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Biomedical subjects

K Banerjee

Publications and source records attributed to K Banerjee.

At least 91 records · Page 5Linked to original sources
PubMed1995

Growth and cytopathic effect of Japanese encephalitis virus in astrocyte-enriched cell cultures from neonatal mouse brains.

Neuron-free, astrocyte-enriched brain cell cultures from newborn mice could be infected with Japanese encephalitis virus (JEV) as evidenced by immunofluorescence (IF), viral replication and cytopathic effect (CPE). Virus-specific cytoplasmic fluorescence was detectable in astrocytes first after 18 hrs, released infectious progeny virus in the culture fluid after 24 hrs, and CPE after 11 days post infection (p.i.).

Animals↗
PubMed1994

Seroepidemiology of water-borne hepatitis in India and evidence for a third enterically-transmitted hepatitis agent.

Many epidemics of water-borne hepatitis have occurred throughout India. These were thought to be epidemics of hepatitis A until 1980, when evidence for an enterically transmitted non-A, non-B hepatitis was first reported. Subsequently, hepatitis E virus was discovered and most recent epidemics of enterically transmitted non-A, non-B hepatitis have been attributed to hepatitis E virus infection. However, only a limited number of cases have been confirmed by immuno electron microscopy, polymerase chain reaction, or seroconversion. In the present study we have performed a retrospective seroepidemiologic study of 17 epidemics of water-borne hepatitis in India. We have confirmed that 16 of the 17 epidemics were caused at least in part by serologically closely related hepatitis E viruses. However, one epidemic, in the Andaman Islands, and possibly a significant minority of cases in other epidemics, appears to have been caused by a previously unrecognized hepatitis agent.

Adolescent↗
PubMed1994

C3b receptor (CR1) genomic polymorphism in rheumatoid arthritis. Low receptor levels on erythrocytes are an acquired phenomenon.

The number of complement receptor 1 (CR1, CD35) molecules on erythrocytes is genetically determined by two codominant alleles. The numerical expression of CR1 on erythrocytes correlates with a HindIII-RFLP or CR1 gene using CR1-1, a complementary DNA probe. We have found low CR1 on erythrocytes in patients with rheumatoid arthritis (RA) in an Indian population. Low levels in RA patients may be acquired or genetically determined. Fifty-two patients with RA, 48 nonrelated healthy subjects and 19 consanguineous relatives of patients were genotyped. CR1 numbers on erythrocytes were quantitated by the enzyme-linked immunosorbent assay using monoclonal anti-CR1 antibody. Normal subjects and patients were followed up for a period of 6 months to evaluate the stability of their CR1 expression. The gene frequency for allele H and L (7.4- and 6.9-kb HindIII restriction fragment, respectively), which correlated with high and low expression of CR1 on erythrocytes was 0.77 and 0.23 in the normal controls. Gene frequency in RA patients was 0.78 and 0.22 for H and L allele, which did not differ significantly from either controls or relatives (0.80 and 0.20 for H and L allele, respectively). However, RA patients expressed fewer CR1 on erythrocytes within each genotype than their relatives and controls. CR1 on erythrocytes were found to be stable in consecutive samples in controls. In RA patients, the number varied between low and high during the course of the disease. The variation in number was significantly correlated (p < 0.05, r = -0.85 to -0.98) with disease activity as monitored by erythrocyte sedimentation rate. Our results suggest that low levels of CR1 on erythrocytes in patients with RA are not inherited, rather they are acquired during the course of the disease.

Adolescent↗
PubMed1994

Detection and cloning of potent transforming gene(s) from chewing tobacco-related human oral carcinomas.

High molecular weight DNA isolated from 14 primary tumour tissues of human oral carcinoma patients was analysed for transforming activity by NIH3T3 co-transfection assay using pSV2neo gene as a selectable marker, followed by nude mouse tumorigenicity assay. Ten of the patient tumour tissues demonstrated molecular lesions in myc, ras or/and EGF-R genes, whereas 4 patients did not show tumour associated aberrations in these oncogenes. The G418-resistant transfected cells from 12 of 14 individual patients demonstrated transforming potential by colony formation in soft agar and tumour induction in nude mice within 25-80 days. DNAs from the transfected cells, consequent nude mice tumours and corresponding cell lines, contained human Alu sequences. Southern blot hybridisation with ras, myc, EGF-R oncogenes demonstrated the presence of human H-ras oncogene in one of the 12 sets of nude mice tumours. In contrast, DNA from the other 11 sets of nude mice tumours indicated absence of c-myc, N-myc, L-myc, H-ras, K-ras, N-ras and EGF-R genes on Southern analysis. Further, DNAs from five first cycle tumorigenic transformants were subjected to a second cycle of transfection, and induced tumours in nude mice with a shorter latency period of 21-50 days. The secondary transformants contained discrete human Alu sequences; however, the DNA did not hybridise with myc/ras/EGF-R probes. A genomic library was constructed from a second cycle nude mice tumour, using EMBL-3 as the vector. Four human Alu sequence positive clones were isolated on screening 2 x 10(5) plaques, and one of the recombinant clones subjected to fine restriction mapping using 16 restriction enzymes. The lack of association of the nude mice tumour DNA with myc/ras/EGF-R showing aberrations in the primary human tumour, implies activation of an alternative potent transforming gene(s) in the chewing tobacco-related oral carcinomas in India.

3T3 Cells↗
PubMed1994

Antibodies against hepatitis E virus in Old World monkeys.

To examine whether Indian monkeys are infected with hepatitis E virus (HEV) in nature, serum samples from wild rhesus (Macaca mullata), bonnet (M. radiata) and langur (Presbytes entellus) monkeys were screened for anti-HEV IgG antibodies in recombinant antigen-based ELISA assays. The positivity rates were 36.7%, 19.1% and 2% respectively. The protection of such antibodies against human HEV was studied in four rhesus monkeys. Of the two rhesus monkeys with anti-HEV titres of 100 and 1000 respectively which were inoculated with the KOL-91 strain of HEV, the former demonstrated a 10-fold rise in anti-HEV titres. Anti-HEV titre in the second rhesus monkey remained unchanged. Neither of the monkeys showed any rise in serum alanine transaminase (ALT) or presence of virus in the faeces, as tested by polymerase chain reaction (PCR). Two other rhesus monkeys with anti-HEV titres of 10,000 and 100 respectively were inoculated with the AKL-90 strain of HEV. Serum ALT levels and anti-HEV titres remained unchanged in the first monkey. Excretion of virus in faeces was not noted (PCR). The second monkey developed a typical HEV infection. HEV infection could be produced in anti-HEV negative control monkeys inoculated with both strains of HEV. These results show that either human or simian HEV, or a closely related agent, is circulating among Indian macaques. Titre-dependent protection of naturally occurring anti-HEV antibodies supports this view.

Alanine Transaminase↗
PubMed1994

Inheritance of oral susceptibility of Aedes aegypti to Chikungunya virus.

A colony of rosy eye mutants of Aedes aegypti was established. This strain was refractory to Chikungunya virus by oral route of infection when compared with the wild-type parent strain. The refractoriness of this strain seems to be due to a mesentronal barrier, since both the mosquito strains supported the multiplication of virus after intrathoracic inoculation. The rosy eye strain was also found to be refractory to Sagiyama virus (Alphaviridae: Getah virus subtype) when compared with wild-type parent strain, but no such difference in the oral susceptibility was found with dengue-2 (Flaviviridae) virus. The rosy eye mutant appears to be closely linked to the gene(s) for refractoriness to alpha viruses and may be useful in future studies in understanding the genetic basis of vector competence of Ae. aegypti to arboviruses.

Aedes↗
PubMed1994

Effect of sublethal dosages of insecticides on chikungunya virus susceptible and refractory strains of Aedes aegypti.

Three strains of Aedes aegypti mosquitos viz (i) CRS, refractory to Chikungunya (CHIK) virus by oral route of infection but susceptible to DDT (2) CSS, susceptible to CHIK virus and also susceptible to DDT (3) CSS-DDTR, susceptible to CHIK virus but resistant to DDT, were examined for the effect of sublethal dosages of DDT and deltamethrin on their fecundity. Biochemical analysis showed that there was an increase in glutathione s-transferase activity in the CSS-DDTR strain which was associated with DDT resistance. There was an increase in acetylcholinesterase activity in the CRS strain, however it was not associated with resistance to all the three insecticides tested. No significant differences in the fecundity of these three strains were observed, though there was some increase in the number of non layers in CSS-DDTR strain after the treatment of DDT and mean number of eggs laid by CSS and CRS strains was slightly reduced (0.5 > p < 0.1) after the treatment with deltamethrin.

Acetylcholinesterase↗
PubMed1994

Experimental studies on the susceptibility of domestic pigs to West Nile virus followed by Japanese encephalitis virus infection and vice versa.

A study on the susceptibility of domestic pigs to West Nile virus (WNV) and Japanese encephalitis virus (JEV) infection was carried out. One batch of pigs was inoculated with WNV followed by JEV and another batch was inoculated vice versa. The first batch developed low level of viraemia and haemagglutination-inhibition (HI) antibodies to both viruses. There was a booster effect on the already existing WNV antibodies after challenging with JEV. In the second batch the animals developed high level of JE viraemia but did not develop WN viraemia. They developed HI antibodies to both JEV and WNV with low booster effect of WNV infection on JEV antibodies. Fresh batches of pigs were infected through bite of WNV- and JEV-infected Culex vishnui mosquitoes. WNV-infected pigs did not show viraemia, whereas JEV-infected ones developed JE viraemia. The study indicated that pigs were poor hosts for WNV but good ones for JEV. However, WNV antibodies reduced the level of JE viraemia and JEV infection boosted the already existing WNV antibodies.

Animals↗
PubMed1994

Measles outbreak in a tribal population of Thane district, Maharashtra.

In March 1992, an outbreak of measles, in the tribal population of Vavar village, Mokhada Taluk, Thane district, Maharashtra, was investigated. Two hamlets of Vavar village namely Sagpanipada (epidemic in October, November 1991) and Behedpada (epidemic in January, February 1992) were affected. In both hamlets, measles cases were confined to children below 10 yrs and 96% of the cases occurred in children below 6 yrs. Attack rates were 52.7% and 51.4% and case fatality rates were 31.2% and 15.6% at Sagpanipada and Behedpada, respectively. All the convalescent patients' sera possessed IgM antibodies against measles. A clear drop in IgM and a rise in IgG antibodies against measles was observed in 35 paired samples from convalescent patients. Fifty four per cent of sera from controls, possessed IgM antibodies. Migrating population appeared to have imported measles which flared up in an epidemic among the susceptibles. Priority immunization of the children of remote isolated populations may prevent such epidemics.

Child↗
PubMed1994

Field evaluation of formalin inactivated Kyasanur forest disease virus tissue culture vaccine in three districts of Karnataka state.

A formalin inactivated Kyasanur forest disease (KFD) virus tissue culture vaccine produced by the health department of the State Government of Karnataka at Shimoga was administered in Shimoga, Uttar Kannada and Chikmangalur districts during 1990-92 KFD epidemic seasons. The selection of places for vaccination was based on the prevalence of KFD activity in previous years; villages adjacent to KFD affected areas and the villages from which mortality in monkeys was reported. A total of 284 villages was covered under vaccination; 26850 individuals received one dose whereas, 61302 received two doses of vaccine. No untoward reaction was observed in any of the vaccinees. In the 72 KFD affected villages there were 14 patients among 9072 and 10 among 21083 vaccinees receiving one and two doses respectively, whereas 325 patients were reported among 37373 unvaccinated individuals during the same period. In 1990-91 the number of males patients was more than females whereas, in 1991-92 the ratio was reserved. On analysis indicated that the vaccine has a highly significant protective effect.

Adolescent↗
PubMed1994

Cultivation of buffalo green monkey kidney cells persistently infected with hepatitis A virus.

Studies were carried out to determine the effect of prolongation of incubation periods, cocultivation with normal buffalo green monkey kidney (BGMK) cells and different concentrations of foetal calf serum (FCS) on the production of hepatitis A virus (HAV) by BGMK cell line persistently infected with HAV strain HM175. HAV could be detected from week 1 onwards. However, maintenance of cultures beyond this period was found to yield substantially higher quantities of virus. Cocultivation of persistently infected cells with normal BGMK cells also improved the antigen yields. Different concentrations of FCS did not show any effect on the amount of virus produced. The cell line was maintained up to 46 passages during which there was continuous production of HAV in the cells and release of small amounts of virus in the culture supernatants. Cell associated and cell free viral particles were found to be infectious. Supernatant derived virus was a highly suitable inoculum for infecting other susceptible cell lines. Persistently infected BGMK cell line appears to be a reliable and economical source to derive HAV in adequate amounts for diagnostic and research purposes.

Animals↗
PubMed1994

Indigenous anti-hepatitis A virus IgM capture ELISA for the diagnosis of hepatitis A.

Anti-hepatitis A virus IgM capture ELISA was developed by using the reagents produced in the NIV laboratory. The major reagents of the assay were anti-human IgM antibody, hepatitis A virus (HAV) and anti-HAV IgG-horse radish peroxidase (HRP) conjugate. Of these, anti-human IgM antibodies were generated in rabbit against IgM secreted by human hybridoma clone(G3). HAV was derived from buffalo green money kidney cell line infected with HM-175 strain. Virus purified from the cell lysates was used for immunization of rabbits and guinea-pigs. There was very low anti-HAV response. A seropositive rhesus monkey was inoculated with monkey adapted strain of HAV to boost the anti-HAV antibody titre. Anti-HAV IgGs derived from hyperimmune sera of monkey and hepatitis A patient were conjugated with HRP. The preparations of conjugate--particularly human antibody--HRP conjugate yielded highly satisfactory results in anti-HAV capture ELISA. The assay appears to be specific, sensitive and quick and is useful in differentiating acute HAV infection from other acute infections caused by B, E and non-A non-B hepatitis viruses.

Animals↗
PubMed1993

Aetiology of acute sporadic non-A, non-B viral hepatitis in India.

Non-A, non-B (NANB) hepatitis viruses are now classified as hepatitis E (enterically transmitted) and hepatitis C (parenterally transmitted). India experiences a large number of epidemics of the enteric disease every year. In addition, about 70% of the sporadic cases among adults are also due to NANB hepatitis. With the availability of an immunoblot assay for the detection of anti-HEV-IgM and the polymerase chain reaction (PCR) for the detection of HCV-RNA, serum samples from epidemic and sporadic NANB patients were screened for these markers. We found that a large number of cases from the epidemics were HEV, though a few remained undiagnosed, while of the sporadic cases only a few could be diagnosed as HCV or HEV; a large proportion remained undiagnosed.

Acute Disease↗
PubMed1993

Alternative mode of replication of human immunodeficiency virus: a hypothesis.

For diagnosis of Human Immunodeficiency Virus (HIV) infection by the recently developed Polymerase Chain Reaction (PCR), the two commonly used clinical samples are either the peripheral blood monocytes (PBMC) or the plasma of the infected individuals. In the former instance, DNA is extracted from PBMC. The integrated proviral DNA is then amplified using HIV specific oligonucleotide primers. In the latter instance, RNA is extracted from plasma. This is reverse transcribed in vitro into cDNA by using extraneous reverse transcriptase. This cDNA is then used as a target in PCR experiments with HIV specific primers. In contrast we have recently used DNA directly extracted from plasma of infected individuals. This DNA was used for amplification of HIV genome with primer pairs specific for HIV. An interesting outcome of this study was a model to explain the presence of DNA of HIV in the plasma. We suggest that possibly there is an alternative mode of replication of HIV. Apart from the obligatory integration of the DNA of HIV into the DNA of lymphocytes as provirus, several additional copies of the DNA are also made which remain unintegrated. These probably exist as a housekeeping repertoire of the viral genome. These DNA molecules may be released into the circulation along with the newly formed mature virion particles during the usual course of replication and release of the virus. In our experiments with direct extraction of DNA from plasma, these unintegrated DNA of HIV may act as the target for PCR to give positive signals with HIV specific primers.

DNA, Viral↗