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Du Pont De Nemours perfected a new enzyme immunoassay for the screening of anti-HIV 1 antibodies, characterized by its rapidity: 2 hours of incubation, when the normal procedure needed 3 hours 30 minutes of incubation. We tested with the normal procedure and the shortened one 4,025 randomly selected blood donors. 55 samples of the SNTS panel and 10 sera representing the Western-Blot reference panel of the "Retrovirus" study group of the SNTS. We can say that shortening the incubation time results in certain advantages opposite the previous procedure: time saving (1 hour 30 minutes); improved specificity: the rate of false positive, 0.37% with the normal method, drops to 0.07% with the short one; good sensitivity, since all the individual positive samples were detected but it seems slightly less sensitive than the normal method for the diluted positive samples.

We tested the Wellcozyme anti-HTLV III kit on: 600 blood donors fresh sera, simultaneously tested by Elavia (Diagnostics Pasteur) or Vironostika (Organon); 20 plasmas, known to be anti-HIV negative; 22 sera, already labelled, and a panel of 10 specimens from the "Retrovirus" study group of the French National Society of Blood Transfusion, also tested by Elavia, Vironostika, Abbott HTLV III EIA and by two confirmatory tests: Immuno-blot (Diagnostics Pasteur) and Abbott confirmatory test. The Wellcome kit is, at present, the only one to use a competitive Elisa method and not to require any sample predilution. The method is easy to perform, rapid (results in 1 h 30 time) and it tests as well serum as plasma. No interferences have been observed from high lipid concentrations or strong hemolysis on the Elisa reaction. The performances of the Wellcozyme test are satisfactory. We did not find any "false positive" result. But the study shows that this kit is not sensitive enough for the detection of anti-P25 antibodies, which appear on the beginning of seroconversion, unless the "grey range" is extended: the Wellcome Laboratories have just made this recommendation.

The authors present the results of a study comparing the detection of HbSAg by enzyme immunoassay using the following three different commercial kits and their corresponding apparatus: Auszyme II, Quantum II from Abbott; Enzygnost micro Elisa, Elisa Processor from Behring; Hepanostika, washer and reader micro Elisa system from Organon. The purpose of the study is to determine the sensitivity and specificity of the reaction and the extent of automation of this method. The sensitivity and specificity of the 3 kits are compared with those of a reference technique, the radioimmunoassay Ausria II, Abbott. The sensitivity of Auszyme II is equivalent to that of Ausria II and is approximately 0.2 mg/ml. The other two kits are somewhat less sensitive. The proportion of false negative is less than 1%, but with all 3 kits it is necessary to verify a negative result. The results of this study confirm the high level of sensitivity and specificity of the enzyme immunoassay for the detection of HbSAg in the serum or plasma of blood donors. This technique therefore offers an alternate method of HbSAg detection to laboratories which cannot or prefer not to use a radioimmunoassay.