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At least 19 recordsLinked to original sources
PubMed1989

Purification and analysis of colonization factor antigen I, coli surface antigen 1, and coli surface antigen 3 fimbriae from enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli fimbriae are immunogenic and play a key role in intestinal colonization. Native colonization factor antigen I, coli surface antigen 1, and coli surface antigen 3 fimbriae were purified by a common method involving shearing, differential centrifugation, gel filtration, and density gradient ultracentrifugation. The compositions and N-terminal sequences were determined. Coli surface antigen 3 possesses two N-terminal isoforms, one of which matches the published DNA sequence, except for the previously proposed signal sequence cleavage point.

Amino Acid Sequence↗
PubMedDate not supplied

Study of cell surface antigens induced by herpes simplex virus. Note II. Some properties of the antigens.

Surface antigens induced by herpes simplex virus infection in HeLa cells remain unaltered after treatment of the cells with 2% formalin for 10 min or with 0.08% trypsin for 15 min at 37 degrees C. A longer trypsin treatment (for 1 hour) will cause gradual alterations in the virus-induced antigens. Hence, these antigens are proteins deeply implanted within the cellular membrane. Their mobility--optimal at 37 degrees C--allows aggregation of the antigens in the form of caps or patches by polyvalent ligands such as IgG.

Antigens, Surface↗
PubMed1980

[Prevalence of surface antigens (HBsAg), surface antibody (HBsAb) and anticore antibody (HBcAb) in hospital personnel and patients with and without hepatic pathology].

We studied hepatitis B virus surface antigen (HBsAg), surface antibody (HBsAb) and "core" antibody (HBcAb) prevalence in 166 among hospital personell and patients with and without liver disease. Results show there is a very high prevalence of hepatitis B virus markers in such populations and the presence of HBcAb in absence of the other markers varies from 6% in "high risk" subjects to 30.3% in cirrhotic patients. We conclude that HBcAb seems to be, at moment, the most sensitive serological marker either for epidemiological studies or diagnosis and, in some instances, for prognosis of hepatitis B virus liver diseases.

Adolescent↗
PubMed1999

Immunization of woodchucks with plasmids expressing woodchuck hepatitis virus (WHV) core antigen and surface antigen suppresses WHV infection.

DNA vaccination can induce humoral and cellular immune response to viral antigens and confer protection to virus infection. In woodchucks, we tested the protective efficacy of immune response to woodchuck hepatitis core antigen (WHcAg) and surface antigen (WHsAg) of woodchuck hepatitis virus (WHV) elicited by DNA-based vaccination. Plasmids pWHcIm and pWHsIm containing WHV c- or pre-s2/s genes expressed WHcAg and WHsAg in transient transfection assays. Pilot experiments in mice revealed that a single intramuscular injection of 100 microgram of plasmid pWHcIm DNA induced an anti-WHcAg titer over 1:300 that was enhanced by boost injections. However, two injections of 100 microgram of pWHcIm did not induce detectable anti-WHcAg in woodchucks. With an increase in the dose to 1 mg of pWHcIm per injection, transient anti-WHcAg response and WHcAg-specific proliferation of peripheral mononuclear blood cells (PMBCs) appeared in woodchucks after repeated immunizations. Four woodchucks vaccinated with pWHcIm were challenged with 10(4) or 10(5) of the WHV 50% infective dose. They remained negative for markers of WHV replication (WHV DNA and WHsAg) in peripheral blood and developed anti-WHs in week 5 after challenge. In contrast, woodchucks not immunized or immunized with the control vector pcDNA3 developed acute WHV infection. Two woodchucks immunized with 1 mg of pWHsIm developed WHsAg-specific proliferative response of PBMCs but no measurable anti-WHsAg response. A rapid anti-WHsAg response developed during week 2 after virus challenge. Neither woodchuck developed any signs of WHV infection. These data indicate that DNA-based vaccination with WHcAg and WHsAg can elicit immunity to WHV infection.

Amino Acid Sequence↗
PubMed1987

Investigation of cross-reactivity between commercially available antibodies directed against human, mouse, and rat lymphocyte surface antigens and surface markers on canine cells.

Using automated flow cytometry, 23 commercially available antibodies (all but one of them monoclonal) raised against surface antigens of specific populations of human, rat, and mouse lymphocytes were tested for cross-reactivity to peripheral blood lymphocytes from five clinically healthy adult dogs. Of all the antibodies tested, only the polyclonal anti-asialo GM1 directed against mouse NK cells, and the monoclonal antibodies anti-HLA-DR directed against the human class II antigen and anti-B1, a human pan B cell marker, consistently labeled subpopulations of canine lymphocytes.

Animals↗
PubMed1980

Status and significance of testing for hepatitis B surface antigen and surface antibody.

Following Blumberg's discovery of hepatitis B surface antigen (HBsAg), many attempts have been made to develop several in vitro diagnostic techniques for the detection of this antigen and its homologous antibody. The two-dimensional micro-Ouchterlony immunodiffusion has been the first technique used, rapidly replaced by procedures of increasing sensitivity characterized as second-generation and the currently available third-phase tests which include radioimmunoassay (RIA), reverse passive haemagglutination (RPHA), reverse passive latex agglutination (RPLA) and enzyme immunoassay (EIA). Among these, RIA appears to be the most sensitive and specific, whereas EIA, RPHA and RPLA have the advantage of long shelf-life of stable reagents, no need for sophisticated and expensive equipment and no hazard associated with the handling of radioactive isotopes. Moreover, the sensitivity of EIA should increase by objective reading with a colorimeter. The most sensitive method for the detection of surface antibody (anti-HBs) is again RIA, whereas passive haemagglutination (PHA) had the advantage of providing titres. Finally EIA, based on inhibition of a known amount of HBsAg, has at least the same sensitivity as PHA, but has the advantage that reagents are more stable and that it permits screening for both HBsAg and anti-HBs with the same reagents at the same time. The application of these highly sensitive techniques for the detection of HBsAg and anti-HBs has resulted in a consistent reduction in the incidence of post-transfusion hepatitis type B and in a better understanding of the aetiology, epidemiology and natural history of this infection.

Antibodies, Viral↗
PubMed1981

Immune response to stage-specific surface antigens of the parasitic nematode Trichinella spiralis.

Rats were infected with the nematode Trichinella spiralis and the primary serum antibody response to antigenic surface proteins of infective larvae, intestinal worms, and newborn larvae was studies. 1 wk after infection, the sera contained antibodies to surface antigens of both infective larvae and intestinal worms. These early sera, however, failed to react with newborn larvae surface antigens. In addition, adsorption of sera with living intestinal worms or infective larvae removed antibodies to surface antigens of the homologous stage only. Finally, the time-course of appearance of antibodies that mediate eosinophil adherence to the surface of each stage of the parasite. We concluded that in a primary infection in rats, the surface proteins of T. spiralis used in this study are antigenically stage specific. Furthermore, they could be targets for the stage-specific, antibody-dependent eosinophil-mediated destruction of this parasite, known to occur in vitro.

Animals↗
PubMed2002

Effect of transfusion of fresh-frozen plasma on recipients' antibodies to hepatitis B surface antigen and hepatitis B surface antigen status in countries where hepatitis B virus is endemic.

BACKGROUND AND OBJECTIVES: Antibodies to hepatitis B virus (HBV) that are passively acquired through transfusions may lead to confusion and inappropriate clinical decisions. We evaluated the effects of transfusing fresh-frozen plasma (FFP) on serological tests for HBV antibodies in patients without such antibodies. MATERIALS AND METHODS: Tests for HBV surface antigen (HBsAg), and for antibodies to HBV surface antigen (anti-HBs) and HBV core antigen (anti-HBc), were carried out using enzyme immunoassay on the FFP and sera of 50 patients transfused with FFP containing anti-HBs. RESULTS: After FFP transfusion, the incidences of 'false' positivity for anti-HBs and anti-HBc were 64% (32/50) and 100% (seven of seven), respectively, and of 'false' negativity for HBsAg was 18.8% (three of 16) in previously positive patients. The post-transfusion seropositivity for antibodies results from passive transmission, whereas the inability to detect HBsAg is the result of decreased detectable levels. CONCLUSIONS: Laboratory staff and clinicians alike should be cautious in interpreting the results of the HBV marker tests in patients who have recently been transfused, and in obtaining specimens for such studies.

Blood Transfusion↗
PubMed1990

7-amino-4-methylcoumarin-3-acetic acid-conjugated streptavidin permits simultaneous flow cytometry analysis of either three cell surface antigens or one cell surface antigen as a function of RNA and DNA content.

We have investigated the use of the new coumarin dye AMCA (7-amino-4-methylcoumarin-3-acetic acid), as a fluorochrome for multiple color fluorescence analysis by flow cytometry. AMCA is now commercially available as a streptavidin conjugate. Its excitation wavelength is optimal at 351/364 nm with a UV argon ion laser and it emits optimally in the blue at 450 nm. AMCA-conjugated streptavidin yields a fluorescence intensity comparable to that obtained with FITC-streptavidin. The emission spectrum of AMCA does not interfere with that of FITC and phycoerythrin and thus permits triple color analysis of cell surface antigens without requiring the need for important electronic compensation. A unique feature of AMCA conjugates was the possibility to determine the expression of a surface antigen as a function of cellular RNA and DNA levels stained with acridine orange. AMCA conjugates will thus facilitate multiple color analysis by flow cytometry.

Antigens, Differentiation↗
PubMed1998

Characterization of recombinant hepatitis B surface antigen using surface plasmon resonance.

Two commercial monoclonal antibodies were shown to interact with distinct epitopes within the major antigenic a determinant region of yeast recombinant hepatitis B surface antigen (rHBsAg) particles, contained in the hepatitis B vaccine, by using the surface plasmon resonance phenomenon on a BIAcore system. Apparent avidity for these antibodies were compared among different rHBsAg batches, showing the consistency of these epitopes. Furthermore, the effect of the alteration of these epitopes, achieved by chemical modifications, was readily reflected by changes in the apparent avidity for these antibodies. The procedures used in the present study provide a novel and efficient way to characterize rHBsAg particles present in different hepatitis B vaccine products.

Antibodies, Monoclonal↗
PubMed1983

Nonoverlapping antigenic sites of woodchuck hepatitis virus surface antigen and their cross-reactivity with ground squirrel hepatitis virus and hepatitis B virus surface antigens.

Five nonoverlapping antigenic sites (sites I through V) of woodchuck hepatitis virus surface antigen were identified with competitive binding assays involving monoclonal antibodies. Site I contributed to cross-reactions among surface antigens of hepatitis B-like viruses infecting woodchucks, ground squirrels, and humans. At least three distinct sites (sites I, II, and III) are responsible for cross-reactions between woodchuck and ground squirrel hepatitis virus surface antigens. Sites IV and V of woodchuck hepatitis virus surface antigen are not major cross-reactive sites, suggesting that these elicit virus-specific antibodies. There were no cross-reactions with duck hepatitis B virus surface antigen.

Animals↗
PubMed1999

Antibodies produced by mice immunized with recombinant vaccinia viruses expressing two different types of a major Theileria sergenti surface antigen (p32) react with the native surface antigen.

A 32 kDa major surface antigen, p32, of Theileria sergenti at the piroplasm stage is the main target of the host immune response. The immunogenic property of the p32 varies in some strains among the population of Theileria sergenti in Japan where the Chitose type and the Ikeda type are the most common varieties. We have constructed vaccinia virus recombinants vv/p32C and vv/p32I which harbor the Chitose and Ikeda types of p32 gene, respectively. It was found that vv/p32C and vv/p32I produced type-specific p32 which did not cross react with the monoclonal antibodies (mAbs) against the other type of p32. When mice were immunized with vv/p32C and vv/p32I, antibodies against p32 were detectable 2 weeks after the immunization, and these antibodies reacted with the native surface antigen in purified T. sergenti merozoite.

Animals↗
PubMed1999

Hepatitis B surface antigen disappearance and hepatitis B surface antigen subtype: a prospective, long-term, follow-up study of Japanese residents of Okinawa, Japan with chronic hepatitis B virus infection.

To determine the natural course of hepatitis B surface antigen (HBsAg) disappearance in chronic hepatitis B virus (HBV) infection and the factors related to its disappearance, 946 HBsAg carriers in Okinawa, Japan were prospectively followed for up to 19 years (mean = 9.2 years). The disappearance of HBsAg, as determined by radioimmunoassay (RIA), was observed in 62 (6.6%) and the overall annual disappearance rate was 0.79%/year. Its disappearance was more frequent in 60 (7.4%) of 815 serum samples negative for hepatitis B e antigen (HBeAg) by RIA at entry compared with only two (1.5%) of 131 serum samples that were HBeAg positive by RIA at entry (P < 0.05). Stepwise logistic regression analysis showed that age and HBsAg subtype were significantly associated with HBsAg disappearance (both P < 0.05), and that carriers with subtype adr (odds ratio = 2.87) had an increased probability of clearing HBsAg compared with carriers with subtype adw. Conversely, HBeAg disappearance was earlier in those with the adw subtype than in those with adr. Hepatitis B virus DNA was not detected by the polymerase chain reaction after HBsAg disappearance in any of the 62 from whom it had disappeared. The HBsAg titer, as measured by reverse passive hemagglutination, was related to the time to its disappearance; the higher the titer, the longer the time to disappearance. These findings suggest that HBeAg negativity, a more advanced age, and low titers of HBsAg are favorable factors for HBsAg disappearance in the natural course of chronic HBV infection. Moreover, HBsAg subtype adr was a predictive factor for HBsAg disappearance, whereas subtype adw was predictive of early HBeAg disappearance.

Adolescent↗
PubMed1990

Distinct effects of interferon-gamma and MHC class I surface antigen levels on resistance of the K562 tumor cell line to natural killer-mediated lysis.

Various investigators have examined the relationship between tumor cell susceptibility to natural killer (NK) cell lysis and the expression of HLA class I antigens on the tumor cell. There is controversy as to whether or not an inverse relationship exists, and if so, the basis of the relationship between these two phenomena remains undefined. To address these questions, the genomic clones for two HLA antigens were transfected into the erythroleukemia cell line K562, a cell line that is used as the standard to assess human NK and major histocompatibility complex (MHC) nonrestricted cytolysis. Susceptibility to NK lysis was not affected by the de novo expression of HLA antigens on the K562 after DNA mediated gene transfer. Interferon-gamma (IFN-gamma) treatment of K562 induced levels of MHC class I antigen surface expression comparable to those found on the transfected cells; however, the IFN-gamma-treated cells were resistant to NK lysis. When very high levels of surface HLA antigens were induced on the transfectants, a potential effect of class I MHC expression on K562 lysis could be discerned that was distinct from the resistance to NK lysis induced by IFN-gamma-treatment.

Antigens, Surface↗
PubMed1994

Cellular and humoral immune responses to well-defined blood stage antigens (major merozoite surface antigen) of Plasmodium falciparum in adults from an Indian zone where malaria is endemic.

Conserved and variant regions of two blood stage vaccine candidate antigens of Plasmodium falciparum, merozoite surface antigen (MSA-1) and ring-infected erythrocyte surface antigen (Pf155/RESA), have been shown to be immunogenic. However, the relative immunogenicity of these immunogens in different populations has not been studied. The conserved N-terminal region of MSA-1 was investigated for its immunogenicity by studying cellular (T cell) and humoral (B cell) immune responses in P. falciparum-primed individuals, living in malaria-hyperendemic areas (Orissa State, India), where malaria presents an alarming situation. MSA-1-derived synthetic peptides contained sequences that activated T cells to proliferate and release gamma interferon in vitro. There was considerable variation in the responses to different peptides. However, the highest responses (51% [18 of 35] by proliferation and 34% [12 of 35] by gamma interferon release) were obtained with a synthetic hybrid peptide containing sequences from conserved N- and C-terminal repeat regions of MSA-1 and Pf155/RESA, respectively. Antibody reactivities in an enzyme immunoassay of plasma samples from these donors to different peptides used for T-cell activation were heterogeneous. In general, there was poor correlation between DNA synthesis and either gamma interferon release or antibody responses in individual donors, underlining the importance of examining several parameters of T-cell activation to assess the total T-cell responsiveness of a study population to a given antigen. However, the results from our studies suggest that synthetic constructs containing sequences from the N- and C-terminal regions of MSA-1 and Pf155/RESA representing different erythrocytic stages of the P. falciparum parasite are more immunogenic in humans living in malaria-hyperendemic areas of India who have been primed by natural infection.

Adolescent↗