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Background & Objectives: Lepidopteran cell cultures and baculovirus expression vector systems are becoming popular due to their potential applications in biotechnology especially for the expression of foreign proteins. Efforts were made to develop new, indigenous, cell lines from Bombyx mori larvae and pupae., Methods: Eight to ten B. mori larvae and 10-12 pupae were surface sterilized, dissected and ovaries were removed aseptically. Ovaries were chopped finely, washed and suspended in growth medium. When the cells formed monolayers, they were subcultured and experiments were carried out., Results: Two new cell lines from larval and pupal ovaries of B. mori were established in Grace's insect tissue culture medium supplemented with 20 per cent FBS (foetal bovine serum). The larval cell line consisted predominantly of epithelial-like cells (98.31%), whereas the pupal cell line had a mixed cell population of epithelial-like (71.8%) and fibroblast-like cells (27.8%). Karyology indicated a typical lepidopteran pattern in both the cell lines and had chromosome numbers ranging from 35 to 150 and 60 to 180 for larval and pupal ovaries respectively. Four-fold increase in cell number was observed in these cell lines in 7 days. Both the cell lines were found susceptible to B. mori multiple nucleopolyhedrovirus and Autographa californica multiple nucleopolyhedrovirus, but not to Helicoverpa armigera single nucleopolyhedrovirus and Spodoptera litura multiple nucleopolyhedrovirus., Interpretation & Conclusion: These well characterized cell lines may be of immense application in biotechnology and medicine for the production of biologically active recombinant proteins to use in vaccine studies as well as in therapeutic applications.

A strain of Japanese encephalitis (JE) virus has been isolated from a pool of female mosquitoes of C. tritaeniorhynchus, using C. bitaeniorhynchus cell line. This is the first report of JE virus isolation from mosquitoes in Gorakhpur district of Uttar Pradesh, north India.

The susceptibility of the newly established Ae. krombeini cell line (NIVI-AK-453) to six arboviruses, belonging to four different families, was studied. Sindbis (SIND), Vesicular stomatitis (VSV) Chandipura (CHP) and African horse sickness (AHS) viruses multiplied in these cultures. A four-to-five-fold increase in the virus titres was observed. The maximum titre of SIND, VSV, CHP and AHS viruses were observed on 1st, 4th, 3rd and 10th post infection days, respectively. A steady and significant increase in the titre of AHS was observed over a period of ten days. The sandfly fever virus (SFV) and the tick-borne, Kaisodi virus did not multiply in the cultures.

A strain of Japanese encephalitis virus was isolated from a pool of 54 female C. pseudovishnui Colless, 1957. The mosquitoes were collected in August 1988 during the period of epidemic of JE. This is the first report of isolation of JE virus from mosquitoes in Goa in the western coastal belt of peninsular India. In view of this isolation, C. pseudovishnui acquires greater importance, even though its density and relative prevalence during the current study was found to be far lower than C. tritaeniorhynchus.

Twenty one strains of Japanese encephalitis (JE) virus, including 16 from India, were compared antigenically on the basis of their reactivity in immunofluorescence (IF), haemagglutination inhibition (HI), ELISA with captured antigen (ECA), and neutralization (N) tests with JE monoclonal antibodies (MAbs). These MAbs represented three domains of distinct epitopes on the envelope protein, designated as Hs-1 to 4 (JE specific in HI), Hx-1 to 5 (flavivirus cross reactive in HI) and NHs-1 to 2 (non-HI JE virus specific). Fifteen of the 21 strains studied were placed in group I. These reacted with MAbs representing the three domains in all the tests indicating presence of the three types of epitopes with full functional activity. The remaining six strains were placed in group II and showed loss in HI reactivity with Hs MAbs but not with Hx MAbs. All the group II strains also reacted in IF and ECA with NHs-1. Hs epitopes in three strains, G9473 (Tamil Nadu), 641686 (Tamil Nadu) and 822199 (Karnataka), appeared to have mutated partially, indicating loss in HI reactivity with Hs MAbs only, while there was retention of other reactivities, viz., IF, ECA and to some extent N test with G9473 and 641686. The remaining three strains, 691004 (Sri Lankan), 755468 (West Bengal) and Yoken (Japan) of group II showed almost complete loss of Hs-1 and Hs-2 epitopes as there was absence of reactivity in IF, ECA and N test in addition to HI. However, Hs-3 MAb showed reactivity in IF with these strains.(ABSTRACT TRUNCATED AT 250 WORDS)