[en] A process for detecting the presence of an antigen in a specimen is described, which process comprises: contacting said specimen with a substrate coated with antibodies of said antigen, incubating the contacted substrate and washing the substrate; contacting the washed material of step with a hapten conjugated antibody against said antigen, incubating the so-contacted material and washing the so-incubated material; contacting the washed material of step with a radioactive material labeled or enzyme containing anti-hapten antibody, incubating the so-contacted material and washing the same; and effecting radioimmunoassay if said antibody is radioactive or enzyme labeled immunoassay if said antibody contains an enzyme moiety. Quantitative determination of the antigen in the specimen is effected by comparing the counts of the radioimmunoassay or the concentration of enzyme against a standard as by photocolormetric methods

[en] Solid phase radioimmunoassays (IRA) were developed in which ¹²⁵I-labeled antibodies to individual antigens were replaced by dinitrophenylated antibodies. The antigen-bound antibodies were quantitated by measuring the subsequent attachment of ¹²⁵I-labeled anti-DNP. The described RIA has the following advantages: (1) A single radiolabeled antibody is used in all tests; (2) introduction of DNP groups into the primary antibodies leads to amplified radioactive tracer binding and (3) the necessity to purify each antibody immunochemically is eliminated. (author)

[en] The unavailability of serological tests for detection of several not yet characterized infectious agents transmitted by blood transfusion or by blood products prompted the development of alternative tests based on utilization of labeled nucleic acid probes specific for genomes of each of these agents. The prerequisite for the preparation of such probes is the demonstration in human plasma of nucleic acid sequences distinct from those present in host DNA or in genes of already characterized viruses occurring in plasma of infected individuals. To accomplish this, ultrasensitive tests for nucleic acids not dependent on their base sequence are needed. The authors describe a radioimmunoassay (RIA) for picogram quantities of DNA. Plasma (serum) specimens are treated with proteinase K in the presence of sodium dodecyl sulfate and extracted with phenol. Nucleic acids are precipitated with ethanol in the presence of dextran (mol.wt. approx. 5X10⁵) as carrier. Subsequently, DNA from the redissolved samples is adsorbed onto polylysine-coated wells of microtiter plates and detected by a double-antibody RIA using anti-DNA autoantibodies from NZB/NZW mice and ¹²⁵I-labelled antibodies to mouse immunoglobulins. DNA which did not hybridize with human DNA was detected by this method in sera containing hepatitis B virus used as a model system. (Auth.)

[en] A radioimmunoassay for hepatitis B e-antigen (HBeAg) is described. Polystyrene beads coated with IgG prepared from a human serum containing antibodies to HBeAg(anti-HBe) and anti-HBe IgG labelled with ¹²⁵I-p-hydroxy-phenylpropionic acid N-hydroxysuccinimide ester were used in the test. The radioimmunoassay was approximately 1000-fold more sensitive than immunodiffusion. At least a transient presence of HBeAg in serum appears to be a common feature of infections by hepatitis B virus. The radioimmunoassay was instrumental in establishing conditions for identification of apparently free monomeric HBeAg. The HBeAg has an approximate mol wt. of 35000 and was recovered after isoelectric focusing in fractions with a pH between 4.25 and 4.8. Polyacrylamide gel electrophoresis revealed the presence in HBeAg of a polypeptide with an apparent mol. wt. of 17000. (author)

[en] A solid-phase radioimmunoassay for antibodies to hepatitis B core antigen (anti-HBsub(c)) is described. Polystyrene beads coated with anti-HBsub(c), hepatitis B core antigen prepared from pooled sera of humans infected with hepatitis B virus (HBV) and ¹²⁵I-labelled anti-HBsub(c) were used for the test. Distinct patterns of development and changes of anti-HBsub(c) and their immunological properties are all related to variations of other markers specific for HBV infections. Knowledge concerning the detailed features of the immune response to hepatitis B core antigen may provide deeper insight into the pathogenesis of HBV infections. (author)

[en] Antigens corresponding to infectious agents may be present in biological specimens only in a cryptic form bound to antibodies and, thus, may elude detection. We describe a solid-phase technique for separation of antigens from antibodies. Immune complexes are precipitated from serum by polyethylene glycol, dissociated with NaSCN, and adsorbed onto nitrocellulose or polystyrene supports. Antigens remain topographically separated from antibodies after removal of NaSCN and can be detected with radiolabeled antibodies. Genomes from viruses immobilized on nitrocellulose can be identified by nucleic acid hybridization. Nanogram quantities of sequestered hepatitis B surface and core antigens and picogram amounts of hepatitis B virus DNA were detected. Antibody-bound adenovirus, herpesvirus, and measles virus antigens were discerned by the procedure

[en] Human T-cell lymphotropic viruses designated HTLV III or LAV are considered to represent the causative agents of the acquired immunodeficiency syndrome (AIDS). Therefore a simple direct RIA or ELISA method for antibodies to distinct epitopes of HTLV III/LAV structural components would be of great value. The authors describe RIA and ELISA assays which obviate the need for purified virus or virus proteins, do not utilize infected cells and thus do not diminish the source for continuous production of viral antigens and are specific for a major core protein of HTLV III/LAV

[en] Molecular exclusion chromatography of crude LAV antigen preparations allows separation of most of P24 from larger proteins of LAV (PL). PL and ¹²⁵I- or beta-lactamase-labeled anti-LAV were used as reagents for radioimmunoassay (RIA) - or enzyme-linked immunoassay (ELISA) - inhibition tests to detect antibodies directed predominantly against PL (anti-PL). Among 257 individuals belonging to groups at high risk of developing AIDS, 117 (45.5%) were positive for anti-PL and 108 (42%) for anti-P24, respectively. The 2 individuals among 600 random blood donors found to be anti-P24-positive in the preceding study also had anti-PL in their serum. Sera from 500 additional blood donors were screened for anti-PL and 1 of these was positive. The implication of these findings for screening of blood donors is discussed. (Auth.)