Genetic characterization of Bagaza virus (BAGV) isolated in India and evidence of anti-BAGV antibodies in sera collected from encephalitis patients

Abstract

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 ...

Natural Bagaza virus infection in game birds in southern Spain

“…Pathology due to BAGV infection had previously not been described in any species as the presence of neutralizing antibodies against BAGV in persons with acute encephalitis in India, could not link the infection clearly to disease symptoms [11]. However, based on sequence analysis, BAGV has been shown to be synonymous to Israel turkey meningoencephalitis virus (ITV) [12], which causes a disease characterized by nonpurulent meningoencephalitis with lymphocytic perivascular infiltrates and focal myocardial necrosis in turkeys in Israel and South Africa, and is controlled by vaccination with live attenuated vaccines [13-15].…”

Tembusu Virus in Ducks, China

“…HQ641388) was shown to encode the nonstructural (NS) 1 protein of flavivirus, which exhibited 73%–85% identity to flaviviruses in the Ntaya virus and Japanese encephalitis virus groups, such as Bagaza virus (GenBank accession no. ACG60714 [ 3 ],) and St. Louis encephalitis virus (GenBank accession no. ABN11829 [ 4 ]).…”

“…The primers were located in the conserved regions of the NS3 sequences of Bagaza virus, St. Louis encephalitis virus, and Usutu virus ( 3 – 5 ) and were predicted to produce an ≈400-bp amplicon. The reaction conditions were as follows: 5 min at 94°C; followed by 38 cycles of denaturation at 94°C for 40 s, annealing at 47°C for 35 s, and extension at 72°C for 1 min; and a final extension of 72°C for 10 min.…”

Duck egg drop syndrome virus: an emerging Tembusu-related flavivirus in China

“…Notably, the flaviviruses, including TMUV [33,34] and BAGV [5,68], that cross-react with DEDSV are all infectious to human beings. Given the close phylogenetic relationship with YFV, DENV, TBEV, and JVE group viruses, as well as the same CS pattern with JEV group viruses [15], DEDSV has high potential to be a zoonotic pathogen.…”