Enhancement of the immune response to hepatitis B surface antigen. In vivo administration of antiidiotype induces anti-HBs that expresses a similar idiotype.

BALB/c mice receiving antiidiotype antibodies before the injection of hepatitis B surface antigen (HBsAg) generated an enhanced anti-HBs response. Mice given antiidiotype antibodies in a soluble form induced predominantly IgM anti-HBs, whereas alum-precipitated antiidiotype produced primarily IgG anti-HBs. Injection of antiidiotype antibodies alone induced anti-HBs that inhibited a common interspecies anti-HBs idiotype-antiidiotype reaction and recognized the group-specific determinant of HBsAg. These data support the view that antiidiotype antibodies may modulate the immune response to an infectious viral agent.

Suppression of in vivo tumor formation induced by simian virus 40-transformed cells in mice receiving antiidiotypic antibodies.

This study characterizes four private idiotypes (Id) associated with monoclonal antibodies (mAb) to simian virus 40 (SV40) tumor antigen (T-Ag), and to a cellular protein, p53. Anti-Id recognized Id determinants associated with the antibody-combining site. BALB/c mice receiving a pool of anti-Id directed against mAb recognizing distinct amino and carboxyl terminal epitopes of T-Ag before receiving a tumorigenic dose of SV40-transformed cells showed suppression of tumor formation. Serum obtained from these mice before tumor challenge contained anti-anti-Id that failed to bind T-Ag. These data support the potential role of regulatory idiotopes in tumor immunity.

Antibody to hepatitis B virus induced by injecting antibodies to the idiotype.

Anti-idiotype reagents that recognize a common idiotype associated with antibody to hepatitis B surface antigen (anti-HBs) were used to induce anti-HBs in mice. The anti-idiotype-induced anti-HBs was found to recognize the group-specific a determinant of hepatitis B surface antigen and to express an interspecies idiotype. These findings suggest that anti-idiotypes may be useful as vaccines or vaccine primers.

Anti-idiotypic antibody vaccine for type B viral hepatitis in chimpanzees.

Anti-idiotypic antibodies (anti-Id) that contain an internal image component that mimics the surface antigen of hepatitis B virus (HBsAg) were used to immunize chimpanzees. Four injections of the rabbit anti-Id preparation elicited an antibody response to HBsAg (anti-HBs). The antibody specificity appeared to be against the anti-Id, since the anti-Id immunogen was shown to bind the chimpanzee anti-HBs. Two chimpanzees immunized with the anti-Id, along with two control animals that were either untreated or received a nonimmune rabbit immunoglobulin G preparation, were challenged with infectious hepatitis B virus. Both control chimpanzees developed clinical and serological characteristics consistent with an active hepatitis B virus infection, whereas the two anti-Id treated chimpanzees were protected from infection. Since chimpanzees provide a relevant model of a human response to hepatitis B virus immunization and infection, these results indicate that anti-Id preparations such as that described here might be candidates for vaccines against human diseases.

Antiserum to a synthetic peptide recognizes the HTLV-III envelope glycoprotein.

In a study performed to determine which regions of the human T-cell lymphotrophic virus type III (HTLV-III) may represent vaccine candidates to prevent the acquired immune deficiency syndrome (AIDS), a synthetic peptide corresponding to amino acid sequence 735 to 752 of the precursor envelope glycoprotein of HTLV-III was used to immunize rabbits. The resulting rabbit antiserum to the synthetic peptide specifically recognized the precursor envelope glycoprotein (gp160) of HTLV-III. Human sera positive for antibody to HTLV-III reacted with this peptide. These findings indicate that synthetic peptides can be used to induce an immune response directed against a native envelope glycoprotein epitope of HTLV-III. The data are discussed in terms of using synthetic peptides to identify antigenic determinants involved in the induction of protective immunity and possibly as vaccine candidates against the etiologic agent of AIDS.

Immune response to hepatitis B surface antigen: enhancement by prior injection of antibodies to the idiotype.

Anti-idiotype reagents that recognize a common idiotype associated with the combining site of antibodies to hepatitis B surface antigen (anti-HBs) were used to manipulate the immune response to hepatitis B surface antigen in BALB/c mice. The injection of antibodies to the idiotype before antigenic stimulation resulted in an increase in the number of cells secreting immunoglobulin M antibodies to hepatitis B surface antigen. Anti-HBs-secreting cells were also induced by administration of antibodies to the idiotype without subsequent antigen exposure. These findings indicate that the immune response to hepatitis B surface antigen in mice is regulated through an idiotype-anti-idiotype network.

Conserved sequence and structural elements in the HIV-1 principal neutralizing determinant.

The principal neutralizing determinant (PND) of human immunodeficiency virus HIV-1 is part of a disulfide bridged loop in the third variable region of the external envelope protein, gp120. Analysis of the amino acid sequences of this domain from 245 different HIV-1 isolates revealed that the PND is less variable than thought originally. Conservation to better than 80 percent of the amino acids in 9 out of 14 positions in the central portion of the PND and the occurrence of particular oligopeptide sequences in a majority of the isolates suggest that there are constraints on PND variability. One constraining influence may be the structural motif (beta strand--type II beta turn--beta strand--alpha helix) predicted for the consensus PND sequence by a neural network approach. Isolates with a PND similar to the commonly investigated human T cell lymphoma virus IIIB (HTLV-IIIB) and LAV-1 (BRU) strains were rare, and only 14 percent of sera from 86 randomly selected HIV-1 seropositive donors contained antibodies that recognized the PND of these virus isolates. In contrast, over 65 percent of these sera reacted with peptides containing more common PND sequences. These results suggest that HIV vaccine immunogens chosen because of their similarity to the consensus PND sequence and structure are likely to induce antibodies that neutralize a majority of HIV-1 isolates.

Antibody to herpes simplex virus type 2-induced nonstructural proteins in women with cervical cancer and in control groups.

Sera obtained from 15 patients with cervical cancer, 10 patients with breast cancer, and 15 control women, individually matched with the cervical cancer patients, were examined for antibodies to early proteins synthesized in herpes simplex virus type 2 (HSV-2)-infected cells. The method used was an indirect radioimmune precipitation test followed by polyacrylamide gel electrophoretic analysis of immune precipitates. The relative reactivity to a major early nonstructural protein (VP134) was used to compare these selected sera. The results obtained suggest that cervical cancer patients possess sera with a higher reactivity to VP134 than breast cancer patients or matched healthy women,and that serum reactivity is independent of the level of neutralizing antibodies to HSV-2.

Studies on herpes simplex virus and cancer.

Virus-induced polypeptides of cells infected by herpes simplex virus (HSV) types 1 and 2 were investigated by analysis on polyacrylamide gels and by determination of their antigenicity. Some polypeptides, VP154 and VP134, had immunological reactivity common to both virus types, while others (VP175 and VP123) were type specific. Only the glycosylated polypeptides were able to induce neutralizing antibody. The expression of viral genetic information was studied in newborn mice infected with wild-type and ts mutant viruses; some mutants had become attenuated and had lost pathogenicity for newborn mice while others had not. From induction experiments in HSV=transformed hamster cells, it appears that detection of enhanced replication of ts mutants in human cancer cells would be an indication of resident HSV genetic information. Sera obtained from cancer patients were examined for antibodies to early proteins synthesized in HSV-infected cells. The method used was an indirect radioimmune precipitation test followed by polyacrylamide gel electrophoretic analysis of immune precipitates. Cervical cancer patients had sera with a higher reactivity to early nonstructural polypeptides than to breast cancer patients or to matched healthy women. In contrast to the results with early polypeptides, little difference was detectable between the matched sera in their reactivity with a major capsid polypeptide, which is synthesized late in the infectious cycle.

Utilization of the biotin/avidin system to amplify the sensitivity of the enzyme-linked immunosorbent assay (ELISA).

The biotin/avidin system was incorporated into the enzyme-linked immunosorbent assay (ELISA) technique to increase the sensitivity of the standard ELISA for the detection of mouse antibody to hepatitis B surface antigen ((anti-HBs and HBsAg, respectively). Two biotin/avidin ELISA designs were studied. In both assays, 96-well polystyrene plates were coated with HBsAg, post-coated with 0.5% gelatin and incubated with dilutions of mouse anti-HBs. In the biotin/avidin (BA) ELISA, reagents were added to antibody reacted wells in the following sequence: biotinylated goat anti-mouse IgG (b-GAMG), avidin-alkaline phosphatase (Av-AP) and substrate. The order of reactants after mouse antibody in the biotin/avidin/biotin (BAB) ELISA was b-GAMG, avidin, biotinylated alkaline phosphatase (b-AP) and substrate. The sensitivities of BA ELISA, BAB ELISA and a standard ELISA using a glutaraldehyde conjugated goat anti-mouse enzyme were compared to AUSAB (a commercial radioimmunoassay) using a panel of 23 mouse anti-HBs sera. All 3 ELISAs were more sensitive than AUSAB; the standard ELISA, BAB ELISA and BA ELISA were respectively 50, 1173 and 4134 times more sensitive than AUSAB for detection of mouse anti-HBs activity.

Immunological and biophysical properties of hepatitis B antigen labeled by the chloramine-T and by the lactoperoxidase methods.

Optimal conditions were sought for the radiolabeling of microgram quantities of hepatitis B surface antigen (HBs Ag) employing the chloramine-T or lactoperoxidase iodination procedures. Preparations of HBsAg labeled by these procedures are referred to as chloramine-T preparations and lactoperoxidase preparations, respectively. Labeled HBsAg having specific activities between 10-20 muCi/mug were found to display the greatest degree of sensitivity for unlabeled HBsAg and for anti-HBs using a double-antibody radioimmunoassay (RIA-DA). Increasing the specific activity above this level redulted in a decreased affinity of labeled 1251-HBs Ag for anti-HBs, indicating that soluble antigenic alterations had developed. At equivalent specific activities, chloramine-T preparations competed less effectively for unlabeled HBs Ag than lactoperoxidase preparations, and anti-HBs endpoint titers were slightly reduced, especially among preparations of high specific activity (greater than or equal to 65 muCi/mug). Chloramine-T preparations of HBs Ag (sp. act. 15--30 muCi/mug) showed essentially no antigenic deterioration over a 2-month period at minus 196 degrees C or minus 70 degrees C. Utilization of optimally labeled 1251-HBs Ag has increased the sensitivity of the RIA-DA for unlabeled HBs Ag 30-fold to a level below 1 ng/ml and enhanced antiamine-T method revealed that only the most acidic population was labeled (pH 3.75+/-0.5). In contrast, six antigenic components with distinct pI values ranging from 3.7 to 5.2 were detected by RIA-DA in both unlabeled HBs ag and in the chloramine-T preparation. This indicated that the chloramine-T method did not radically change the relative number or charge of each of the pI populations present in purified preparations of HBs Ag. Analysis of HBs Ag iodinated by the lactoperoxidase procedure revealed the presence of three of four populations of particles with pI values ranging from 3.9 to 4.5, suggesting that this procedure labels HBs Ag more uniformly.

Enzyme potentiated radioimmunoassay (EPRIA): a sensitive third-generation test for the detection of hepatitis B surface antigen.

A sensitive, specific immunoassay for detection of hepatitis B surface antigen (HBsAg) is described. The assay combined enzyme-linked immunosorbent assay and solid-phase radioimmunoassay and is termed enzyme potentiated radioimmunoassay (EPRIA). HBsAg was quantitated by enzymatic conversion of L[14C]glutamic acid to 14CO2 and gamma-aminobutyric acid by glutamate decarboxylase (GDC) conjugated wih goat anti-HGs IgG. Conjugation of IgG and GDC was by a thiol-disulfide bond exchange reaction after reacting N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) with each reagent. A positive/negative ratio of 2.2 was established as significant by examination of 40 normal sera negative for HBsAg. This value was the mean cpm plus 3 standard deviations. By an identical statistical analysis of sensitivity, EPRIA was found to be approximately 100-fold more sensitive than Ausria II (Abbott Laboratories, North Chicago, IL).

Expression and characterization of hepatitis B virus precore-core antigen in E. coli.

The hepatitis B virus core antigen, including the precore sequence (HBcAg-p25), was expressed at very high levels in bacteria. Three expression vectors were constructed in which the synthesis of HBcAg-p25 was controlled by the tac promoter, and the number of nucleotides between the bacterial ribosome binding site and the precore initiation codon was varied in order to maximize HBcAg-p25 synthesis. The relative amount of HBcAg-p25 polypeptide expressed by the different vectors was estimated by SDS-polyacrylamide gel electrophoresis and immunoblot. HBcAg-p25 was associated with an insoluble fraction of bacterial extracts and required ionic detergents for solubilization. Comparison by ELISA of the immunoreactivity of HBcAg with and without the precore sequence suggested that human anti-HBcAg IgG preferentially recognizes HBcAg lacking the precore sequence.

Detection of viral hepatitis type A.

Several technics are currently being used to detect hepatitis type A antigen or its antibody. These include immunoelectronmicroscopy, immune adherence, and complement fixation. This paper describes another promising technic, a microtiter solid-phase immunoradiometric assay, in which hepatitis A antigen and antibody are detected. Such a method can be utilized for biochemical and biophysical analysis of purified particles, for the seroepidemiology of type A hepatitis, and as a means for monitoring hepatitis A antigen in cell cultures.

Production and characterization of anti-idiotype reagents for the analysis of viral antigen systems.

Anti-idiotype reagents have been used recently in the characterization of a number of viral systems. These reagents provide a relatively new approach in viral immunology for the analysis of specific antibody molecules to viruses and their associated antigenic determinants. In this paper we report on the methodology for the generation and characterization of xenogeneic anti-idiotype antibodies in rabbits.

Development of sensitive immunoassays for detection of antibodies against hepatitis B surface antigen.

Three micro solid phase immunoassays (a micro-SPRIA and two ELISA techniques) were developed and tested for the detection of anti-HBs antibodies. Two different crosslinkers (glutaraldehyde and N-succinimidyl 3-(2-pyridyldithio) propionate) were used to couple a goat anti-mouse IgG reagent to alkaline phosphatase for use as enzyme-labeled probes in the two ELISA tests. With the latter crosslinker, a defined conjugate with a 1:1 antibody-enzyme molar ratio was obtained. The sensitivities of micro-SPRIA and the two types of ELISA were compared to that of the commercial solid phase radioimmunoassay AUSAB test. All three microtests were significantly more sensitive than the AUSAB test. The ELISA using the glutaraldehyde cross-linked conjugate was 3-5 times less sensitive than micro-SPRIA, while the ELISA using the disulfide-linked conjugate was 2.6-4.0 times more sensitive than micro-SPRIA.

A micro solid-phase radioimmunoassay for detection of herpesvirus type-specific antibody: parameters involved in standardization.

A micro solid-phase radioimmunoassay (micro-SPRIA) was developed to demonstrate type-specific antibodies to herpes simplex virus types 1 and 2 (HSV1 and HSV2). Glycoproteins from the 123,000 dalton region of HSV1 (VP123) and the 119,000 dalton region of HSV2 (VP119) were isolated on preparative polyacrylamide gels for use as antigens in the micro-SPRIA. Human sera selected from clinical samples by virological history and appropriate microneutralization data were used to standardize the micro-SPRIA. Optimization of the assay required the use of siliconized microtiter wells for adsorption of antigen. Maximized results were highly dependent on the concentrations of antigen, primary antibody, and secondary antibody as well as the diluents used for these principal test reagents. Incorporation of HSV glycoproteins of each respective type with the optimal condition established in this study facilitates the direct detection of type-specific antibody in human sera.

A micro solid-phase radioimmunoassay for detection of herpesvirus type-specific antibody: specificity and sensitivity.

The specificity and sensitivity of a micro solid-phase radioimmunoassay (micro-SPRIA) that detects type-specific IgG antibody to herpes simplex virus types 1 and 2 (HSV1 and HSV2) were evaluated. Glycoproteins VP123 (molecular weight, 123,000) of HSV1 and VP119 (molecular weight, 119,000) of HSV2 were found to display the greatest degree of antigenic type-specificity of several HSV antigens tested with the micro-SPRIA technique. When testing a group of sera, negative for anti-HSV antibodies by microneutralization, in the micro-SPRIA, a range of negative reactivities was noted, suggesting that cut-points should be determined for each antigen preparation. The micro-SPRIA detected appropriate antibody activity in patients with recurrent infection and a marked agreement was noted in comparison to detection of anti-HSV antibodies measured with the microneutralization test. The type-specificity of the micro-SPRIA was substantiated by the independence of test results using VP119 and VP123 antigens for a random group of positive sera. The assay is rapid, specific, and sensitive and allows the testing of multiple serum samples with a standardized set of reagents.