1Division of Virology, Defense R & D Establishment (DRDE), Jhansi Road, Gwalior-474 002, Madhya Pradesh.
212, Air Force Hospital, Gorakhpur, India.
3Department of Pediatrics, B.R.D. Medical College, Gorakhpur, India.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Japanese encephalitis virus (JEV) is a major public health concern in Asia including India with a case fatality of 25%. An epidemic of viral encephalitis was reported from July to September 2005 in Gorakhpur affecting 4000 persons with more than 1000 deaths. A total of 326 febrile patients with clinical symptoms of encephalitis were investigated for presence of JEV specific antibodies and genomic RNA in both serum as well as CSF samples. A nitrocellulose membrane based indirect enzyme immunoassay (EIA) was standardized for detection of IgM and IgG antibodies in patient serum as well as CSF employing sucrose gradient purified cell culture antigen. The detection of genomic RNA of the virus was accomplished by RT-PCR employing the two sets of primers targeting Envelope (E) and NS1 gene. The serosurveillance of the 326 samples comprising 185 serum and 141 CSF samples analysed in this study indicated an overall 50% and 30% seropositivity with serum and CSF samples respectively. The antibody profile of these serum samples revealed 23% IgM, 19% IgG and 7% both IgM and IgG positivities as compared to 26% IgM, 4% IgG and 1% both IgM and IgG positively in CSF samples. The RT-PCR analysis of all the serum and CSF samples, revealed virus specific 345 bp and 166 bp amplicons for Envelope and NS1 genes respectively in 10 (3%) samples only. Further analysis of these amplicons by sequencing revealed = 95% homology with JE virus up on blast search. The final confirmation of the viral etiology was established by virus isolation in C6/36 cells and subsequent identification through nucleotide sequencing. The phylogenetic analysis revealed that these isolates of JE virus responsible for Gorakhpur-2005 epidemic belong to the genogrpup-III but forms a separate cluster as compared to earlier isolates. Thus the present study established the continued predominance of JE virus as the major etiological agent of viral encephalitis in eastern Uttar Pradesh and thereby demanding implementation of specific control measures to prevent further recurrence of such epidemics.
