Biophysical characterization of Japanese encephalitis virus (KV1899) isolated from pigs in Korea

A virus strain, showing cytopathic effect in Vero cell, was isolated from plasma of a fattening pig in Gyeonggi province, Korea in October 1999. The evaluation of physicochemical/biological properties of the isolate showed that the virus, KV1899, inoculated suckling mouse showed paralysis and died within 7 days post-inoculation, the mouse brain suspension had hemagglutinating activity with goose RBC. Pathogenicity of isolate was carried out by intracranial and intraperitoneal inoculation of 3-4 weeks mice. The mice inoculated with isolate showed 10 4.5 LD50/ 0.03 ml and 10 3.0 LD50/0.5 ml according to the inoculation route. The isolate was identified as RNA and enveloped virus using IUDR and chloroform sensitivity test. The virus particles within the infected Vero cell were measured to be 40-50 nm in size by electron microscopy. The isolate was further characterized by immuno-fluorescence assay using Japanese encephalitis virus (JEV) specific monoclonal antibodies. Reverse transcription polymerase chain reaction (RT-PCR) revealed the presence of JE specific conserved sequences in this isolate. The artificially inoculated pigs had HI titer of 320 to 2,560 against JEV at 14 to 42 days post inoculation. We confirmed this isolate as Japanese encephalitis virus. It was the second isolation of JEV in pigs in Korea.

Clinical, radiological and neurophysiological spectrum of JEV encephalitis and other non-specific encephalitis during post-monsoon period in India.

AIMS: To study the spectrum of encephalitis during the post-monsoon period in a tertiary care centre of India. METHODS: Clinical, neurophysiological and radiological features of patients with encephalitis are reported in this communication. The patients were subjected to clinical examination, CT or MRI scan, EEG, motor and somatosensory evoked potentials in both upper and lower limbs bilaterally and concentric needle electromyography. The laboratory studies for Japanese encephalitis (JE) comprised virus isolated, IgM capture ELISA, mercaptoethanol test and hemagglutination inhibition titre in paired sera against JE virus. Patients were classified into JEV encephalitis and non-specific encephalitis. On the basis of radiological features, they were classified into group I (thalamic or basal ganglia involvement), group II (brainstem involvement only) and group III (normal MRI). The outcome was defined into poor (bedridden), partial (dependent for daily activities) and complete (independent) recovery at the end of 3 months. RESULTS: Out of 26 patients (Age 7-70 years, mean 24.8 years), laboratory evidences of JEV infection was present in 14 patients and one patient had herpes simplex encephalitis. The patients with JEV encephalitis had more severe illness as evidenced by lower GCS score, higher frequency of anterior horn cell involvement, movement disorders and more extensive MRI changes. The EEG and MEP changes were also more frequently abnormal in the JEV group. On radiology, 15 patients had thalamic or basal ganglia involvement (group I), 3 isolated midbrain involvement (group II) and 8 had normal MRI (group III). Laboratory evidence consistent with JE were present in 11 out of 12 patients in group I and 3 out of 8 in group III, however, there was no laboratory evidence of JE virus infection in patients with isolated brainstem involvement. There was overlap in the neurologic and systemic manifestations in all the 3 radiological groups as well as in the groups with and without laboratory evidences of JEV infection. CONCLUSION: The observed overlap in neurological and systemic involvement in different subgroups of encephalitis may be due to JE or JE-like viral infection. The possibility of strain variation, change in virulence of organism or immunity of host needs further studies.