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Biomedical subjects

P Seth

Publications and source records attributed to P Seth.

At least 217 records · Page 12Linked to original sources
PubMed1980

Comparison of indirect hemagglutination and 51chromium release tests for detection of Herpes Simplex Virus type 1 and 2 antibodies in patients with recurrent Herpes infections.

Indirect hemagglutination and 51Cr release tests (IHAT and 51-CRT respectively) were compared in patients with recurrent herpes simplex virus (HSV) infections from whom HSV-1 or HSV-2 was isolated. Both tests were equally sensitive and specific in detecting HSV antibodies. However, IHAT was more specific in detecting homologous HSV antibody response in patients with recurrent HSV-2 infections. Past infections with HSV-1 in the patients with dual infections were detected by determining HSV-type specific antibodies by inhibition of IHAT. Cross absorption studies showed that the antibody reactivity measured by the two tests was qualitatively and quantitatively different. Nevertheless, IHAT has been found to be more appropriate test for seroepidemiologic studies of HSV-2 infections because of its specificity, rapidity and less cost, whereas, 51-CRT appears to measure antibodies against recent and more predominant type of infecting HSV.

Antibodies, Viral↗
PubMed1980

Immune response in rabbits to surface components of extracellular and intracellular forms of vaccinia virus.

The development of cellular as well as humoral immune response to extracellular and intracellular forms of vaccinia virus (ECV and ICV, respectively) and their surface antigens were studied in rabbits. Direct lymphocyte cytotoxicity and peripheral blood leukocyte migration inhibition tests were used to measure cell-mediated immune response, while neutralizing and hemagglutination-inhibiting antibodies were assayed for measuring humoral immune response. Direct cytotoxicity of lymphocytes from rabbits immunized with ECV or its surface proteins was demonstrable by day 7 after immunization, and by the end of week 3 it almost declined to pre-immunization levels. Inoculation with ICV or its surface proteins failed to induce lymphocyte cytotoxicity. In contrast, migration inhibition of peripheral blood leukocytes from rabbits immunized with ECV, ICV, or their surface proteins was observed with homologous antigens. However, leukocytes from rabbits immunized with ECV or its surface proteins also showed migration inhibition in the presence of ICV. Similarly, in the humoral immune response, neutralizing antibodies were produced against homologous as well as heterologous forms of virus despite immunization with purified preparations of ECV, ICV, or their surface proteins. Adsorption with purified ICV preparations abolished the neutralizing activity of these antisera against heterologous forms of virus. Hemagglutination-inhibiting antibodies, on the other hand, were produced only after immunization with ECV or its surface proteins. In addition, antibody-dependent cell-mediated cytotoxicity was employed to detect specific antibody response after immunization of rabbits with live virus, ECV, and ICV. Antisera raised against ECV or live virus supported antibody-dependent cell-mediated cytotoxicity, whereas ICV-antiserum failed to do so. The antibody activity present in the former antisera was abolished by absorption with cell membranes from vaccinia-infected cells but not with purified ICV. The data suggest that immunization with inactivated ECV seems to bring about interaction between host immune response (cellular and humoral) and virus-infected cells, which may, perhaps, be necessary for protection against pox virus infection. A similar interaction is unlikely to occur after immunization with inactivated ICV.

Animals↗
PubMed1979

Evaluation of indirect hemagglutination and its inhibition in the differentiation between antibodies to herpes simplex virus types 1 and 2 for seroepidemiologic studies: use of a II/I index threshold of 85 and an assay of type-specific antibodies.

Two parameters, a II/I index threshold value of 85 and an assay of type-specific antibodies to herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), were assessed, for seroepidemiologic purposes, for their efficacy in the establishment of past infections with HSV-1 and HSV-2 as indicated by the results of tests for indirect hemagglutination and its inhibition. Neither criterion alone established past infection with either HSV-1 or HSV-2. However, by combination of the two parameters, antibodies to HSV-1 and HSV-2 could be differentiated for seroepidemiologic studies.

Adolescent↗
PubMed1979

Use of the 51chromium release test to demonstrate antigenic differences between extracellular and intracellular forms of vaccinia virus.

Complement-dependent antibody lysis of vaccinia-infected cells was examined to demonstrate the antigenic differences between extracellular (ECV) and intracellular (ICV) forms of vaccinia virus. Cytolytic antibodies present in the antisera raised against ECV or live virus (LV) were completely removed by absorption with infected cell membranes or purified ECV but not with purified ICV. Absorption with infected cell membranes also abolished the neutralizing activity of ECV and LV antisera against ECV. On the other hand, antiserum against ICV did not contain cytolytic antibodies against vaccinia-infected cells, even though its neutralizing antibody titre against ICV was high. Moreover, both ECV and ICV antisera neutralized a small proportion of the heterologous form of virus, despite using purified preparations of ECV and ICV, respectively, for raising these antisera in rabbits. In contrast, the 51Cr release test only detected the antibodies against ECV and thus can be used to differentiate between the antibody activity of a serum against ECV and ICV.

Animals↗
PubMed1979

Circulating immune complexes in carcinoma of uterine cervix.

Circulating immune complexes were determined in the sera of forty-eight patients wital status by inhibition of rheumatoid factor (RF) maediated agglutination of IgG coated latex particles. The inhibitory activity was present in 63% of the sera from cervical cancer patients but only 13% of sera from control women contained this activity. Similarly, anticomplementary activity suggestive of the presence of immune complexes was present in 71% of sera from cancer patients and 13% of sera from control women. The incidence as well as the levels of immune complexes (IC) were higher in sera of patients with advanced stages of cancer as compared to those with Stage I cervical cancer. In addition, 95% of sera from cervical cancer patients had cryoblobulins, whereas only 20.8% sera from matched controls were positive for cryoprecipitates. All the cryoglobulins contained IgG type of immunoglobulin except one which had IgA immunoglobulins also. The complexes have not been characterized with regard to the nature of the antigen(s) present.

Antigen-Antibody Complex↗
PubMed1978

Antibodies to Herpes simplex virus types 1 and 2 in patients with squamous-cell carcinoma of uterine cervix in India.

Antibody activity to Herpes simplex virus type-1 (HSV-1) and type-2 (HSV-2) was measured by the indirect hemagglutination (IHA) test in sera from 124 women with squamous-cell carcinoma of the uterine cervix, 46 women with non-cervical cancer and 116 matched normal women. The type-specific antibodies were assayed by IHA inhibition test. The proportion of cervical cancer cases positive for HSV-2 infection was significantly greater than that of non-cervical cancer cases and matched control women. No difference was observed in the percentages positive for HSV-1 infection among the three study groups. The mean titers of antibodies to HSV-1 as well as HSV-2 were significantly higher than the respective titers in the other two study groups. However, determination of type-specific antibodies did not help in establishing evidence for past infection by HSV-2 in patients with cervical cancer, as no type-specific HSV-2 antibodies were produced in 58% of the cases. The cervical cancer cases were also analysed according to clinical staging (Stages 0 to IV) and histological differentiation of squamous-cell carcinoma. Neither the percentage of positives for HSV-2 infection nor HSV-antibody titers varied, either in clinical staging or in histological differentiation of cervical cancer. These findings suggest that HSV-2 may be related to cervical cancer as an etiological agent but not as a passenger virus of carcinomatous tissue.

Adult↗
PubMed1976

Quantitation of antibodies to Herpes simplex virus types 1 and 2 by complement-dependent antibody lysis of infected cells.

The release of 51Cr from cells infected with herpes simplex virus type 1 or type 2 by antibody and complement was examined as a method of quantitating antibodies to the viruses. With decreasing concentration of antibody, a typical dose-response curve was observed; a region of antibody excess in which dilution did not affect percentage of specific 51Cr release followed by a region in which a linear relation existed between dilution and percentage of specific 51Cr release. Therefore, a quantitative expression of antibody titer was defined as that dilution of serum which yielded 50% specific 51Cr release. The slopes of the linear portion of the dose-response curves were characteristic of the type of virus used to infect the cells and not upon the source of antiserum, thus, the slopes could be used to estimate antibody titers. The multiplicity of infection influenced the antibody titers; reproducible results were obtained when cultures were infected with 3 to 5 plaque-forming units per cell; the antibody titers decreased when less virus was used. The antibody titers obtained by the 51Cr release test were similar to those obtained by a microneutralization test. The 51Cr release test was found to be reproducible and to be useful in estimating the percentages of antibody activity attributable to antibodies to cross-reacting and type-specific antigens.

Antibodies, Viral↗
PubMed1976

Relative concentrations in human sera of antibodies to cross-reacting and specific antigens of Herpes simplex virus types 1 and 2.

The relative concentrations of antibodies to the cross-reacting and type-specific antigens of herpes simplex virus types 1 and 2 were examined in sera from patients who had been infected by type 1 virus only, by type 2 virus only or by both viruses. Complement-dependent lysis of 51Cr-labeled cells was used to measure antibodies to the surface antigens of cells infected by the viruses. Approximately 80% of the antibody activity was attributable to cross-reacting antigens and 20% to type-specific antigens in sera from patients infected with either type 1 or type 2 virus. Among patients infected with type 1 virus and then type 2 virus, approximately 90% of the antibody activity was to the cross-reacting antigens, 5 to 10% to type 1-specific antigens and little or no antibody to type 2-specific antigens. The observations suggest that infection by type 2 virus in patients with a prior type 1 infection results in an antibody response to the cross-reacting antigens with little or no response to the type-specific antigens.

Antibodies, Heterophile↗
PubMed1976

Neuraminidase reversal of resistance to lysis of herpes simplex virus-infected cells by antibody and complement.

The susceptibility to lysis by antibody and complement was examined in four human cell lines. The cells were infected with herpes simplex virus type 1 and lysis was assessed by the 51Cr release test by using antibodies to herpes simplex virus and guinea pig serum as a source of complement. The four cell lines were found to differ in their susceptibility to lysis, although virus replication was readily demonstrated in the different cell lines. By indirect immunofluorescence, no differences in the expression of virus antigens at the surface of the cells could be found between the different cell lines. Treatment of cells with neuraminidase markedly enhanced the sensitivity of the cells which were relatively insensitive to lysis. The enhancement of susceptibiltiy to lysis by neuraminidase occurred if cells were treated before reaction of the cells with antibody and if the cells were reacted with antibody before treatment with the enzyme. No enhancement was observed when cells were reacted with antibody and complement before neuraminidase treatment. Neuraminidase treatment did not seem to enhance appreciably the quantity of antibody which reacted at the cell surface. The observations suggest that surface properties of certain cells render the cells resistant to lysis by antibody and complement and that the resistance to lysis can be abrogated by treating the cells with neuraminidase.

Antibodies, Viral↗
PubMed1976

Serological and epidemiological considerations of the role of herpes simplex virus type 2 in cervical cancer.

To assess the possible biological significance of the observations that women with cervical cancer tend to be younger at first intercourse than control women, data from 1823 women were analyzed for the relationship between age at 1st intercourse and number of sex partners. Women who were younger at first intercourse had more sex partners than did women who were older at first intercourse. The interdependence of age at first intercourse and number of sex partners does not exlude the possibility that intercourse at an early age represents a biologically significant event in which the neoplastic process is initiated. However, it is equally possible that younger women at first intercourse may have multiple sex partners and be at greater risk of coming in contact with a putative oncogenic agent later in life. In addition, sera from patients with herpesvirus infections were assayed for cross-reacting and type-specific antibodies. Approximately 80% of the total antibody activity was to the cross-reacting antigen and only 20% was to the type-specific antigens in the sera of patients infected with either type 1 or type 2 virus. Among patients infected with both types of virus, less antibody activity to the type-specific antigens and more antibody activity to the cross-reacting antigens were found. These observations are discussed with respect to case-control seroepidemiological studies.

Age Factors↗