Sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG in serum using a synthetic peptide, Cys-env gp46(188-224), as antigen.

A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using a synthetic peptide, Cys-env gp46(188-224) of HTLV-I, is described. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-Cys-env gp46 (188-224) conjugate and Cys-env gp46 (188-224)-beta-D-galactosidase conjugate. The complex formed consisting of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG. After washing to eliminate nonspecific IgG in the test serum and excess of the beta-D-galactosidase conjugate, the complex was eluted from the polystyrene balls with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. beta-D-Galactosidase activity bound to the (anti-human IgG gamma-chain) IgG-coated polystyrene balls was assayed by fluorometry. This assay was more sensitive and useful than the immune complex transfer enzyme immunoassay using Cys-Arg-env gp46(188-209) and other methods using HTLV-I as antigen.     

Sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (antihuman T-cell leukemia virus type I) immunoglobulin G in serum using a synthetic peptide, Ala-Cys-Env gp46(237-262), as antigen.

A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (antihuman T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using a synthetic peptide, Ala-Cys-env gp46(237-262), of HTLV-I is described. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-Ala-Cys-env gp46(237-262) conjugate and Ala-Cys-env gp46(237-262)-beta-D-galactosidase conjugate. The complex formed consisting of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG. After washing to eliminate nonspecific IgG in the test serum and excess of the beta-D-galactosidase conjugate, the complex was eluted from the polystyrene balls with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. beta-D-galactosidase activity bound to the (anti-human IgG gamma-chain) IgG-coated polystyrene balls was assayed by fluorometry. This assay was more sensitive than other methods using HTLV-I as antigen, and most negative and positive sera were discriminated. However, some results appeared to be false positive or false negative, and the peptide, Ala-Cys-env gp46(237-262), was suggested to be useful, in combination with other peptides, for improving the reliability of serodiagnosis by separately demonstrating antibodies against as many different epitopes of HTLV-I as possible.     

Immune complex transfer enzyme immunoassay for (anti-human T-cell leukemia virus type I) IgG in serum using a synthetic peptide, Env gp46(188-209), as antigen

An immune complex transfer enzyme immunoassay for (anti-human T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using a chemically and safely synthesized peptide, env gp46(188-209), is described. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with dinitrophenyl bovine serum albumin-env gp46(188-209) conjugate and env gp46(188-209)-beta-D-galactosidase conjugate. The complex formed of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-dinitrophenyl group) IgG. After washing to eliminate nonspecific IgG in the test serum and excess of the beta-D-galactosidase conjugate, the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. beta-D-Galactosidase activity bound to the (anti-human IgG gamma-chain) IgG-coated polystyrene balls was assayed by fluorometry. This assay was sensitive and detected anti-HTLV-I IgG in serum samples which were negative by the conventional enzyme immunoassay and Western blotting. And the specificity of this assay was confirmed by preincubation of test serum with excess of env gp46(188-209). However, some disadvantages were also noted.     

Sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG in serum using recombinant gag p24(14-214) as antigen.

A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using recombinant gag p24(14-214) of HTLV-I is described. The recombinant gag p24(14-214) is soluble in the absence of detergents and allows the use of enzymes other than horseradish peroxidase as a label in the assays. The usefulness of recombinant gag p24(14-214) was examined with 305 sera characterized by other methods including gelatin particle agglutination, enzyme-linked immunosorbent assay (ELISA) using HTLV-I, and Western blotting. This assay was more sensitive than other methods using HTLV-I as antigen. The specificity could be tested by preincubation of test serum with excess of the recombinant protein. Most of negative and positive sera were discriminated. However, some results appeared to be false-positive or false-negative, and recombinant gag p24(14-214) was suggested to be useful, when used with other recombinant proteins and/or peptides, for improving the reliability of serodiagnosis by separately demonstrating antibodies against as many different epitopes of HTLV-I as possible. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-recombinant gag p24(14-214) conjugate and recombinant gag p24(14-214)-beta-D-galactosidase conjugate. The complex formed consisting of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) for antihuman T cell leukemia virus type 1 IgG in human serum using recombinant gag-env hybrid protein as antigen

A novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) for antihuman T cell leukemia virus type 1 IgG (anti-HTLV-1 IgG) in human serum using recombinant gag(14-139)-env-(197-295) hybrid protein is described. Anti-HTLV-1 IgG in test serum was reacted with dinitrophenyl biotinyl bovine serum albumin-recombinant gag-env hybrid protein conjugate. The complex formed was trapped onto polystyrene balls coated with affinity-purified antidinitrophenyl group IgG. After washing to eliminate nonspecific IgG in the test serum, the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to polystyrene balls coated with streptavidin. After washing, anti-HTLV-1 IgG in the complex trapped onto the streptavidin-coated polystyrene balls was reacted with antihuman IgG gamma-chain Fab'-peroxidase conjugate. Peroxidase activity bound to the streptavidin-coated polystyrene balls was assayed by fluorometry. By transfer of the complex, the nonspecific binding of nonspecific human IgG was considerably reduced, and the detection limit of anti-HTLV-1 IgG in serum was lowered 30-300-fold compared with that by Western blotting, gelatin particle agglutination, and the conventional enzyme immunoassay, in which a recombinant gag-env hybrid protein-coated polystyrene ball was incubated with test serum and, after washing, with antihuman IgG gamma-chain Fab'-peroxidase conjugate. Usefulness of the immune-complex-transfer enzyme immunoassay was demonstrated using 271 serum samples.     

More sensitive and simpler immune complex transfer enzyme immunoassay for antithyroglobulin IgG in serum

A more sensitive and simpler immune complex transfer enzyme immunoassay for antithyroglobulin IgG in serum and its use for the measurement of antithyroglobulin IgG in healthy subjects and patients with thyroid diseases are described. Antithyroglobulin IgG in test serum was reacted simultaneously with dinitrophenylthyroglobulin and thyroglobulin-beta-D-galactosidase conjugate. The complex formed of antithyroglobulin IgG, dinitrophenyl thyroglobulin, and thyroglobulin-beta-D-galactosidase conjugate was trapped onto two polystyrene balls coated with affinity-purified rabbit (antidinitrophenyl bovine serum albumin) IgG. The polystyrene balls were washed to eliminate nonspecific IgG in the test serum, and the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to two polystyrene balls coated with affinity-purified rabbit (anti-human IgG gamma-chain) IgG. beta-D-Galactosidase activity bound to the polystyrene balls was assayed by fluorimetry using 4-methylumbelliferyl-beta-D-galactoside as substrate. As compared with the previous immune complex transfer enzyme immunoassay, the procedure was simplified by reducing one incubation step and one washing step, and the detection limit of antithyroglobulin IgG in serum (0.1 microgram/liter) was lowered 100-fold. More careful and extensive examination than in a previous study revealed the presence of antithyroglobulin IgG in a large proportion of healthy subjects and in all patients with Graves' disease and chronic thyroiditis.     

Ultrasensitive immune complex transfer enzyme immunoassay of HIV-1 p24 antigen with less serum interference using 2,4-dinitrophenyl-anti-HIV-1 p24 IgG and indirectly immobilized (anti-2,4-dinitrophenyl group) Fab..

In the immune complex transfer enzyme immunoassay previously reported, the immune complex consisting of 2,4-dinitrophenyl-biotinyl-bovine serum albumin-affinity-purified rabbit anti-HIV-1 p24 Fab' conjugate, HIV-1 p24 antigen and monoclonal mouse anti-HIV-1 p24 Fab'-beta-D-galactosidase conjugate was trapped on polystyrene beads coated directly with affinity-purified (anti-2,4-dinitrophenyl group) IgG and was transferred to polystyrene beads coated with biotinyl-bovine serum albumin and streptavidin. The serum volume used was limited to 10 microL due to serious serum interference, and the detection limit of HIV-1 p24 antigen was 240 fg/mL serum. In the present study, HIV-1 p24 antigen was incubated simultaneously with 2,4-dinitrophenyl-affinity-purified rabbit anti-HIV-1 p24 IgG and monoclonal mouse anti-HIV-1 p24 Fab'-beta-D-galactosidase conjugate in the presence of excess nonspecific rabbit IgG. The immune complex of the three components formed was trapped on polystyrene beads coated successively with biotinyl-bovine serum albumin, streptavidin and biotinyl-affinity-purified (anti-2,4-dinitrophenyl group) Fab'. After washing, the immune complex was eluted from the polystyrene beads with excess epsilonN-2,4-dinitrophenyl-L-lysine and transferred to polystyrene beads coated with affinity-purified goat (antirabbit IgG) IgG.The serum volume used was increased to 90 microL with only slight serum interference, and the detection limit of HIV-1 p24 antigen was lowered 9-fold to 26 fg/mL serum.     

Anti-HTLV-I IgG in urine detected by sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using a synthetic peptide,Cys-env gp46(188-224), as antigen

Antibody IgG to human T-cell leukemia virus type I (HTLV-I) in urine was detected by a sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using a synthetic peptide, Cys-env gp46(188–224), as antigen, the sensitivity and specificity of which were 100 and 98.5%, respectively, using serum samples. Anti-HTLV-I IgG in urine was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin–Cys-env gp46(188–224) conjugate and Cys-env gp46(188–224)-β-D -galactosidase (Escherichia coli) conjugate. The complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, eluted with ?N-2,4-dinitrophenyl-L -lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG γ-chain) IgG. Finally, bound β-D -galactosidase activity was assayed by fluorometry. Thirty-one urine samples from seropositive subjects and 100 urine samples from seronegative subjects were tested. The sensitivity and specificity were 87 and 100%, respectively, with unconcentrated urine samples and 94 and 100%, respectively, with approximately 10-fold concentrated urine samples. These results were superior to those by the conventional ELISA and gelatin particle agglutination test. © 1994 Wiley-Liss, Inc.     

Detection of anti-ovalbumin IgG in serum by immune complex transfer enzyme immunoassay

An immune complex transfer enzyme immunoassay for anti-ovalbumin IgG in serum is described. Serum-specific antibody was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-ovalbumin conjugate and ovalbumin-peroxidase conjugate. The complex formed by the three components was trapped onto polystyrene balls coated with anti-2,4-dinitrophenyl group IgG, eluted with epsilonN-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with anti-human IgG-gamma-chain. Bound peroxidase activity was determined by fluorometry. This enzyme immunoassay was 300- to 1,000-fold more sensitive and more reliable than the enzyme-linked immunosorbent assay (ELISA). Anti-ovalbumin IgG was detected in 100% of healthy subjects using this method while only 14% were detected by ELISA.     

Detection of antibody IgG to HIV-1 in urine by ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant p24 as antigen for diagnosis of HIV-1 infection

Anti-HIV-1 IgG in urine was detected by an ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant p24 gag protein (p24) of HIV-1 as antigen and β-D-galactosidase from Escherichia coli as label. Anti-HIV-1 IgG in urine was reacted simultaneously with 2, 4-dinitrophenyl-bovine serum albumin-recombinant p24 conjugate and recombinant p24-β-D-galactosidase conjugate. The complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2, 4-dinitrophenyl group) IgG, eluted with ?N-2, 4-dinitrophenyl-L-lysine, and transferred to polystyrene balls coated with affinity-purified (anti-human IgG γ-chain) IgG. Bound γ-D-galactosidase activity was assayed by fluorometry. This assay was at least 3, 000-fold more sensitive than conventional methods. The lowest signal among 49 asymptomatic carriers was 3.1-fold higher than the highest nonspecific signal among 100 seronegative subjects. The sensitivity and specificity were both 100%. The positivity could be confirmed by preincubation of urine samples with excess of the antigen. Thus, this assay would be a powerful tool for detecting IgG antibody to HIV-1 in urine. © 1994 Wiley-Liss, Inc.     

Rapid and ultrasensitive enzyme immunoassay (thin aqueous layer immune complex transfer enzyme immunoassay) for HIV-1 p24 antigen

The immune complex transfer enzyme immunoassay for HIV-1 p24 antigen was performed in three different ways (in the present immunoassays I, II, and III) within much shorter periods of time than previously reported. In the present (simultaneous) immunoassay I, p24 antigen was incubated simultaneously with 2,4-dinitrophenyl-biotinyl-bovine serum albumin-affinity-purified rabbit anti-p24 Fab′ conjugate and monoclonal mouse anti-p24 Fab′-β-D -galactosidase conjugate in a total volume of 19 μL for 15 min to form the immune complex comprising the three components. The reaction mixture was incubated with a polystyrene bead of 6.35 mm in diameter coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG for 5 min to trap the immune complex. After washing, the polystyrene bead was incubated with 35 μL of ϵN-2,4-dinitrophenyl-L -lysine for 15 min to elute the immune complex (the first eluate) and, after removing the first eluate, with an additional 35 μL of ϵN-2,4-dinitrophenyl-L -lysine for 1 min (the second eluate). The first and second eluates were incubated with a polystyrene test tube (12 × 75 mm) coated with streptavidin for 15 min. In the present (sequential) immunoassay II, a polystyrene bead of 6.35 mm in diameter successively coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG and 2,4-dinitrophenyl-biotinyl-bovine serum albumin-affinity-purified rabbit anti-p24 Fab′ conjugate was incubated with p24 antigen in a total volume of 20 μL for 5 min and subsequently with monoclonal mouse anti-p24 Fab′-β-D -galactosidase conjugate in a volume of 5 μL for 20 min. The immune complex formed on the polystyrene bead was transferred to a polystyrene test tube coated with streptavidin as described above. In the present (sequential) immunoassay III, p24 antigen was incubated with monoclonal mouse anti-p24 Fab′-β-D -galactosidase conjugate in a total volume of 19 μL for 10 min and with a polystyrene bead of 6.35 mm in diameter coated successively with affinity-purified (anti-2,4-dinitrophenyl group) IgG and 2,4-dinitrophenyl-biotinyl-bovine serum albumin- affinity-purified rabbit anti-p24 Fab′ conjugate for 20 min. The immune complex formed on the polystyrene bead was transferred as described above. The incubations were performed at room temperature either by shaking the polystyrene beads (one/assay) and the reaction mixtures in styrol test tubes (13.3 × 54 mm and 2.1 g) so as to randomly rotate the polystyrene beads or by rotating the polystyrene test tubes (12 × 75 mm) containing the reaction mixtures, so that small drops (19 to 70 μL) of the reaction mixtures evenly contacted all parts of the solid phase surfaces during the incubations (although they contacted only small parts of the solid phase surfaces at a time) to continuously mix thin aqueous layers covering the solid phase surfaces with the rest of the reaction mixtures. (Therefore, these immunoassays are called thin aqueous layer immunoassays.) The detection limits of p24 antigen by 1 hr assay of bound β-D -galactosidase activity in the present immunoassays I, II, and III were 0.1, 0.2 and 0.1 amol/assay, respectively, and were slightly higher than or equal to that by the previously reported immune complex transfer enzyme immunoassay, in which the immune complex was formed for 4 hr, was trapped for 16 hr, and was transferred for 3 hr followed by 1-hr assay of bound β-D -galactosidase activity. By 20-hr assay of bound β-D -galactosidase activity, the detection limit of p24 antigen was further lowered to 10 zmol/assay in the present (simultaneous) immunoassay I and to 3 zmol/assay in the present (sequential) immunoassay III. However, the nonspecific reaction(s) with serum samples from HIV-1 seronegative subjects hampered the improvement of the detection limit by 20-hr assay of bound β-D -galactosidase activity. J. Clin. Lab. Anal. 12:205–212, 1998. © 1998 Wiley-Liss, Inc.     

Measurement of anti-thyroglobulin IgG in serum by novel and sensitive immune complex transfer enzyme immunoassay

Anti-thyroglobulin IgG in human serum was measured by a novel and sensitive immune complex transfer enzyme immunoassay. Anti-thyroglobulin IgG in human serum was reacted with dinitrophenyl thyroglobulin, and the complex formed between human anti-thyroglobulin IgG and dinitrophenyl thyroglobulin was trapped onto an affinity-purified rabbit (anti-dinitrophenyl bovine serum albumin) IgG-coated polystyrene ball. The polystyrene ball was washed to eliminate most nonspecific IgG in test serum, and the complex was eluted from the polystyrene ball, to which nonspecific IgG had been adsorbed, with dinitrophenyl-L-lysine and transferred to a clean polystyrene ball coated with rabbit anti-thyroglobulin IgG. The amount of human anti-thyroglobulin IgG in the complex on the rabbit anti-thyroglobulin IgG-coated polystyrene ball was estimated using rabbit (anti-human IgG gamma-chain) Fab'-horseradish peroxidase conjugate. The present enzyme immunoassay was 1,000 to 3,000-fold more sensitive than the conventional enzyme immunoassay, in which a human thyroglobulin-coated polystyrene ball was incubated with serum containing human anti-thyroglobulin IgG and, after washing, with rabbit (anti-human IgG gamma-chain) Fab'-horseradish peroxidase conjugate. By the present enzyme immunoassay, anti-thyroglobulin IgG was demonstrated in about 10% of healthy subjects and in all patients with Graves' disease and chronic thyroiditis. The principle of the present method may make it possible to sensitively measure other autoantibodies including anti-thyroid peroxidase and anti-thyrotropin receptor antibodies to aid diagnosis of thyroid diseases.     

Novel and ultrasensitive noncompetitive enzyme immunoassay (hetero-two-site complex transfer enzyme immunoassay) for alpha-human atrial natriuretic peptide.

A novel and ultrasensitive noncompetitive enzyme immunoassay (hetero-two-site complex transfer enzyme immunoassay) for alpha-human atrial natriuretic peptide (alpha-hANP) in plasma is described. alpha-hANP was biotinylated using N-hydroxysuccinimidobiotin and trapped onto an anti-alpha-hANP [6-28] IgG-coated polystyrene ball. After washing, biotinylated alpha-hANP was eluted from the polystyrene ball with HCI and was reacted with 2,4-dinitrophenyl-fluorescein-bovine serum albumin-disulfide-rabbit anti-alpha-hANP [6-28] IgG conjugate. The complex formed was trapped onto (anti-2,4-dinitrophenyl group) IgG-coated polystyrene balls and, after washing, reacted with avidin-beta-D-galactosidase conjugate. The polystyrene balls were washed, and the complex of the three components was eluted with epsilon N-2, 4-dinitrophenyl-L-lysine and transferred to anti-fluorescein IgG-coated polystyrene balls. After washing, the complex was released from the polystyrene balls by reduction with 2-mercaptoethylamine and transferred to (anti-rabbit IgG) IgG-coated polystyrene balls. beta-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. The detection limit of alpha-hANP [1-28] was 3 fg (1 amol)/tube. Interference by plasma proteins was eliminated by separation of peptides from proteins using a molecular sieve. The assay range of plasma alpha-hANP [1-28] was 0.04-120 ng/L, and plasma levels of hANP in healthy subjects (11-56 ng/L) were measured without concentration.     

Ultrasensitive and rapid enzyme immunoassay (thin aqueous layer immune complex transfer enzyme immunoassay) for antibody IgG to HIV-1 p17 antigen

The immune complex transfer enzyme immunoassay for antibody IgG to HIV-1 p17 antigen was performed in two different ways (the present immunoassays I and II) within shorter periods of time than previously reported. In the present (simultaneous) immunoassay I, antibody IgG to HIV-1 p17 antigen in 10 μL of serum samples was incubated simultaneously with 2,4-dinitrophenyl-maltose binding protein-recombinant p17(rp17) fusion protein and rp17-β-D -galactosidase conjugate in a total volume of 22 μL for 10 min to form the immune complex comprising the three components. The reaction mixture was incubated with a polystyrene bead of 6.35 mm in diameter coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG for 5 min in a styrol test tube (13.3 × 54 mm and 2.1 g) to trap the immune complex. After washing, the polystyrene bead was incubated with 30 μL of ϵN-2,4-dinitrophenyl-L -lysine solution in a polystyrene tube (12 × 75 mm) coated with affinity-purified (antihuman IgG γ-chain) IgG for 10 min to transfer the immune complex. In the present (sequential) immunoassay II, a polystyrene bead of 6.35 mm in diameter coated successively with affinity-purified (anti-2,4-dinitrophenyl group) IgG and 2,4-dinitrophenyl-maltose binding protein-rp17 fusion protein was incubated in a styrol test tube (13.3 × 54 mm and 2.1 g) sequentially with antibody IgG to HIV-1 p17 antigen in 10 μL of serum samples in a total volume of 16 μL for 5 min and subsequently with rp17-β-D -galactosidase conjugate in a volume of 10 μL for 5 and 10 min. The immune complex formed on the polystyrene bead was transferred to a polystyrene tube coated with affinity-purified (antihuman IgG γ-chain) IgG for 5 and 10 min in the same way as in the present immunoassay I. During the incubations, the styrol test tubes containing the polystyrene beads and reaction mixtures were shaken, and the polystyrene test tubes were rotated with shaking, so that the polystyrene beads were rotated randomly, and small drops (16 to 30 μL) of the reaction mixtures evenly contacted all parts of the solid phase surfaces during the incubations, though only small parts of the solid phase surfaces were contacted at one time. The intent was to continuously mix thin aqueous layers of the reaction mixtures covering the solid phase surfaces with the rest of the reaction mixtures. (Therefore, these immunoassays were called thin aqueous layer immunoassays.) β-D -Galactosidase activity bound to the polystyrene tubes was assayed by fluorometry for 30 and 60 min. The present immunoassays I and II, in which only 15 to 25 min were used for the immunoreactions, were as sensitive if not more so than the previous immune complex transfer enzyme immunoassay requiring 150 min for the immunoreactions. In these earlier immunoreactions, the immune complex comprising the three components formed by 30 min incubation was trapped onto two polystyrene beads (3.2 mm in diameter) coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG for 60 min, and was then transferred to two polystyrene beads (3.2 mm in diameter) coated with affinity-purified (antihuman IgG γ-chain) IgG for 60 min in a total volume of 150 μL. Furthermore, the present (sequential) immunoassay II (and probably I) could become approximately 10 times more sensitive by assaying bound β-D -galactosidase activity for a longer period of time (10 h), since β-D -galactosidase activity, bound nonspecifically in the presence of serum samples from HIV-1 seronegative subjects, was considerably low. J. Clin. Lab. Anal. 12:179–189, 1998. © 1998 Wiley-Liss, Inc. No abstract.     

Novel enzyme immunoassay (Immune Complex Transfer Enzyme Immunoassay) for anti-thyroglobulin IgG in human serum

A novel enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG in human serum is described. Anti-thyroglobulin IgG in human serum was reacted with dinitrophenyl thyroglobulin, and the complex formed between anti-thyroglobulin IgG and dinitrophenyl thyroglobulin was trapped onto an affinity-purified rabbit (anti-dinitrophenyl bovine serum albumin) IgG-coated polystyrene ball. After eliminating nonspecific IgG in test serum by washing, the complex was eluted from the polystyrene ball with dinitrophenyl-L-lysine and transferred to a clean polystyrene ball coated with rabbit anti-thyroglobulin IgG. The amount of human anti-thyroglobulin IgG in the complex on the rabbit anti-thyroglobulin IgG-coated polystyrene ball was estimated using rabbit (anti-human IgG 7-chain) Fab'-horse-radish peroxidase conjugate. The present enzyme immunoassay was 1,000–3,000-fold more sensitive than the conventional enzyme immunoassay, in which a thyroglobulin-coated polystyrene ball was incubated with serum containing anti-thyroglobulin IgG and subsequently with rabbit (anti-human IgG 7–chain) Fab'-horseradish peroxidase conjugate. By the present enzyme immunoassay, anti-thyroglobulin IgG was demonstrated in all patients with Graves' disease and chronic thyroiditis.     

Sensitive time-resolved fluorimetric immune-complex-transfer immunoassay for antithyroglobulin IgG in serum

A sensitive time-resolved fluorimetric immune-complex-transfer immunoassay for antithyroglobulin IgG in serum is described. Antithyroglobulin IgG in test serum was reacted with dinitrophenyl europium ion-labeled thyroglobulin. The complex formed of antithyroglobulin IgG and dinitrophenyl europium ion-labeled thyroglobulin was trapped onto two polystyrene balls coated with affinity-purified rabbit antidinitrophenyl bovine serum albumin IgG. The polystyrene balls were washed to eliminate nonspecific IgG in the test serum, and the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to two polystyrene balls coated with affinity-purified rabbit antihuman IgG gamma-chain IgG. Europium ion bound to the polystyrene balls was measured by time-resolved fluorimetry. Antithyroglobulin IgG was demonstrated in all patients with Graves' disease and all patients with chronic thyroiditis. This immunoassay was more sensitive than the conventional enzyme immunoassay and less time-consuming than the previously described immune-complex-transfer enzyme immunoassays, although there were larger assay variations.     

Ultrasensitive and more specific enzyme immunoassay (immune complex transfer enzyme immunoassay) for p24 antigen of HIV-1 in serum using affinity-purified rabbit anti-p24 Fab′ and monoclonal mouse anti-p24 Fab′

Previously, an ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for p24 antigen of HIV-1 was developed. The immune complex comprising 2,4-dinitrophenyl-biotinyl-bovine serum albumin-rabbit anti-p24 Fab′ conjugate, p24 antigen, and rabbit anti-p24 Fab′-β-D-galactosidase conjugate was trapped onto polystyrene beads coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, was eluted with ϵN-2,4-dinitrophenyl-L-lysine, and was transferred to polystyrene beads coated with streptavidin. β-D-Galactosidase activity bound to the streptavidin-coated polystyrene beads was assayed by fluorometry. This assay was highly sensitive. However, bound β-D-galactosidase activity had to be assayed for a long time (20 h), and the nonspecific signal was observed in 5% serum samples from subjects with low risk of HIV infection. In the present study, the assay time for bound β-D-galactosidase activity was shortened to 2.5 h by using 2,4-dinitrophenyl-biotinyl-bovine serum albumin-affinity-purified rabbit anti-p24 Fab′ conjugate and affinity-purified rabbit anti-p24 Fab′-β-D-galactosidase conjugate. Furthermore, the nonspecific signal was found to increase with increasing periods of time for storage of serum samples at -20°C, and this increase was prevented without prolongation of the assay time for bound β-D-galactosidase activity and without loss of the sensitivity by substituting monoclonal mouse anti-p24 Fab′-β-D-galactosidase conjugate for affinity-purified rabbit anti-p24 Fab′β-D-galactosidase conjugate. © 1996 Wiley-Liss, Inc.     

Use of indirectly immobilized recombinant p17 antigen for detection of antibodies to HIV-1 by enzyme immunoassay

Recombinant HIV-1 p17 antigen (rp17) and maltose binding protein-rp17 fusion protein (MBP-rp17) were immobilized in different ways: rp17 and MBP-rp17 were immobilized directly onto polystyrene beads by physical adsorption, and biotinyl-rp17, biotinyl-MBP-rp17, and 2,4-dinitrophenyl (DNP)-MBP-rp17 were immobilized indirectly onto polystyrene beads, which had been coated with streptavidin alone, with biotinyl-bovine serum albumin and streptavidin and with (anti-2,4-dinitrophenyl group) IgG. These immobilized antigens were tested by incubation with diluted serum from an HIV-1 seropositive subject in the absence and presence of serum from HIV-1 seronegative subjects and, after washing, with rp17 beta-D-galactosidase conjugate. Higher positive signals (fluorescence intensities for bound -beta-D-galactosidase activity) and less serum interference were obtained with indirectly immobilized antigens than with directly immobilized ones. Enzyme immunoassay using biotinyl-MBP-rp17 indirectly immobilized onto polystyrene beads, which had been coated sequentially with biotinyl-bovine serum albumin and streptavidin, was approximately 1,000-fold more sensitive than that using directly immobilized rp17 antigen and Western blotting for p17 band. This enzyme immunoassay indicated positivity in HIV-1 seroconversion serum panels as early as or even earlier than conventional methods and considerably earlier than Western blotting for HIV-1 p17 band. In addition, the sensitivity was further improved approximately 10-fold by incubation with shaking for immunoreactions and by increase of both the number of polystyrene beads and the volume of serum samples used per assay.