The present and future of veterinary vaccines for Japanese encephalitis in Korea

Japanese encephalitis (JE) is a mosquito-borne zoonotic disease that affects approximately 50,000 people annually in Asia, causing 10,000 deaths. Considering the role of pigs as the virus-amplifying host and the economic loss in the swine industry, JE is an important disease for both public and animal health. A nationwide JE virus (JEV) vaccination program has been conducted annually for more than 30 years to prevent severe reproductive disorders in the Korean sow population. Remarkable progress in molecular biology has made it possible to analyze the genome of the vaccine strain at the nucleotide and amino acid levels. However, the scientific record of the current JEV veterinary vaccine has not been reported. Therefore, this article outlines the current JEV vaccine strain used in animals and discusses future directions for developing new veterinary JEV vaccines.

Construcion of a chimeric Japanese encephalits virus/dengue virus-2 / 病毒学报

The prM/E gene of DV2 was cloned into the JEV (SA14-14-2 strain) replicon vector which had been constructed previously, and the resulting recombinant plasmid was named pPartialdeltaprM/E. The constructed chimeric clone was linearized and then was transcripted into RNA in vitro. The produced RNA was transfected into BHK-21 cells. Five to seven days later, CPE could be observed on the transfected BHK-21cells, and then the supernatant containing the chimeric virus was collected. The Supernatant was inoculated to BHK-1 cells and C6/36 cells, respectively. CPE could be observed about 4 days post the infection of C6/36cell with the chimeric virus. The results from RT-PCR, IFA, Western blot showed that the virus contained the chimeric RNA and the envelop protein of DV2. However, the chimeric virus could not be passaged in BHK-21 cell. The successful construction of the infectious clone JE/DEN-2 laid the basis for the further research of the DV vaccine.

Encefalite do Nilo Ocidental, nossa próxima epidemia? / Encephalitis of ocidental Nilo, disease outbreaks?

Neste trabalho, foram revistas as características clínicas e epidemilógicas das infecções pelo Vírus do Nilo Ocidental (VNO), destacando modo de transmissão, reservatórios e vetores, bem como a distribuição geográfica de aves reservatórias e suas rotas de migração no continentre americano, de forma a embasar a discussão das possibilidades de introdução do vírus no Brasil e a preposição de estratégias de vigilância adequadas à nossa realidade. A revisão foi realizada pela consulta à base de dados MEDLINE, no período 1991-2002, complementada pela utilização dos textos encontrados atrravés de mecanismos de busca da página dos Centers for Disease Control and Prevention (CDC) (home page na internet: cdc.gov.). Foram também consultados livros-texto de rconhecimento internacional, nas disciplinas pertinentes ao desenvolvimento do estudo. OVNO é um arbovírus transmitido pela picada de mosquitos infectados. o vírus infecta principalmente aves, homens e eqüinos. No homem, pode produzir desde quadros oligossomáticos até casos graves e fatais de encefalite

Japanese encephalitis in Vietnam during 1991-2001

The Japanese encephalitis Circulated in Vietnam, especially in the delta provinces of Northern Vietnam. The yearly morbidity rate was 3-5 /100.000 rehabitants. The disease occurred mainly in ages of 1-15, highest in ages of 5-9 and followed by ages of 1-4 and in the summer (May, June, July). Vietnam manufactured the vaccine of encephalitis. It should strengthen the health communication and education and expanded immunization for susceptible ages

Japanese encephalitis control by Japanese encephalitis vaccine in Expanded Program of Immunization in Vietnam

The outcomes of vaccination in 1 to 5-year children were surveyed in high-risk districts between 1997 and 2001. The Japanese encephalitis vaccination schedule as follows: In the first years, the children receive 2 injections with 1-week interval, in the next year they receive the third injection. The injection dose is 0.5 ml subcutaneous. Results: For 5 years continuously, there were 1,472,608 one to five-year children had immunized, reached rate of 94.7% in 90 high-risk districts. The program produced dramatic effect on prevention. The incidence of Japanese encephalitis dropped gradually over years. By 2002, the cases reduced by one third in comparison with previous time

Antibody response of immunized children to Japanese encephalitis virus clinical isolate HNH 639

57 school children were immunized with the Japanese encephalitis (JE) veccine produced at NIHE, Hanoi (Nakayama vaccine strain). One year after the third dose, their sera were examined for the presence of antibodies against a JE virus clinical isolate (HNH 693, isolated in North VietNam). The results showed that 100% of the serum samples had high antibody titers against both HNH 693 and Nakayama strains. the antibody titer against 693 was significantly higher than thatagainst Nakayama. Potency testing of 11 batches of NIHE-JE vaccine were carried out using parallely HNH 693 and Nakayama as challenge strains. It showed that all these 11 vaccine batches had high potency against both challenge strains (2.62 with HNH 693 and 2.38 with Nakayama).

Viral encephalitis of public health significance in India: current status.

Japanese encephalitis (JE) and rabies are 2 viral encephalitis that are of public health importance in India. JE is a zoonosis with the primary cycle occurring in arthropods (mosquito vectors) and vertebrate animals (primarily the pig), man being only an incidental 'dead end' host. Out-breaks have been seen in most parts of India except the north west. The disease presents with a prodromal stage, an acute encephalitic stage with coma, convulsions and variable deficits and a convalescent stage. Diagnosis can be made by viral isolation from CSF or brain, or serologic tests such as haemagglutination inhibition test and IgM antibody capture ELISA in CSF and blood. There is no specific treatment. Mortality ranges from 20-50% and almost half the survivors have sequelae. The most effective control measure besides control of mosquitos is vaccination. A killed mouse brain vaccine is being prepared in India and is safe and effective but expensive. Rabies is a highly fatal encephalomyelitis primarily occurring in urban dogs and wild animals especially canines. It is endemic in India and affects an estimated 3 per 100,000 persons annually. The patient initially may display bizarre combative behaviour. The disease can be effectively prevented by post exposure vaccination. The nervous tissue vaccine is no longer recommended because of unacceptable neurotoxicity. Three cell culture vaccines are presently available with about equal efficacy.

Sensitivity of particle agglutination assay with MAC-ELISA for Japanese encephalitis rapid diagnosis: a comparative study

Particle agglutination assay (PA) was developed and applied for detecting specific IgM antibodies to Japanese encephalitis virus in recent years. In this study, the sensitivity of PA and MAC-ELISA were 91.11 and 97.77%, respectively

Changes in results of Japanese encephalitis (JE) serodiagnosis in Northern Vietnam, 1998

During the 1998 Japanese Encephalitis epidemic in Northern Vietnam the authors have examined 402 patients which were clinically diagnosed as "acute encephalitis syndrome". The IgM anti JE was evidenced in only 132 cases. The seropositivity is patients under 5 years of age was 33.0 - 42.1% in 1998, compared with 64.2 - 75.7% during the period of 1989 - 1995.

Motor disorder among pediatric patients with Japanese encephalitis after acute stage

During the 1997-2000, 62 children patients with Japanese encephalitis were treated at the Pediatric Department, Vietnam Institute of Traditional Medicine for motor sequelae. The age range was from 8 months to 15 years, and 27 of them were girls. All of them had motor disorders as follows:-52 cases with tetraplegia.-43 cases with severe and complete paralysis (according to Henry degree)- 57 cases with spastic paralysis, and 5 cases with flaccid paralysis.-34 cases with extrapyramidal contracture, and 32 cases with marked axial dystonia

Japanese encephalitis virus antibody among normal individuals of Dibrugarh area, upper Assam.

In a hospital based study in Dibrugarh upper Assam carried out over a period of one year, 250 normal individuals, were screened for antibody to Japanese encephalitis Virus. 44 individuals (17.6%) showed antibody to JE virus. The highest numbers were found in July and August, each 40%, and lowest in January (4%). The ratio of apparent to inapparent infection in this study was found to be 9.1 : 100, which is lower than reported in Assam earlier, but slightly higher than predicted for India as a whole.

Expression of the Japanese encephalitis virus NS3 and NS2b proteins as glutathione S-transferase fusions.

Flaviviruses generate their structural and nonstructural proteins by proteolytic processing of a single large polyprotein precursor. These proteolytic events are brought about both by host cell signalase and a virally encoded protease. The virally encoded proteolytic activity has been shown to reside within the nonstructural protein 3 (NS3) and requires the product of the nonstructural 2b (NS2b) gene. In order to obtain sufficient quantities of pure NS2b and NS3 proteins for kinetic analysis, we have expressed both these proteins in recombinant systems as fusions to glutathione S-transferase (GST). The fusion constructs were driven by the strong bacteriophage T7 promoter. Transfection of these constructs into the African green monkey kidney cell line CV-1 previously infected with a recombinant vaccinia virus expressing the T7 RNA polymerase resulted in synthesis of the fusion proteins. Both the fusion proteins could be purified to homogeneity in a single step using a glutathione agarose affinity matrix.

Comparative evaluation of bioassay and ELISA for detection of Japanese encephalitis virus in field collected mosquitos.

Comparative evaluation of enzyme-linked immunosorbent assay (ELISA) and bioassay (virus isolation in Toxorhynchites splendens larvae and identification by immunofluorescence test using virus specific monoclonal antibody) was carried out in order to define a suitable strategy for monitoring Japanese encephalitis virus infection in field mosquitos. A total of 8,850 adult female mosquitos in 177 pools (Culex tritaeniorhynchus 91, Cx. vishnui 59 and Cx. fuscocephala 27) collected from an endemic area of Tamil Nadu were examined by both the techniques. In ELISA, 9 pools which had optical densities (OD) equal to the mean of normal infected pools plus > or = 4 standard deviations (SD) mean considered positive and all of them were virus positive by the bioassay also. Sixty-five pools had OD = Mean + 2-3 SD and 103 pools had OD = Mean + < 2 SD of normal pools. From these groups, 12 (18.5%) and 8 (7.8%) pools respectively were found to be virus positive by the bioassay. In total 29 (16%) pools were positive by the bioassay as against 9 (5%) by ELISA. This study demonstrated that the bioassay is sensitive for estimation of true positives and ELISA is a rapid screening system. A protocol has now been developed for surveillance in which field pools are first screened by ELISA and only those with OD = Mean + > or 2 SD are assayed in Toxorhynchites. By excluding a large majority of pools with low OD (Mean + < 2 SD), which are likely to yield to only a small percentage of true positives, the cost, time and labor involved are greatly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)