Specificity control in solid-phase enzyme immunoassay for HBsAg by one-step in situ blocking with human anti-HBs

Enzyme-linked immunosorbent assay for detection of Haemophilus influenzae type b antigen

An enzyme-linked immunosorbent assay for the detection of Haemophilus influenzae type b antigen was developed. It was able to detect purified polyribose phosphate at concentrations of greater than or equal to 1 ng/ml in cerebrospinal fluid. This was 50 times more sensitive than counterimmunoelectrophoresis with the same antiserum. The sensitivity for polyribose phosphate in urine was similar, but that in serum was about 10 times less. Nonspecific reactions were observed with blood-stained cerebrospinal fluid and some sera. These were differentiated from true positive reactions by a blocking test with unconjugated immune serum. A wide range of organisms was tested for cross-reactivity in the assay. With the exception of a protein A-rich strain of Staphylococcus aureus, they gave absorbances of < 8% of that of the homologous system. In a series of five cases of proven H. influenzae type b meningitis, the sensitivity of the assay with cerebrospinal fluid was confirmed to be at least 2(5) times greater than that of counterimmunoelectrophoresis. The results indicate that the enzyme-linked immunosorbent assay is highly sensitive and specific in detecting H. influenzae type b antigen. The necessity to perform the blocking assay on all sera limits its usefulness for the examination of these specimens. However, it should prove valuable for the detection of the antigen in cerebrospinal fluid and urine.

Results of a multicentre clinical trial of the solid-phase enzyme immunoassay for hepatitis B surface antigen

The results obtained in a multicentre clinical trial of an enzyme immunoassay (EIA) method for hepatitis B surface antigen (HBsAg) (65,451 sera tested) have demonstrated that this new test has a significantly higher sensitivity than a reversed haemagglutination test (rHA). In a part of the trial, EIA was also compared with radioimmunoassay (RIA). Only a small number of discrepant results was obtained with these two tests, indicating similar sensitivities. No definite conclusion about a difference in sensitivities could be drawn from these results. Although the specificity of the EIA screening test is lower than that of rHA and RIA, the mean percentage of false positives was 2.2% of the total number of donor samples screened. Presumptive positives in EIA were subjected to a confirmatory test based on neutralization with human antibodies to HBsAg. After elimination of false positives in EIA screening, there was excellent agreement between EIA and RIA results.

Enzyme immunoassays with special reference to ELISA techniques

In this review outlines are given on various types of enzyme immunoassay. The applications to such enzyme immunoassays, especially ELISA, are dealth with in detail. It is concluded that these techniques have high sensitivity and will be suitable in due course as routine laboratory tests.

Enzyme-immunoassay in diagnosis of hepatitis with emphasis on the detection of "e" antigen (HBeAg)

A brief survey of the application of enzyme-immunoassay (EIA) for the detection of hepatitis B surface antigen (HBsAg), hepatitis A, and their corresponding antibodies is given. The preliminary results of a similar EIA for detection of hepatitis B-related "e" antigen (HBeAg) and its antibody (anti-HBe) are reported. This EIA is much more sensitive than immunodiffusion: at least 128 times for HBeAg and at least 512 times for anti-HBe. HBsAg and its antibody do not interfere with the test. Only a few sera strongly positive for rheumatoid factor gave rise to false-positive results, as was demonstrated by a confirmatory test.