An outbreak of viral encephalitis occurred in northern India in 2006. Attempts to identify an etiologic agent in cerebrospinal fluid by using reverse transcription–PCR showed positivity to enterovirus (EV) in 66 (21.6%) of 306 patients. Sequencing and phylogenetic analyses of PCR products from 59 (89.3%) of 66 specimens showed similarity with EV-89 and EV-76 sequences.
During investigations into the outbreak of encephalitis in 1996 in the Kerala state in India, an arbovirus was isolated from a Culex tritaeniorhynchus mosquito pool. It was characterized as a Japanese encephalitis and West Nile virus cross-reactive arbovirus by complement fixation test. A plaque reduction-neutralization test was performed using hyperimmune sera raised against the plaque-purified arbovirus isolate. The sera did not show reactivity with Japanese encephalitis virus and were weakly reactive with West Nile virus. Complete open reading frame sequence analysis characterized the arbovirus as Bagaza virus (BAGV), with 94.80 % nucleotide identity with African BAGV strain DakAr B209. Sera collected from the encephalitic patients during the acute phase of illness showed 15 % (8/53) positivity for anti-BAGV neutralizing antibodies. This is the first report of the isolation of BAGV from India. The presence of anti-BAGV neutralizing antibodies suggests that the human population has been exposed to BAGV.An outbreak of Japanese encephalitis (JE) was reported from the Allapuzza, Thiruvanthapuram and Kottayam districts of Kerala state, India, during 1996. Only 33 % (50/ 150) of the sera collected from hospitalized cases were confirmed as JE by immunoglobulin M (IgM) ELISA. Other clinical specimens were not available for further investigations. Entomological investigations during the outbreak were carried out and 184 mosquito pools collected from the affected area were processed for isolation in 2-day-old Swiss mice by the intra-cranial route (Rodrigues et al., 1980;George et al., 1984). One pool from Culex tritaeniorhynchus showed sickness in inoculated mice. Brains from sick mice were harvested and suspended in 10 % bovalbumin phosphate saline. The suspensions were stored at 270 u C and designated as the arbovirus isolate (96363). The isolate showed cross-reactivity with anti-JE virus (JEV) and anti-West Nile virus (WNV) immune sera in a complement fixation (CF) test (Pavri & Ghosh, 1969; Rodrigues et al., 1980;Damle et al., 1998).The isolate did not react with immune sera raised against other circulating arboviruses, including Chandipura (Rhabdoviridae), Sindbis (Togaviridae), Chikungunya (Togaviridae), Kyasanur forest disease (Flaviviridae), Batai (Bunyaviridae) and Dengue (Flaviviridae) viruses (Paul et al., 1970; Rodrigues et al., 1980;George et al., 1984).In this study, we present the genetic characterization of the arbovirus isolate and serological analysis of available sera collected from encephalitis patients during 1996. The Institutional Animal Ethical Committee approved this work and ethical guidelines were strictly followed according to their recommendations. The arbovirus isolate was plaque-purified to rule out the possibility of isolation of both JEV and WNV from the mosquito pool. The mouse brain stock of the arbovirus isolate was passaged twice in porcine stable kidney (PS) cells to amplify the virus. A single plaque was selected from the first PS cell passage and then subjected to two sequential ...
Experiments were carried out to demonstrate the susceptibity and transmission potential of Phlebotomus argentipes (Annandale & Brunetti) for Chandipura virus (CHPV). In India, P. argentipes is one of the predominant species found in many areas endemic for CHPV. Although its laboratory colonization is difficult, we have demonstrated that 65% of P. argentipes were susceptible to CHPV infection by the oral route. Transmission experiments were carried out by intrathoracic inoculation because of re-feeding problems with this species. After incubation for 24 hours, efficient transmission of CHPV to mice was observed. The estimated minimum transmission rate among the inoculated flies was 32%. CHPV in sand flies as well as in mice was detected and confirmed by immunofluorescent antibody assay and reverse transcription-polymerase chain reaction, respectively. The susceptibility of P. argentipes to CHPV and its potential to transmit the virus by bite has importance in epidemiology of CHPV.
Experiments were conducted in the laboratory on Phlebotomus papatasi to determine the possible role of males in maintaining or sustaining the Chandipura virus (CHPV) activity in nature. This study indicated that infected males are capable of passing on the virus to female sand flies while mating. The infection rate was found to be 12.5% in uninfected females when mated with infected males. The occurrence of venereal transmission of this virus may have epidemiologic importance in the natural cycle of CHPV.
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