Characteristics of a Population Volunteering for Human Immunodeficiency Virus Immunization

Abstract

A total of 166 volunteers for an AIDS vaccine study (Vaxsyn, baculovirus produced recombinant GP160; MicroGeneSys Inc, West Haven, Connecticut, USA) were interviewed and examined. Blood was collected for routine laboratory testing as well as T-cell counts, HIV ELISA (EIA), Western blot (WB) and p24 Ag. Eighty-five men (mean age 22.2 years, range 18-42) and 81 women (mean age 23.9 years, range 17-50) volunteered; 130/166 (78%) were university students. Most had learned of the study from news media (55%), friends or workplace (37%). The most common causes for exclusion were the presence of indeterminate WB (26.5%) or a change of mind after the initial interview (24%). Other causes were abnormal cell count and differential (7.2%), elevated alanine aminotransferase (3.6%), positive hepatitis B antibody (3.6%), abnormal urinalysis (3.4%), recent venereal disease (3.0%), T4 cell count less than 400 (1.9%), abnormal chest X-ray (1.7%), recognized high-risk behaviour (1.7%), multiple sex partners (1.2%), positive rapid plasma reagin test (1.2%), failure to meet age criteria (1.2%), unable to be available for entire study (1.2%), abnormal physical examination (0.6%) and positive p24 Ag (0.6%). No volunteers had positive EIA, but 14.5% had more than one reason for exclusion. Even in a community with low prevalence for HIV, a large majority of healthy heterosexual volunteers can be expected to be ineligible for enrollment in HIV vaccine trials. An average of 4.8 volunteers were screened for each of 12 vaccinees chosen.

Frequency, Causes, and New Challenges of Indeterminate Results in Western Blot Confirmatory Testing for Antibodies to Human Immunodeficiency Virus

“…Based on the finding, Dock et al suggested excluding individuals with EIA-positive results but atypical Western blot findings from the donor pool (25). On the other hand, indeterminate results were also found to exist even in a community with low prevalence with no apparent involvement of any risk factors for HIV (104). A separate study of donors with initial negative screening results revealed that WBi patterns were common in donors and their recipients and suggested that they were not correlated with the presence of HIV-1 or transmission of HIV-1 from donor to recipient (30).…”

“…WBi results are neither new nor unique to HIV testing (49,67,75). In some earlier studies, researchers looked into various cohorts, including HIV initial-screen-positive subjects, healthy volunteers for vaccine trials, healthy blood donors who had negative initial-screen results, and their respective recipients (25,30,58,104). While some of the indeterminate results might be at least partially related to variability in the performance of earlier products (30,58), others were found to be fairly consistent and reproducible (25).…”

Evaluation of Chiron HIV-1/HIV-2 recombinant immunoblot assay

“…The causes of indeterminate results, although not clearly understood, have been associated with contaminating cellular antigens on viral lysatebased blot strips, autoantibodies, pregnancy, elevated bilirubin levels, and in vitro hemolysis (4). Approximately 20 to 33% of HIV type 1 (HIV-1) enzyme immunoassay (EIA)-negative serum samples have indeterminate results by Western blotting (9,15,18). In addition, between 4 and 20% of serum samples that are repeatedly reactive by the HIV-1 EIA have indeterminate Western blot assay results (3,6,14,17).…”