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.

Detection of Kaposi's sarcoma-associated herpesvirus in oral and genital secretions of Zimbabwean women.

Kaposi's sarcoma-associated herpesvirus (KSHV) in oral and genital secretions of women may be involved in horizontal and vertical transmission in endemic regions. Nested polymerase chain reaction assays were used to detect KSHV DNA sequences in one-third of oral, vaginal, and cervical specimens and in 42% of peripheral blood mononuclear cell (PBMC) specimens collected from 41 women infected with human immunodeficiency virus type 1 who had Kaposi's sarcoma (KS). KSHV DNA was not detected in specimens from 100 women without KS, 9 of whom were seropositive for KSHV. A positive association was observed between KSHV DNA detection in oral and genital mucosa, neither of which was associated with KSHV DNA detection in PBMC. These data suggest that KSHV replicates in preferred anatomic sites at levels independent of PBMC viremia. Detection of genital-tract KSHV only among relatively immunosuppressed women may provide an explanation for infrequent perinatal transmission of KSHV.

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.

The effect of potential investment expansion and hot strength on the fit of full crown castings made with phosphate-bonded investment.

In an earlier investigation, it was shown that when full crowns are cast in gypsum-bonded investments, their relative inaccuracy is affected by both the investment's potential expansion and its hot strength. This study repeated the earlier one, but used a high-melting gold alloy and two phosphate-bonded investments. The investments were used under conditions which gave a range of potential expansions and hot strengths. Casting inaccuracies were determined both diametrally and axially. All castings showed distortion, which varied under the different conditions. All were oversized axially, by amounts varying from + 0.8% to +2.3%. Diametral inaccuracies ranged from -0.2% to +0.7%. Investment expansion had a strong effect on axial inaccuracy, but a negligible effect on diametral inaccuracy. Conversely, hot strength had a strong effect on diametral inaccuracy, but only a very weak effect on axial inaccuracy. With phosphate-bonded investments, both potential expansion and hot strength are important parameters of relative casting inaccuracy. In combination, these properties showed very strong correlations with both diametral and axial inaccuracies. The observed distortions were the result of anisotropic mould expansion and anisotropic alloy shrinkage. The best fit, and least distortion, occurred with an investment setting under dry conditions.

Optimization, assessment, and proposed use of a direct nested reverse transcription-polymerase chain reaction protocol for the detection of hepatitis C virus.

OBJECTIVES: To compare the performance of reverse transcription followed by the polymerase chain reaction (RT-PCR), without RNA purification, with the performance of classic protocols. STUDY DESIGN/METHODS: Direct and classic techniques were used to test three groups of samples: six hepatitis C virus (HCV) seroconversion panels (n = 90), a HCV RNA reference panel (n = 26), and serial dilutions of four HCV-positive sera (n = 24). These methods were then applied sequentially through a clinical diagnostic algorithm to test 268 samples from high-risk patients. RESULTS: For the three groups of samples, we found a 94% concordance between direct and purified RT-PCR methods. For the detection of HCV RNA in clinical samples, sensitivity was maximized and cost minimized using both protocols according to the proposed algorithm. CONCLUSIONS: The direct PCR method is reliable, sensitive, and can result in time and cost savings. The suggested testing algorithm can enhance sensitivity and time savings for populations with a high prevalence of infection.

An epidemiological survey of SIDS in the Sydney metropolitan area.

Records of 1049 cases of Sudden Infant Death Syndrome (SIDS) (100%) in the Sydney metropolitan area (SMA) from 1980 to 1989 were analysed in relation to ambient temperature, geographical distribution and socio-economic scale. The SIDS rate varied between eastern and western Sydney and between statistical subdivisions; it peaked sharply in July, coinciding with the monthly mean minimum daily temperature (MMMDT; 6.5 and 5.4 degrees C, respectively). The inverse linear relationship between the SIDS rate and the MMMDT for the regions and the subdivisions was highly significant (P < 0.001). The SIDS rate showed a significant inverse linear relationship to two socio-economic scales (allotment and house value) for 82 of the 87 suburbs (94%) of the SMA. Temperature, indicative of cold weather, was the major factor determining SIDS rates, and this, together with socio-economic factors, largely explains the observed geographical distribution of SIDS rates in the SMA.