Evaluation of oral fluid enzyme immunoassay for confirmation of a positive rapid human immunodeficiency virus test result.

The CDC recommends that a reactive rapid human immunodeficiency virus (HIV) test be confirmed with an approved supplemental test; the performance of an intermediate enzyme immunoassay (EIA) is optional. In support of this recommendation, it was found that of 1,431 reactive rapid HIV test results, 2 (0.1%) had false-negative oral fluid Western blot results and both had false-negative EIA results.

Assessment of the performance of a rapid, lateral flow assay for the detection of antibodies to HIV.

Rapid HIV assays have recently been shown to have important applications for various testing situations, including early identification of infected individuals, to allow intervention strategies in a clinically relevant time frame. A rapid, lateral flow, HIV-1/2/O assay was evaluated using 2,000 serum or plasma samples from various risk groups and geographic locations, including HIV-1 and HIV-2 positive sera from five countries. Two U.S. Food and Drug Administration (FDA)-licensed screening assays and a FDA-licensed confirmatory assay were used as reference tests. The rapid assay exhibited a near-perfect sensitivity (99.2%) and an excellent specificity (99.9%). Moreover, its analytical sensitivity was found to be better than most FDA-licensed enzyme-linked immunosorbent assays (ELISAs), detecting infection at the same time as the most sensitive ELISA in two of five seroconversion panels, and at the same time or earlier than four of five ELISAs in all five panels. We conclude that this rapid assay is a suitable test for the detection of HIV infection that could be particularly useful in developing countries where facilities may not support the use of instrumentation.

The incidence of GB virus C / hepatitis G virus infection in Brazilian patients who received blood transfusion during cardiac surgery.

The incidence of GBV-C/hepatitis G virus (GBV-C/HGV) infection after blood transfusion is unknown in Brazil. Many studies have so far addressed its relationship with blood transfusion, but its association with liver disease was not confirmed. A prospective study was carried out between 1996 and 1999 in Rio de Janeiro. Ninety three patients who received blood transfusion during cardiac surgery were followed for six months and blood samples were drawn before and after surgery to determine antibodies to GBV-C/hepatitis G virus (anti-HGenv) using a step sandwich immunoassay and GBV-C/HGV-RNA using reverse transcriptase polymerase chain reaction. The alanine aminotransferase (ALT) levels were serially determined as well as clinical data compiled related to hepatitis. Prior to surgery, anti-HGenv was present in 35.5% (33/93) of patients and 4.3%(4/93) were found to be viremic. Seroconversion following transfusion was observed in 9 patients and 4 additional individuals became viremic for a total incidence of 23% (13/56). Six months after blood transfusion, only 4 of those nine patients previously antibody positive still had anti-HGenv detectable in serum. No patients had clinical or laboratory evidence of acute hepatitis and no correlation was found with GBV-C/HGV infection and number of blood units transfused (p = 0.37). This study highlights the importance of using both HGV-RNA PCR and anti-HGenv to accurately estimate the magnitude of GBV-C/HGV infection. The observed high prevalence and incidence rates show that this infection is common in Brazil; however, no clinical or biochemical evidence of liver disease was demonstrated in the period of study and longer longitudinal observation is needed to define any pathogenic effect.

Specifics on the refinement and application of two serological assays for the detection of antibodies to HHV-8.

BACKGROUND: Serologic assays for the detection of antibodies to human herpesvirus type 8 (HHV-8) are important for epidemiological studies and to further investigate the proposed pathogenesis of the virus in cancer. Although a variety of assays are available, a lack of optimization and standardization makes their usefulness uncertain, and may be responsible for the controversy concerning the prevalence of infection. OBJECTIVES: To refine an indirect immunofluorescent assay (IFA) for the detection of latent antibodies and a recombinant ORF 65 ELISA for the detection of lytic antibodies in order to increase their ability to differentiate individuals at higher and lower risk for HHV-8 infection. STUDY DESIGN: Sera from Kaposi's sarcoma (KS) patients and blood donors (BDs) were used to modify assay parameters in an attempt to better discriminate between the two populations. Modifications included methods of substrate fixation, incubation times, sample dilution, and antigen/conjugate concentrations. RESULTS: Optimal modifications to the latent IFA included acetone fixation of substrate, and dilution of sera to 1:64 which enhanced detection of HHV-8 antibodies from 68 to 92% in the KS population. Similarly, successful refinement of the ORF 65 ELISA to increase the signal-to-noise ratio included the use of 88 ng of ORF 65 antigen per well and serum dilutions of 1:50. Optical density-to-cut-off ratios directly correlated with titers, thereby introducing a strategy to predict antibody concentrations. The ORF 65 ELISA and the latent IFA were both able to discriminate between the two populations but with different efficiencies. CONCLUSIONS: Although neither the latent IFA nor the ORF 65 ELISA produced perfect test indices, improvement in their performances was noted following the optimization strategies. The ELISA produced better detection of antibodies to the virus than the IFA and permitted prediction of sample titers, thus improving cost and time effectiveness.