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.

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.

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.

Xenogenic transfer of human lymphocytes in tolerized mice

Female nu/+ or BALB/c mice were immunized with human peripheral blood lymphocytes (PBL) before and during pregnancy. Pups born to these mothers were inoculated with human PBL or human fetal bone marrow and thymus cells. Tolerization of the pups to human PBL was observed without graft-versus-host reaction. Presence of human immunoglobulins was observed in the pups for 3-4 weeks. Human T cells also could be detected for a period of 3-4 months in these mice.

Rhesus monkeys infected with hepatitis E virus (HEV) from the former USSR are immune to subsequent challenge with an Indian strain of HEV

Two rhesus monkeys (M. mullata) of approximately two years of age were inoculated intravenously with a 10% suspension of hepatitis E virus (HEV) positive stool from Kirghistan as evidenced by immuno-electron microscopy. Evidence of HEV infection was demonstrated by rise in serum alanine transaminase (ALT) levels and seroconversion of these monkeys to anti-HEV after 1-1/2 months post-inoculation as evidenced by immunoblot. One year after the primary inoculation, these monkeys were challenged with an Indian strain of HEV. No rise in serum ALT levels was noted during an observation period of 6 months. The same inoculum produced HE in two rhesus monkeys. The results showed that strains from India and Kirghistan were antigenically closely related and rhesus monkeys infected with one strain of virus were immune to another strain.

Analysis of computer-predicted antibody inducing epitope on Japanese encephalitis virus

Theoretical methods to delineate antibody inducing epitopes have been employed to predict antigenic determinants on envelope glycoprotein (gpE) of Japanese encephalitis (JE), West Nile (WN) and Dengue (DEN) I-IV viruses. A predicted region on JE virus gpE 74CPTTGEAHNEKRAD87 was synthesized, conjugated to KLH (KLH-peptide) and used in immunization of mice. A mouse monoclonal antibody (MoAb IVB4) reactive to the peptide was also found to react with native JE virus gpE. Characterization of the idiotypic (ID) determinants with the help of polyclonal domain-specific anti-ID antibodies revealed that polyclonal anti-KLH-peptide antibodies and MoAb IVB4 are flavivirus-cross-reactive to Hx and NHx domains, respectively. The region 74-87 in JE virus gpE has been mapped as a linking area between Hx and NHx domains. Reactivity of the peptide with sera from JE patients and vaccinees also indicated the feasibility of using predicted peptides for diagnostic and prophylastic purposes.

Practices of preparation of oral rehydration solution among mothers reporting to the drug distribution centres in Delhi, India, 1992

A study to assess the ability for preparing oral rehydration solution (ORS) correctly among the recipients of ORS packets from the Government of India service outlets was carried out in Delhi during July to August, 1992. One centre from each of the municipal zones of Delhi was selected randomly. Four hundred mothers with a child having diarrhoea reporting to the nearest centre were studied using a standardized questionnaire adopted from the WHO household survey schedule. Two paramedical personnel from each of the centres who were responsible for distribution of ORS were also interviewed regarding their knowledge of preparation of ORS. Results indicate that only 10.8% of mothers prepared the ORS correctly and that the majority (83%) of the paramedicals involved in ORS distribution had correct knowledge about its preparation. Communication methods directed at the mothers regarding the preparation of ORS should be stepped up in these communities.

Dengue in Gujarat state, India during 1988 & 1989

Following the reports of epidemics of febrile illness from several rural and urban areas of Gujarat state (India) in 1988, epidemiological investigations were carried out and dengue (DEN) virus activity was demonstrated in large cities such as Surat and Rajkot as well as several villages in Sabarkantha district. Two strains of dengue type-2 each were isolated from human sera from Surat city and a village in Sabarkantha district. Six strains of dengue virus were isolated from Aedes aegypti mosquitoes collected at Chotasan village, two of which were confirmed as DEN type-2. Of the 560 patients' sera tested from different areas (including villages and townships), 122 showed evidence of dengue infection and another 236 showed a broader reaction with flaviviruses. Entomological investigations showed a widespread distribution of Ae. aegypti both in urban and rural areas. In the household conditions this mosquito was found to breed predominantly in containers with non-potable water. Amongst these, cement containers manufactured in towns and distributed to the villages seem to play an important role in the spread of this species. In non-residential areas prolific breeding of Ae. aegypti was observed in automobile tyre dumps, and varied types of scrap, in towns and villages. Distribution and relative prevalence of the species were studied in 46 towns and villages, covering the spectrum of rural-urban-continuum. These studies provide an indication regarding the mechanism of the spread of DEN virus through peoples' movement, transport, the process of urbanisation etc.

Human immunodeficiency virus-1 infection in spouses of seropositive individuals

BACKGROUND

Unprotected sex can lead to transmission of the human immunodeficiency virus-1 (HIV-1) to the spouse of an infected individual. We studied the incidence of HIV-1 infection in the spouses of cases diagnosed to have HIV-1 infection by serology and the polymerase chain reaction (PCR).

METHODS

Blood samples collected from 9 index cases and their respective spouses were tested for HIV-1 infection by ELISA, Western blot (WB) and PCR as well as from 10 healthy individuals with no high-risk behaviour. DNA extracted from both plasma and peripheral blood mononuclear cells was amplified by PCR, using multiple primer pairs for distinct regions of the HIV-1 genome. Specificity of the PCR product was demonstrated by hybridization to an oligonucleotide probe.

RESULTS

All the index cases which were seropositive by ELISA and WB were also positive by PCR of plasma extracted DNA. Eight of the spouses were seronegative. Of these seven were positive by PCR--one spouse was negative by ELISA but showed a p55 band on WB and was positive by PCR. One spouse was negative by serology and PCR. The spouse belonging to the lone concordant couple was positive by serology and PCR. Except for one index case, PCR signals were obtainable only from DNA extracted from plasma but not from the DNA extracted from peripheral blood mononuclear cells. The control samples were negative by serology and PCR.

CONCLUSION

It is possible to detect HIV-1 infection by PCR using DNA extracted from plasma even when the individuals are negative by ELISA and WB. It can help in the early counselling of HIV infected persons and their spouses.

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.

An investigation of an outbreak of viral hepatitis in a residential area of Delhi

Epidemiological investigation of a focal outbreak of jaundice in the KD block of Pitampura, Delhi during February-March 1992 revealed that 7.0 per cent of the population of the block suffered from viral hepatitis. There was no age or sex predilection. Epidemiological findings and Serological studies suggest that the epidemic was due to Hepatitis E (Enterically transmitted Non A and Non B) virus.

Epidemiological features of cholera outbreak in Delhi in 1988

During 1988 a large scale outbreak of cholera occurred in Delhi giving rise to a total of 1708 bacteriologically proved El Tor cholera cases, the highest number recorded in a single year in Delhi, following its first detection in 1965. Civil lines and Shahdara zones were the worst affected areas recording 85.7 and 55.7 cases per 100,000 population respectively. The highest incidence rate was observed in the age group of 1-4 years (77 per 100,000). Males and females were equally affected. The data of moving average show the endemicity of cholera in Delhi with an increasing trend. The risk factors identified are lower socioeconomic status, poor personal hygiene, drinking water and food storage practices.

Insecticide susceptibility status of certain populations of Aedes aegypti mosquito from rural areas of Maharashtra state

Ae. aegypti mosquitoes from rural areas of Maharashtra state were subjected to insecticide bio-assays. All the populations showed resistance to DDT at larval and adult stages. No resistance to deltamithrin and malathion was detected at any stage. Biochemical analysis of these mosquito populations showed that resistance to DDT was probably due to increase in the kinetics of glutathione S-transferase.

Immunofluorescence studies on the replication of some arboviruses in nucleated and enucleated cells

Porcine stable kidney (PS) or Vero cells infected with either flavi-(Japanese encephalitis--JE, West Nile--WN, and Dengue--DEN-2) or alphaviruses (Chikungunya--CHIK and Sindbis--SIN) were stained in indirect fluorescent antibody (FA) assay with anti-JE virus monoclonal (MoAb) Hx-3 (flavivirus cross-reactive) and polyclonal (immune PF) antibodies. By 48 hr post infection (p.i.), 15 to 20% of the three flaviviruses and CHIK virus infected cells, which revealed positive cytoplasmic immunofluorescence (IF), showed intranuclear IF. By 24 hr p.i., the intranuclear IF was not observed or became diminished. The enucleation of cells by cytochalasin B treatment prior to the infection with any of the three flaviviruses resulted in the loss of IF compared with the cells enucleated after the infection (18 hr p.i.) whereas SIN or CHIK virus-infected cells reacted similarly by the either method. These findings indicate an essential role of the nucleus in the replication of the flaviviruses only and while replicating in the infected cells, flaviviruses and CHIK virus might express viral specific proteins in the cell nuclei.

Hepatitis E virus infection in pregnant rhesus monkeys

Ten non-pregnant female monkeys and four pregnant monkeys (all Macaca mulatta) in the last third of their gestation period were infected intravenously with the stool sample of a patient with hepatitis E virus infection (immuno-electronmicroscopy positive for hepatitis E virus). Four more non-pregnant monkeys were inoculated with a lower dose (less number of virus particles by IEM) of a stool sample collected on a different day from the same patient. The average incubation period as evidenced by the rise of serum alanine transferase in the non-pregnant monkeys, was 36.4 +/- 4.9 days. The dose of the virus did not affect the incubation period. Two of the pregnant monkeys had incubation periods of 9 and 13 days respectively. They delivered healthy babies on 40th and 53rd day respectively after inoculation. At the age of 11 months, both babies were negative for anti-HEV antibodies. One monkey which delivered a healthy baby on the 2nd day after inoculation had incubation period of 36 days. The baby of this monkey was anti-HEV positive at the age of 11 months. The incubation period was 41 days in the fourth monkey which delivered a macerated foetus on the 36th day after infection. No fatality was recorded in the infected monkeys. Bile samples collected from all monkeys showed strong signals in nested polymerase chain reaction (PCR). It seems that the incubation period in pregnant monkeys was determined by the state of pregnancy.

Influenza surveillance in Pune, India, 1978-90

Continuous surveillance of influenza was carried out in Pune between 1978 and 1990. Most of the cases were identified during investigation of 16 outbreaks of influenza in Pune over this period. The majority of cases were children. Ten of the outbreaks occurred during rainy seasons. A total of 290 isolates consisting of several antigenic variants of influenza type A (H3N2), type A (H1N1), and type B viruses were isolated from throat/nasal swabs that were processed in chick embryos and MDCK cell culture and identified using the haemagglutination inhibition test. These variants circulated every year or in alternate years. Nearly two-thirds of the influenza virus isolates (181 out of 290) were from children aged < 10 years. Seasonal analysis indicated that the highest number of isolates (174) were collected during the rainy months of July, August and September, with the maximum number (93) in July.

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.

Insecticide susceptibility status & enzyme profile of Aedes albopictus populations from different localities of Maharashtra state

Susceptibility status of five populations of Ae. albopictus mosquitoes from Maharashtra state, to DDT, malathion, fenitrothion, bromophos, propoxur and deltamethrin was studied and compared with the laboratory population. Four populations survived when adults were exposed to 4 per cent DDT impregnated paper for 2 h; though three of these populations had lower DDT-LC50 values at larval stages in comparison with the laboratory population. Results of topical application of DDT on these four populations supported these findings by showing comparatively higher LD50 values at adult stages in comparison with the laboratory population. All the populations were highly susceptible to other pesticides tested i.e., malathion, fenitrothion, bromophos, propoxur and deltamethrin. These populations were distinguished from each other by esterase isoenzyme patterns.

Identification and characterization of mutations in 'X' region of a hepatitis B virus carrier

A defective form of Hepatitis B virus (HBV) was identified in an apparently healthy voluntary blood donor, who was positive for the presence of HBV by dot blot hybridization, but did not have any serological markers of HBV infection. Two regions, part of X and part of surface antigen genes, were amplified by polymerase chain reaction, cloned and sequenced by Sanger's dideoxy chain termination method. The base sequence analysis revealed that the HBV mutant belonged to ayw serotype and showed three point mutations, in the form of deletions at nucleotides number 1402, 1438 and 1450. Such mutations in the 'X' region, and their likely presence elsewhere, could explain altered antigenic expression.

HIV-2 antibodies in serum samples from Maharashtra state

Two hundred serum samples were tested to detect the presence of HIV-2 infection in Maharashtra state. The serum samples were derived from various groups including those with high risk behaviour for HIV infection. All samples were tested by three combined HIV-1 and HIV-2 ELISA kits. The reactivity was confirmed by LiaTek HIV 1+2 immunoblot. The study confirmed that HIV-2 infection exists in Maharashtra, as 14 samples showed antibodies to HIV-2 and 14 showed antibodies to both HIV-1 and HIV-2. Antibodies to HIV-2 or HIV-1 and HIV-2 were detected mainly in persons with high risk behaviour.