Our findings suggest that this outbreak of acute encephalitis in Andhra Pradesh was associated with Chandipura virus, adding to the evidence suggesting that this virus should be considered as an important emerging pathogen.

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.

Japanese encephalitis (JE) is a serious public health concern in most of Asia. The disease is caused by JE virus (JEV), a flavivirus transmitted by Culex mosquitoes. Several vaccines have been developed to control JE in endemic areas as well as to protect travelers and military personnel who visit or are commissioned from non-endemic to endemic areas. The vaccines include inactivated vaccines produced in mouse brain or cell cultures, live attenuated vaccines, and a chimeric vaccine based on the live attenuated yellow fever virus 17D vaccine strain. All the marketed vaccines belong to the JEV genotype III, but have been shown to be efficacious against other genotypes and strains, with varying degrees of cross-neutralization, albeit at levels deemed to be protective. The protective responses have been shown to last three or more years, depending on the type of vaccine and the number of doses. This review presents a brief account of the different JE vaccines, their immunogenicity and protective ability, and the impact of JE vaccines in reducing the burden of disease in endemic countries.

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The maturation of the specific antibody response to foreign antigens (Ags)' has been thoroughly investigated in experimental animals (1-8). A first in vivo exposure to Ag induces a "primary" antibody response constituted mainly of IgM with relatively low affinity for the inducing Ag. A second and any further exposure to the same Ag evoke "secondaries" or "memory" responses that involve mainly IgG with a higher affinity for the Ag. Although study ofthe human antibody response to some Ags, e.g., tetanus toxoid (TT) and keyhole limpet hemocyanin, has been attempted (9-13), the enormous difficulty in generating human mAbs (14, 15) has hindered the definition of the clonal basis of such responses.The recent progress made in the generation of human mAb-producing cell lines (14-21) and in the characterization of novel B cell subsets (22, 23) allowed us to investigate the human antibody response to self and exogenous Ags at the clonal level (16)(17)(18)(19). In the present studies, we quantitated the circulating B cells committed to the production of antibodies to rabies virus and determined their phenotype in healthy humans before and after multiple administrations of inactivated rabies virus vaccine. Moreover, using EBV transformation and somatic cell hybridization techniques, we constructed 10 cell hybrids secreting IgM, IgG, and IgA mAbs to the virus. We found that in the preimmune B cell repertoire, circulating lymphocytes committed to the production ofvirus-binding IgM, but not IgG or IgA antibodies, are present in high number. These cells are surface CD5+ and the antibodies they produce are polyreactive and low affinity. After vaccination with inactivated rabies virus, B lymphocytes producing monoreactive high affinity IgG and IgA antibodies to the virus consistently appear in the circulating. Most ofthese cells are surface CD5-and account for >10% of the total IgG-and IgA-producing cell precursors, respectively.