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S N Ghosh

Publications and source records attributed to S N Ghosh.

At least 37 records · Page 2Linked to original sources
PubMed1990

Selection of a neutralization-escape variant strain of Japanese encephalitis virus using monoclonal antibody.

An Indian strain of Japanese encephalitis virus (JEV), 733913, a human isolate from Bankura, West Bengal in 1973, with all the functional epitopes designated by a panel of murine monoclonal antibodies (MAbs), was treated with one of the JEV specific HI reactive MAb(Hs-I). This led to selection of a neutralization-escape variant which showed loss of reaction to three different MAbs belonging to the same domain (Hs) and assumed similar characteristics to another JEV strain (755468) also isolated from Bankura in 1975 from mosquitoes. It is possible that selection of such variant might occur in presence of pre-existing JE antibody (Hs-I type) in pigs which are amplifying hosts of JEV. Subsequent dissemination of such variant virus could occur through mosquitoes.

Animals↗
PubMed1990

Protective effect of 6-MFA, a fungal interferon inducer against Japanese encephalitis virus in bonnet macaques.

6-MFA, an extract from the fungus Aspergillus ochraceus was administered to 8 bonnet macaques. An equal number of monkeys matched for age, sex and weight received placebo and served as controls. Twenty hours after the administration of the 6-MFA/placebo the monkeys were challenged with an Indian strain of Japanese encephalitis virus by the intranasal route. Signs and symptoms of the disease such as fever, tremors, loss of appetite, dehydration, flaccid paraplegia or quadriplegia were pronounced in all the control monkeys, while in the 6-MFA treated group only two developed symptoms. Virus could be isolated from only one of the 6-MFA treated monkeys on day 6, and from four control monkeys; one each from CSF, spinal cord, blood and from both nasal swab and blood of the fourth monkey. The appearance of HI and N antibodies in 6-MFA treated group was either delayed or completely suppressed. The results indicate that 6-MFA is a potential antiviral agent which can be used to reduce the morbidity and mortality in bonnet macaques (Macaca radiata) experimentally infected with Japanese encephalitis virus.

Animals↗
PubMed1989

Route-related variation in the immunogenicity of killed Salmonella enteritidis vaccine: role of antigen presenting cells.

In order to assess the role of the route of immunization on the immunogenicity of killed Salmonella vaccine, mice were immunized with killed S. enteritidis by intraperitoneal (i.p.) and intradermal (i.d.) routes. Whereas the former was non-immunogenic, the i.d. immunization generated an excellent delayed-type hypersensitivity response; further, i.p. immunization could even suppress the subsequent i.d. immunization. Since the peritoneal macrophages (MO) are known to be particularly low in Ia or MHC-class II antigens, so essential for antigen presentation, the non-immunogenicity by i.p. route was thought to be due to their poor presentation efficiency. Poly I: poly C, an interferon inducer, is known to enhance the MHC-class II expression; hence effect of poly I: poly C treatment on the immunogenicity of the killed vaccine by i.p. route was tested and indeed the non-immunogenicity was corrected. Poor efficiency of presentation of S. enteritidis antigen by peritoneal cells and its improvement by prior poly I: poly C treatment was further confirmed by in vitro lymphocyte transformation test using primed T cells and peritoneal cells from normal and poly I: poly C treated mice. Poly I: poly C treatment also enhanced expression of Ia antigens on peritoneal cells.

Animals↗
PubMed1989

Epitope analysis of strains of Japanese encephalitis virus by monoclonal antibodies.

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)

Animals↗
PubMed1989

Interferon producing capacity (IPCA) of peripheral mononuclear cell in oral cancer patients.

Interferon producing capacity (IPCA) of peripheral blood mononuclear cells is ability of these cells to produce IFN with suitable IFN inducer. In Vitro IPCA of cryopreserved mononuclear cells (MNC) from peripheral blood of 46 oral cancer patients was studied and was compared to that of healthy, age matched donors. New castle disease virus (NDV) and staphylococcal enterotoxin A (SEA) were used as inducers for evaluating Type alpha IPCA (AIPCA) and Type gamma IPCA (GIPCA) respectively. Age of healthy donors did not influence the AIPCA or GIPCA. Oral cancer patients demonstrated significant low AIPCA (P less than 0.05) (Range Healthy donors 3.5 to 4.6 log 10Iu/ml Oral Cancer 2.0 to 4.6 log 10Iu/ml GIPCA was found to be further depressed (P less than 0.005) (Range Healthy donors 2.87 to 3.6 Log 10 U/ml, Oral cancer 1.7 to 3.6 log 10 U/ml. The depression in IPCA was found to be more pronounced in advanced stage of disease.

Adult↗
PubMed1988

Epitope mapping of Japanese encephalitis virus envelope protein using monoclonal antibodies against an Indian strain.

A panel of monoclonal antibodies (MAbs) raised against an Indian strain of Japanese encephalitis (JE) virus was used to map topographically the epitopes on the envelope protein. Two separate clusters of epitopes were revealed. On the basis of reactivity in haemagglutination inhibition (HI), neutralization (NT), passive protection and antibody-dependent plaque enhancement (ADPE) assays with the MAbs, five functional domains (A, B, C, D and E) were delineated. The flavivirus cross-reactive domain for HI (A) was distinct. The JE virus-specific domain for HI (B) was in continuum with those domains representing non-HI JE virus-specific MAbs (C) and flavivirus cross-reactive MAbs (D). Domain E, which mapped close to domain D was represented by two MAbs that reacted with both JE virus and uninfected cell nuclei. Four conclusions can be drawn. (i) Two distinct antigenic domains were associated with HI, (ii) HI and NT in vivo and in vitro were dissociated functions, (iii) ADPE activity was solely linked with the A domain and (iv) all MAbs reacting with epitopes in the B domain had HI/NT/protective activity but failed to show ADPE. The B domain might therefore be considered the most suitable for development of synthetic or genetically engineered vaccines.

Antibodies, Monoclonal↗
PubMed1987

Replication of Japanese encephalitis virus in monkey, pig and chick leucocyte cultures.

Japanese encephalitis (JE) virus replicated in monkey, pig and day-old chick leucocyte cultures. The titres obtained on days 3 to 5 after infection in monkey, pig and chick leucocyte cultures were comparable. Treatment of monkey leucocyte cultures with the mitogens phytohaemagglutinin P, pokeweed mitogen (PWM), formalinized Staphylococcus aureus (Cowan I) or concanavalin A and pig leucocytes with PWM did not significantly affect their ability to support replication of JE virus. No relationship was observed between the amount of [3H]thymidine incorporated in untreated or mitogen treated monkey or pig leucocyte cultures and the titres of JE virus in such cultures. The ability of monkey, pig and chick leucocyte cultures to support JE virus replication was abrogated following silica treatment. These findings suggest that monocytes may serve as one of the important sites of JE virus replication.

Animals↗
PubMed1987

Regulation of cell-mediated immunity in mice immunised with Salmonella enteritidis.

The effects of diverse factors, such as route of immunisation, composition of immunogen and administration of interferon inducer, on the expression of cell-mediated immune responses against Salmonella enteritidis were investigated in BALB/c and Swiss white mice. Immunisation with live cells of S. enteritidis by the intraperitoneal route (ip) generated both delayed type hypersensitivity (DTH) and protective cell-mediated immunity (CMI). However, the two responses showed diametrically opposite time kinetics. The decline and disappearance by 9 weeks after ip immunisation of DTH and the rise of protective immunity in the same period suggested the possibility that the two responses were mediated by different subsets of T cells. Immunisation by the intradermal (id) route with a sonicate of S. enteritidis generated only DTH; id immunisation also suppressed the development of the protective response following ip immunisation with live S. enteritidis. Both responses were not seen when T cells were eliminated with anti-T cell serum. Oral immunisation with live cells of S. enteritidis induced excellent CMI expressing both DTH and protective responses. On the other hand, oral immunisation with the sonicate of S. enteritidis not only did not induce CMI, but also prevented the development of the DTH and protective response to ip immunisation with live S. enteritidis. Induction of interferon by the administration of poly I: poly C for four consecutive days after id immunisation with killed S. enteritidis suppressed the generation of DTH.

Animals↗