A solid-phase radioimmunoassay involving specific antibody was developed for determination of the pre-S gene-encoded epitopes of hepatitis B virus and anti-pre-S antibody in sera of hepatitis B patients. The reaction for pre-S determinants associated with HBsAg was quantitatively inhibited by soluble, polymerized human serum albumin, and the lower limit of the assay was about 1.6 ng of HBsAg per ml. Continuous expression of pre-S-coded antigenic sites on HBsAg particles in chronic hepatitis B patients seropositive for HBeAg or anti-HBe shows that these determinants may be considered as a marker of chronicity during hepatitis B virus infection. The anti-pre-S antibody was determined by inhibition of the reaction for pre-S determinants. This antibody, different from anti-HBs, was detected during HBsAg antigenemia in patients recovering from acute type B hepatitis, before anti-HBs response. Kinetics of synthesis of anti-pre-S antibody in the course of acute type B hepatitis, followed by elimination of HBsAg and recovery, suggest the possible role of this antibody in the immunological clearance of infective hepatitis B virus particles.

Chronic Disease↗

PubMedDate not supplied

Significance of anti-IgG antibodies obtained by immunization of rabbits with some streptococcal strains.

Anti-human IgG antibodies have been found in a number of rabbit sera immunized with freshly isolated streptococci. The significance of these anti-IgG antibodies was investigated. An IgM rheumatoid factor was excluded because the antibodies to human IgG present in rabbit sera belonged to the IgG class and reacted with the different isotypes of the human 7 S IgG. No cross-reaction between streptococci and human IgG was found. The anti-IgG production could be attributed to the in vivo non-immunological binding of host IgG to the infecting streptococci, via their Fc(gamma) receptors. A strong adjuvant effect of streptococci for IgG was found, and it explained the noticeable induction of anti-IgG antibodies by trace amounts of immunogen bound to streptococci. The possible induction of anti-human IgG antibodies by streptococcal cells could be an alternative explanation of the numerous cross-reactions described between streptococci and different human tissues.

Animals↗

PubMedDate not supplied

Hepatitis-E-virus-associated antigen: improved detection in stools by protein Fv removal.

ELISA detection of a hepatitis-E-virus-associated antigen (HEV-AAg) in stools was reappraised for its possible interference with a new Fab-binding factor, termed protein Fv, released during infectious hepatitis. Transaminase elevation, HEV-AAg discharge and Fv leakage appeared simultaneously in a Cercopithecus monkey inoculated with infected stools. Labelled normal, or immune human IgG, were compared with pre- and post-inoculation simian IgG, for HEV-AAg and Fv detection. Coated normal and patient human IgM were also compared to pre- and post-inoculation simian IgM in HEV-AAg and Fv capture assays. Simian IgM and beta-galactosidase-labelled simian IgG minimized Fv interference and appeared to be the best adapted system for HEV-AAg detection. Nevertheless, Fv was still the cause of false-positive interpretations in some cases; therefore adsorption with monoclonal IgM was required to ensure HEV specificity. The improved test was performed on stools from 30 Senegalese patients hospitalized for various sporadic attacks of viral hepatitis. HEV-AAg was detected in 6 out of 30 cases and no positivity was observed in patients suffering from hepatitis due to HAV, HBV, cytomegalovirus or Epstein-Barr virus. The specificity of the assay was confirmed by inhibition experiments with the sera from HEV-infected patients. Hence, this inhibition assay can also be used to detect serum antibodies to HEV-AAg.

Animals↗

PubMedDate not supplied

Polymerase chain reaction to monitor repair of the HBV genome, the first step in viral replication.

A method based on the polymerase chain reaction (PCR) for evidencing repair of the hepatitis B virus (HBV) genome is described. Hepadnaviruses have a partially double-stranded relaxed circular genome (RC-DNA) which is converted into a covalently closed circular DNA (CCC-DNA) after entry of the virus into a target cell. Our aim was to set up a technique enabling us to determine whether possible in vitro replication of the virus in non-hepatic cells is initiated by formation of CCC-DNA. The relevant part of the strategy used for this PCR consisted of priming the HBV-DNA template with the same forward primer and with a reverse primer located either downstream or upstream from the minus strand gap. The CCC-DNA form was found, as expected, in cells in which the virus was known to be actively replicating; although most sera contained only the RC-DNA form, it was also possible to evidence the CCC form. Such PCR amplification led to detection of 50-500 copies of the viral DNA. The method described should be useful in studying the biological fate of HBV in non-hepatic cells (considered as non-permissive for virus replication), and in exploring the clinical significance of the presence of CCC-DNA in sera.

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Detection of antibodies directed against the pre-S gene product of hepatitis B virus: relationship between anti-pre-S response and recovery.

A haemagglutination test and a radioimmunoassay were developed for determination of the pre-S-gene-encoded antigenic specificity of hepatitis B virus. The reaction for pre-S-coded determinants was specifically inhibited by the antibody produced in patients recovering from acute type B hepatitis. Kinetics of synthesis of anti-pre-S antibody in the course of acute type hepatitis followed by elimination of HBsAg and recovery suggest the important role of this antibody in immunological neutralization and clearance of infective HBV particles. The possible protective role of anti-pre-S antibody and the use of pre-S-determinant-positive HBsAg particles in HBV vaccines should be considered.

Genes↗

PubMedDate not supplied

A new simple blot transfer method following cellogel electrophoresis which preserves antibody activity: application to the analysis of monoclonal and oligoclonal fluids.

Electrophoresis on gelatinized cellulose acetate (cellogel), followed by a simple blot transfer onto a nitrocellulose membrane, allows analysis of the electrophoretic pattern of specific antibody-active molecules by their binding of radiolabelled antigen. Using this non-denaturing method, it is easy to establish the monoclonal or oligoclonal nature of an antibody activity present in a serum or to control the cloning of a hybridoma cell line. Comparison between protein staining and autoradiography can afford a rough estimation of the relative affinities of different monoclonal antibodies towards the same antigen (in this case, the hepatitis B surface antigen). In addition, inhibition studies using other monoclonal antibodies directed against the same antigen may help to delineate the epitope specificity of antibodies.

Animals↗

PubMedDate not supplied

Rapid and constant detection of HIV antibody response in saliva of HIV-infected patients; selective distribution of anti-HIV activity in the IgG isotype.

Anti-HIV antibodies can be specifically detected with a sensitivity and a specificity of 100% in the saliva of all HIV-infected patients. A saliva collection device facilitates the sampling procedure, and if a rapid test is used, the diagnosis of infection can be established in as little as 10 min. The analysis of a group of CDC stage IV AIDS patients showed a decrease in lactoferrin (produced by the oral mucosa) in comparison with HIV-negative controls, associated with an increase in albumin (filtering from plasma), indicating an alteration of the mucosal barrier. The salivary anti-HIV-gp160 activity was largely carried by the IgG isotype whereas the salivary antibacterial activity (anti-Streptococcus sobrinus; anti-LPS from Escherichia coli) remained located in the IgA isotype as usually observed with all infectious agents. Salivary IgG carried a specific anti-gp160 activity 25-fold higher than that of serum IgG. Thus, significant local synthesis of specific IgG by oral mucosa was revealed as a characteristic of HIV infection.

Acquired Immunodeficiency Syndrome↗