliced tissue samples for electron microscopic examination were prepared for the morphologic observation of the viruses. Serum antibody to WNV or JEV was detected using indirect immunofluorescence assay (IFA), and the viral RNA was analyzed by RT-PCR method.

RESULTSWNV or JEV-caused CPE was characterized by cell fusion and cell shedding, respectively. There was no significant difference in the pathogenicity to suckling mice between WNV and JEV. The morphologic observation showed that the shape and size of the two virions were similar. WNV and JEV were found to have antigenic cross-reactivity. The viral RNA could be detected from both WNV and JEV samples with universal primer set, but only nucleoside fragments of corresponding virus could be amplified when specific primers were used.

CONCLUSIONCPE in C6/36 cell and detection of the viral RNA should be useful in discrimination of WNV and JEV, and simultaneously examining the titers of serum antibodies against WNV and JEV may be helpful to diagnosis of infection with these agents.

Animals ; Brain ; virology ; Cell Line ; Diagnosis, Differential ; Encephalitis Virus, Japanese ; immunology ; isolation & purification ; Encephalitis, Japanese ; diagnosis ; virology ; Flavivirus Infections ; diagnosis ; virology ; Immunoglobulin G ; blood ; Mice ; Mice, Inbred BALB C ; West Nile virus ; immunology ; isolation & purification

BACKGROUND: The genus Flavivirus consists of many emerging arboviruses, including Dengue virus (DV), Japanese encephalitis virus (JEV) and West Nile virus (WNV). Effective preventive vaccines remain elusive for these diseases. Mice are being increasingly used as the animal model for vaccine studies. However, the pathogenic mechanisms of these viruses are not clearly understood. Here, we investigated the interaction of DV and JEV with murine bone marrow-derived dendritic cells (bmDC). METHODS: ELISA and FACS analysis were employed to investigate cytokine production and phenotypic changes of DCs obtained from bone marrow following flavivirus infection. RESULTS: We observed that these viruses altered the cytokine profile and phenotypic markers. Although both viruses belong to the same family, JEV-infected bmDC produced anti-inflammatory cytokine (IL-10) along with pro-inflammatory cytokines, whereas DV infection induced production of large amounts of pro-inflammatory cytokines (IL-6 and TNF-alpha) and no IL-10 from murine bmDCs. Both flaviviruses also up-regulated the expression of co-stimulatory molecules such as CD40, CD80 and CD86. JEV infection led to down-regulation of MHC II expression on infected bmDCs. We also found that cytokine production induced by JEV and DV is MyD88-dependent. This dependence was complete for DV, as cytokine production was completely abolished in the absence of MyD88. With regard to JEV, the absence of MyD88 led to a partial reduction in cytokine levels. CONCLUSION: Here, we demonstrate that MyD88 plays an important role in the pathogenesis of flaviviruses. Our study provides insight into the pathogenesis of JEV and DV in the murine model.
Animals ; Arboviruses ; Bone Marrow ; Cytokines* ; Dendritic Cells* ; Dengue Virus ; Down-Regulation ; Encephalitis Virus, Japanese ; Enzyme-Linked Immunosorbent Assay ; Flavivirus Infections ; Flavivirus* ; Humans ; Interleukin-10 ; Interleukin-6 ; Mice ; Models, Animal ; Tumor Necrosis Factor-alpha ; Vaccines ; West Nile virus

In light of global climate change, the seasonal and geographical distribution of vector species, especially mosquitoes, chigger mites, and ticks, are of great importance for human beings residing in rural and urban environments. A total of 12 species belonging to 4 genera have been identified as vector mosquitoes in the Republic of Korea. The most common of the 56 mosquito species in this country from 2013 through 2015 was found to be a malaria vector, Anopheles sinensis s.l. (species ratio [SR] 52%); followed by a potential vector of West Nile virus, Aedes vexans nipponii (SR 38%); a Japanese encephalitis vector, Culex tritaeniorhynchus (SR 6%); a West Nile virus vector, Culex pipiens (SR 3%); and a dengue and Zika virus vector, Ae. albopictus (SR 0.3%). Of the scrub typhus vectors, Leptotrombidium scutellare is the predominant chigger mite in Gyongnam province and Jeju island, whereas L. pallidum is the predominant species in other areas of Korea. Ticks were found to be prevalent in most environmental conditions, and high levels of their activity were consistently observed from May to September. Haemaphysalis species of ticks were mostly collected in grasslands, whereas Ixodes species were frequently found in coniferous forests. Haemaphysalis longicornis, known as the main vector of severe fever with thrombocytopenia syndrome, was the predominant species and was widely distributed throughout the country.
Aedes ; Anopheles ; Climate Change ; Communicable Diseases* ; Coniferophyta ; Culex ; Culicidae ; Dengue ; Disease Vectors* ; Encephalitis, Japanese ; Fever ; Forests ; Globus Pallidus ; Grassland ; Humans ; Ixodes ; Korea* ; Malaria ; Mites ; Republic of Korea ; Scrub Typhus ; Seasons ; Thrombocytopenia ; Ticks ; Trombiculidae ; West Nile virus ; Zika Virus