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Biomedical subjects

I K Mushahwar

Publications and source records attributed to I K Mushahwar.

At least 19 recordsLinked to original sources
PubMed1992

Lack of protective immunity against reinfection with hepatitis C virus.

Some individuals infected with hepatitis C virus (HCV) experience multiple episodes of acute hepatitis. It is unclear whether these episodes are due to reinfection with HCV or to reactivation of the original virus infection. Markers of viral replication and host immunity were studied in five chimpanzees sequentially inoculated over a period of 3 years with different HCV strains of proven infectivity. Each rechallenge of a convalescent chimpanzee with the same or a different HCV strain resulted in the reappearance of viremia, which was due to infection with the subsequent challenge virus. The evidence indicates that HCV infection does not elicit protective immunity against reinfection with homologous or heterologous strains, which raises concerns for the development of effective vaccines against HCV.

Acute Disease↗
PubMed1992

Detection of hepatitis C viral RNA by the polymerase chain reaction in serum of patients with post-transfusion non-A, non-B hepatitis.

Serial serum samples from cardiac patients with a history of chronic or resolved post-transfusion non-A, non-B hepatitis were analyzed by a combination of cDNA synthesis and the polymerase chain reaction (cDNA/PCR) to amplify HCV RNA. Analysis of sera drawn after the acute hepatitis episode from 8 of the patients who had an acute, resolving HCV infection showed no detectable levels of HCV RNA when primers from the NS3 region were used. Evaluation of these sera with primers from the 5'-untranslated (5'-UT) region revealed that one patient was positive for HCV RNA. Further analysis of serial serum samples available from two of these patients indicated that a resolved infection was associated with a disappearance of detectable HCV RNA after a peak level during the acute phase of the disease. In contrast, post-acute samples from 4 of 6 patients with symptomatic acute HCV infection evolving to chronicity were positive for HCV RNA using primers from the NS3 region, however, upon retesting with primers from the 5'-UT region, all 6 patients were found to be positive. Analysis of serial serum samples from 2 of these patients showed the persistence of HCV RNA in 70% of the samples. These two patients were subsequently treated with interferon alpha-2b. One patient resolved his disease and normalized his aminotransferase level during treatment and thereafter, while the other relapsed upon cessation of treatment. In these two patients, normalization of ALT levels was consistent with the absence of HCV RNA while relapse of disease was confirmed by the reappearance of detectable levels of HCV RNA. These results indicate the utility of HCV RNA as a marker for persisting HCV viremia and in differentiating patients with ongoing active HCV infection from those with an acute resolving disease.

Acute Disease↗
PubMed1992

Examination of the buoyant density of hepatitis C virus by the polymerase chain reaction.

Sucrose and cesium chloride density gradients were used to fractionate hepatitis C virus (HCV) infectious chimpanzee plasma. The fractionated plasma was then evaluated for HCV RNA sequences using cDNA synthesis and the polymerase chain reaction (cDNA/PCR). cDNA/PCR detectable HCV RNA was identified repeatedly in two regions. One region was at the top of the gradients with a buoyant density of < or = 1.03 g/cm3, the other at a density of approximately 1.18-1.21 g/cm3.

Animals↗
PubMed1992

Solid-phase enzyme-linked immunosorbent assay for hepatitis E virus IgG and IgM antibodies utilizing recombinant antigens and synthetic peptides.

Four recombinant antigens representing two distinct antigenic domains from two different strains of hepatitis E virus (HEV), were used individually to develop four ELISAs designed to detect antibodies to HEV. Both IgG and IgM class antibodies to HEV were detected in 7 of 8 pedigreed serum/plasma from known outbreaks of HEV in Mexico, Burma, Somalia and Pakistan. In addition, specific HEV-antibodies were detected in cynomolgus macaques following inoculation with various HEV strains. Anti-HEV was also detected in 8 of 386 (2.1%) randomly selected American blood donors. Supplemental tests utilizing both synthetic peptides and specific blocking assays provided additional serologic data confirming the presence of anti-HEV. Similar prevalence studies on a limited number of available sera from other geographical regions (Alaska, Japan, Germany, New Zealand, Thailand and Mexico) confirmed the presence of anti-HEV in at least 1.1 to 7.6% of the specimens.

Animals↗
PubMed1991

IgM-antibody response to hepatitis C virus antigens in acute and chronic post-transfusion non-A, non-B hepatitis.

A specific IgM solid-phase enzyme-linked immunoassay for the diagnosis of a recent infection by hepatitis C virus (HCV) was developed. The assay utilizes a structural antigen encoded by sequences at the 5' end of HCV (core region) and non-structural (NS) antigens encoded by the NS-3 (33c) and NS-4 (c100-3) regions of the HCV genome. Serial serum samples from several clinically diagnosed post-transfusion non-A, non-B hepatitis patients were analyzed for anti-HCV IgM. This antibody was frequently but transiently detected. Anti-HCV core IgM was more frequently detected than anti-c100-3 or anti-33c IgM. In individuals who resolved their HCV infection or progressed to chronicity, anti-HCV IgM was produced transiently at or near the onset of clinically diagnosed acute hepatitis.

Acute Disease↗
PubMed1990

Prevalence of specific antibodies to herpes simplex virus type 2 as revealed by an enzyme-linked immunoassay and western blot analysis.

A solid-phase ELISA for the detection of antibodies to gG-2 was developed. The assay utilizes a recombinant DNA-derived gG-2 as a solid-phase "capture" reagent and goat anti-human IgG (gamma) conjugate to horseradish peroxidase as a probe (detector) reagent. A total of 229 serum samples collected from various populations were tested by ELISA and western blot analysis. On comparison with confirmed HSV-2 infection, the sensitivity and specificity of the ELISA were 92.9% and 98.7%, respectively. Western blot had a sensitivity of 83.9% and a specificity similar to the ELISA. The ELISA is fast and easy to perform and may be used to diagnose previous exposure to genital herpes and to monitor human response to future HSV-2 vaccines.

Animals↗
PubMed1989

Preparation and characterization of monoclonal antibodies to rotavirus.

By utilizing a strain of cultivable simian rotavirus (SA-11) as an immunizing antigen, we prepared 4 clones of mouse-mouse hybridoma, namely C127, C139, C172, and C214 which secreted monoclonal antibodies against the immunogen itself, SA-11 and also against other group A strains such as Wa and S2. Western blot analyses revealed that all of these antibodies are directed against VP6, a 42 kDa major inner capsid protein of group A rotavirus. Competitive experiments suggested that C127, C172 and C214 recognized three distinct epitopes on VP6, while C139 appeared to react with an epitope at or near the same epitope recognized by C172. We developed a two-step ELISA with excellent sensitivity and specificity for rotavirus detection by utilizing C127 and/or C214 as a capture antibody and rabbit anti-rotavirus conjugated with horseradish peroxidase as a probe. Also, when both monoclonal C127 capture antibody and polyclonal rabbit anti-rotavirus-HRP were incubated with rotavirus simultaneously in a one-step assay, equivalent sensitivity and specificity were observed. The data show that these generated anti-rotavirus antibodies can be utilized effectively as reagents for the detection of human rotaviruses in stool specimens.

Animals↗
PubMed1989

TestPack Chlamydia, a new rapid assay for the direct detection of Chlamydia trachomatis.

TestPack Chlamydia (Abbott Laboratories) is a rapid enzyme immunoassay for the direct antigen detection of Chlamydia trachomatis in endocervical specimens. The assay is self-contained, requires no specialized equipment, and yields results in less than 30 min. The clinical performance of TestPack Chlamydia versus chlamydial cell culture was evaluated with a total of 1,694 paired endocervical specimens. Discordant samples were further investigated by immunofluorescent staining and by Chlamydiazyme immunoassay, with confirmatory procedures. The sensitivity of TestPack Chlamydia with less-than-48-h-old specimens was 76.5%, while culture sensitivity was 86.7%. TestPack Chlamydia specificity was determined to be 99.5%. These results indicate that TestPack Chlamydia is an accurate test for chlamydial infection, with a positive predictive value of 96.2%. This assay is suitable for low-volume chlamydial testing in physician offices, clinics, and smaller laboratories.

Antigens, Bacterial↗
PubMed1988

Delta virus infection in Jerusalem.

The role of hepatitis delta virus (HDV) infection was analyzed retrospectively in a highly selected population of 76 patients who were hospitalized in Jerusalem for hepatitis B surface antigen positive for chronic active hepatitis and cirrhosis. Of 25 patients in whom serum and liver tissue were available, 5 patients (20%) showed evidence for HDV infection using a serum anti-HDV IgG radioimmunoassay; in one of them, HDV was also detected in nuclei of infected hepatocytes by immunofluorescence (IF). When only serum was tested, 12 of 45 patients (27%) were anti-HDV IgG positive. The use of IF alone had a very low yield of HDV detection. All HDV-positive patients with available serum had superinfection with the delta agent as confirmed by a negative anti-HBc IgM assay. The majority of HDV-positive patients were immigrants from Rumanian or Middle Eastern and Mediterranean origin. The mean age of delta-positive patients was 10 years lower at clinical presentation as compared with HDV-negative patients. HDV-positive patients had a higher mortality as compared with the HDV-negative group. In conclusion, HDV infection is prevalent among Israeli patients with chronic liver disease and persistent hepatitis B virus infection and leads to a significant morbidity and mortality.

Adolescent↗
PubMed1987

Delta agent infection in Riyadh, Saudi Arabia.

Blood samples from 186 HBsAg-positive Saudis and 42 HBsAg-positive Philippino blood donors were tested for anti-delta using the radioimmunoassay technique. The high prevalence of anti-delta in Saudis with liver disease (32%) contrasted sharply with that in Saudis with illness other than liver disease (13%) and in apparently healthy Saudis (5.4%). Together with the high prevalence of anti-delta in Philippino blood donors (9.5%), these results suggest that foci of endemic delta infection other than Italy probably exist.

Female↗
PubMed1987

A biotin/avidin solid-phase sandwich enzyme immunoassay for the antibody to hepatitis B surface antigen (anti-HBs).

A biotin/avidin solid-phase enzyme immunoassay for the detection and quantitation of the antibody to hepatitis B surface antigen (anti-HBs) is described. The assay utilizes hepatitis B surface antigen (HBsAg) as a solid-phase 'capture' reagent and a mixture of biotinylated HBsAg and avidin-conjugated horseradish peroxidase as a probe 'detector' reagent. The assay was compared to a commercial radioimmune assay for anti-HBs detection. The two assays were found to measure the same molecules and to correlate well regarding anti-HBs titers.

Avidin↗
PubMed1987

The utilization of biotin-antibiotin interaction for the detection of antibody to hepatitis B surface antigen (anti-HBs).

A biotin-antibiotin solid-phase enzyme-linked immunoassay for the detection and quantitation of the antibody to hepatitis B surface antigen (anti-HBs) is described. The assay utilizes hepatitis B surface antigen as a solid-phase 'capture' reagent and a mixture of biotinylated HBsAg and antibiotin-conjugated horseradish peroxidase as a detector reagent. The assay was compared to a commercial enzyme immunoassay (AUSAB EIA) which used the biotin-avidin system for anti-HBs detection. The two assays were found to measure the same molecules and to correlate well regarding anti-HBs titers.

Biotin↗
PubMed1986

Hepatitis A infection in New Zealand children.

Antibody to hepatitis A virus (anti HAV), a marker of past infection, was assayed in 2000 sera collected as part of a national survey in 1978-79. The sera were obtained from children and young people aged 0-21 years, resident in all health districts of New Zealand. Anti HAV was detected in 307 sera, giving an overall prevalence of 15.4%. Prevalence increased steadily throughout childhood but more slowly during adolescence. There was no sex differential, the age-standardised rate/100 being 15.5 (95% confidence interval 13.2, 17.8) for males and 16.6 (14.4, 18.9) for females. However, the age-standardised rate for Maoris was 39.5 (33.2, 45.8) compared to 16.1 (12.8, 19.4) for Europeans, giving a risk ratio of 2.1. In addition, a marked north-south gradient in prevalence was demonstrated: the rate for children in the northern half of the North Island, when standardised for age and ethnicity, was 19.8 (16.8, 22.7) compared to 5.2 (3.2, 7.1) for South Island children, giving a risk ratio of 3.8. The higher prevalence of hepatitis A infection in Maori and northern North Island children mirrors our previously reported findings regarding markers of hepatitis B infection in this serum collection.

Adolescent↗
PubMed1986

Re-examination and further characterization of a monoclonal antibody to hepatitis B e antigen (anti-HBe).

A purification procedure for serum hepatitis B e antigen (HBeAg) was developed to immunize mice for monoclonal anti-HBe production. Two monoclonal anti-HBe secreting hybridomas were identified. Immunoglobulin G (IgG2a) was isolated from each hybridoma and labeled with either 125I or horseradish peroxidase. Each label was used as a probe in solid phase immunoassays for HBeAg and anti-HBe detection. Both monoclonal antibodies recognized the beta epitope on HBeAg, but one consistently performed better as a probe. When this monoclonal probe was compared to commercially available polyclonal assays, it showed equivalent sensitivity and specificity.

Animals↗
PubMed1979

Viral hepatitis, type B. Studies on natural history and prevention re-examined.

Frozen serial serum specimens obtained from past studies on the natural history and prevention of Type B hepatitis in children were retested by radioimmunoassay for the following markers of hepatitis B infection: hepatitis B surface antigen (HBsAg) and antibody (anti-HBs), hepatitis B e antigen (HBeAg) and antibody (anti-HBe), and antibody to hepatitis B core antigen (anti-HBc). The interval between exposure and evidence of viremia (HBsAg) was as short as six days. HBsAg and HBeAg persisted for two to five months and occasionally for more than one year after recovery. After the disappearance of their respective antigens, anti-HBc and anti-HBs persisted for more than seven years and anti-HBe for one to two years. Treatment with hepatitis B immune globulin after exposure induced complete or partial protection or prolongation of the incubation period. Administration of heat-inactivated hepatitis B virus, MS-2 strain, to 29 children induced an inapparent infection in three, characterized by a transient appearance of HBsAg and HBeAg, and the persistence of anti-HBc, anti-HBe and anti-HBs for more than two years.

Aspartate Aminotransferases↗
PubMed1979

Cryptic association of e antigen with different morphologic forms of hepatitis B surface antigen.

When highly purified HBsAg particles, separated by rate zonal centrifugation into populations differing in predominant size, were tested for HBeAg, the e1 specificity was detected preferentially in association with particle fractions containing large filaments and Dane particles. These results were obtained both by agar gel diffusion and by radioimmunoassay for e antigen. The e antigen activity present in these fractions was potentiated by prior treatment of particles with Tween 80, suggesting cryptic localization of e1 specificity within or under the outer membrane. The HBeAg released by detergent treatment from a purified preparation composed predominantly of small-particle forms of HBsAg was separated by electrofocusing into a peak of nonparticulate e antigen in the pH range of 5.7--6.0. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed three major polypeptides in this preparation with approximate molecular weights of 25,000, 55,000, and 70,000. Furthermore, two additional peaks of e antigen activity were detected which migrated in association with HBsAg particles at isoelectric points of 4.4 and 5.5--5.6. The major portion of e antigen remained in association with particles after further purification by rate zonal centrifugation.

Animals↗