A comparison of four enzyme immunoassays for the simultaneous detection of HIV-1- and HIV-2-specific antibody.

The performance of four HIV 1 and 2 combined assays has been compared with current type-specific assays using three panels of sera. The first panel comprised single samples from 19 HIV-1-infected persons; the second panel comprised 19 sera from 16 HIV-2-infected persons. Samples from both these panels were titrated across interpolated end points of detectability. The third panel comprised sera from 5200 consecutive blood donors. The four combined assays, manufactured by Abbott Laboratories, Behring Laboratories, Diagnostics Pasteur and Wellcome Diagnostics Laboratories detected all anti-HIV-1 sera at high dilution; the immunometric assay from Wellcome was particularly proficient. All assays were broadly similar in their ability to detect sera from recently infected persons. The same assays were also effective in detecting anti-HIV 2 in sera both from seropositive individuals and from a single recently-infected person, though none was as sensitive as an inhouse competitive EIA. When used for donor screening the repeat reactive rates for donors negative for HIV 1 and 2 antibodies ranged between 1.80% for Elavia Mixt from Pasteur, 0.27% Abbott combined and 0.15% for the Wellcome combined assays.

Gelatin particle agglutination assay for HIV antibodies: a rapid, economical modification with increased sensitivity.

Modification of a commercial gelatin particle agglutination assay for anti-HIV reduces the test time to 30 min, increases the sensitivity sevenfold without any prozoning, and maintains specificity while cutting the cost of the test by 90%. The modification involves a tenfold dilution of the gelatin particles, which are added to a dilution of test serum in a 'V' well standard microplate. After incubation, plates are centrifuged briefly and allowed to stand at an inclination of 70 degrees until positive and negative reactions are clearly distinguishable within approximately 15 min.

Influence of Trypanosoma infection on the formation of E, EA, and EAC rosettes with peripheral blood lymphocytes from calves.

Peripheral blood lymphocyte (PBL) from calves infected with T. brucei and T. congolense or T. congolense alone were tested for their capacity to form E, EA, and EAC rosettes. The results obtained indicate that early in the infection a slight increase in the number of T and B cells has occurred as indicated by the increase in E and EAC rosette formation. At the same time EA rosette forming cells were also increased and persisted during the whole time of the infection. The EA rosette forming cells were more likely null cells, because later in the infection neither E nor EAC rosette forming cells showed any increase.

Screening blood donors for high titre antibody to herpes varicella-zoster.

As a method of increasing supplies of varicella-zoster immunoglobulin, semi-automated screening of blood donors for high titre complement-fixing antibody was initiated. This was compared with the previously used method of donor selection based on a history of varicella or zoster in the past 6 months. About one-third of the "history" donors had titres of greater than or equal to 1 in 64 and generally these levels declined rapidly. In contrast, although only 1.1% of donors in random screening had antibody titres greater than or equal to 1 in 64, these levels usually remained high during repeated donation, enabling the production of pools entirely composed of high titre plasma packs.

Diazoniobenzenesulfonate as marker for cell surface proteins: study of the surface coat of Trypanosoma congolense.

It is possible to label selectively the surface coat of Trypanosoma congolense with radioactive sulfanilic acid diazonium salt. As demonstrated by both sodium dodecylsulfate polyacrylamide gel electrophoresis and isoelectric focusing, radioactivity is incorporated into only one protein, which has a molecular weight of 57 000 and an isoelectric point of 6.25. This indicates that the surface coat of T. congolense is a homogeneous layer, composed of molecules of one type of protein.