Performance evaluation of the Access HBsAg and Access HBsAg confirmatory assays on the DxI 9000 Access Immunoassay Analyzer.

Introduction: This study evaluated the clinical and analytical performances of the Access HBsAg and the Access HBsAg Confirmatory assays on the DxI 9000 Access Immunoassay Analyzer (Beckman Coulter, Inc.). Materials and methods: Diagnostic specificity and sensitivity of the Access HBsAg and Access HBsAg Confirmatory assays were evaluated by comparing the Access assays to the final HBsAg sample status determined using the Architect, PRISM, or Elecsys HBsAg assays, along with Architect or PRISM HBsAg Confirmatory assays. Imprecision, sensitivity on seroconversion panels, analytical sensitivity on WHO, and recognition of HBV variants were also evaluated. Results: A total of 7534 samples were included in the analysis (6047 blood donors, 1032 hospitalized patients, 455 positive patients' samples). Access HBsAg assay sensitivity and specificity were at 100.00% (99.19-100.0) and 99.92% (99.82-99.97), respectively. Sensitivity of Access HBsAg Confirmatory assay was 100.00% (99.21-100.0) on the 464 HBsAg positive samples. The use of a high positive algorithm for the Access HBsAg assay, wherein samples with S/CO ≥ 100.00 were considered positive without requiring repeat or confirmatory testing, was successfully evaluated with all 450 specimens with S/CO greater than 100.00 (sensitivity 100.00%; 99.19-100.0). Access HBsAg assay demonstrated good analytical performance, equivalent recognition of seroconversion panels compared to Architect assay, and an analytical sensitivity between 0.022 and 0.025 IU/mL. All HBV genotypes, subtypes and mutants were well detected without analytical sensitivity loss. Conclusion: Access HBsAg and Access HBsAg Confirmatory assays demonstrated robust performances. They provide low samples volume requirements and a simplified process, no systematic retesting for high positive samples.

Evaluation of eight different bioinformatics tools to predict viral tropism in different human immunodeficiency virus type 1 subtypes.

Human immunodeficiency virus type 1 (HIV-1) tropism can be assessed using phenotypic assays, but this is quite laborious, expensive, and time-consuming and can be made only in sophisticated laboratories. More accessible albeit reliable tools for testing of HIV-1 tropism are needed in view of the prompt introduction of CCR5 antagonists in clinical practice. Bioinformatics tools based on V3 sequences might help to predict HIV-1 tropism; however, most of these methods have been designed by taking only genetic information derived from HIV-1 subtype B into consideration. The aim of this study was to evaluate the performances of several genotypic tools to predict HIV-1 tropism in non-B subtypes, as data on this issue are scarce. Plasma samples were tested using a new phenotypic tropism assay (Phenoscript-tropism; Eurofins), and results were compared with estimates of coreceptor usage using eight different genotypic predictor softwares (Support Vector Machine [SVM], C4.5, C4.5 with positions 8 to 12 only, PART, Charge Rule, geno2pheno coreceptor, Position-Specific Scoring Matrix X4R5 [PSSM(X4R5)], and PSSM(sinsi)). A total of 150 samples were tested, with 115 belonging to patients infected with non-B subtypes and 35 drawn from subtype B-infected patients, which were taken as controls. When non-B subtypes were tested, the concordances between the results obtained using the phenotypic assay and distinct genotypic tools were as follows: 78.8% for SVM, 77.5% for C4.5, 82.5% for C4.5 with positions 8 to 12 only, 82.5% for PART, 82.5% for Charge Rule, 82.5% for PSSM(X4R5), 83.8% for PSSM(sinsi), and 71.3% for geno2pheno. When clade B viruses were tested, the best concordances were seen for PSSM(X4R5) (91.4%), PSSM(sinsi) (88.6%), and geno2pheno (88.6%). The sensitivity for detecting X4 variants was lower for non-B than for B viruses, especially in the case of PSSM(sinsi) (38.4% versus 100%, respectively), SVM(wetcat) (46% versus 100%, respectively), and PART (30% versus 90%, respectively). In summary, while inferences of HIV-1 coreceptor usage using genotypic tools seem to be reliable for clade B viruses, their performances are poor for non-B subtypes, in which they particularly fail to detect X4 variants.

Virological fitness of HIV in patients with resistance to enfuvirtide.

Resistance to the HIV fusion inhibitor enfuvirtide is associated with mutations in the first heptad repeat region of gp41, but little is known of their impact on replicative fitness in vivo. We followed seven patients undergoing salvage therapy that included enfuvirtide in order to document the temporal generation of genotypic and phenotypic resistance in parallel with replicative fitness. Resistance to enfuvirtide was not associated with decreased replicative fitness of HIV strains infecting these patients.

Correlation between a phenotypic assay and three bioinformatic tools for determining HIV co-receptor use.

The predictive value of three genotypic methods to determine HIV-1 co-receptor usage was assessed in 83 plasma specimens taking as reference the results obtained using a recombinant phenotypic assay (Phenoscript). The best concordance was found for webPSSM, followed by geno2pheno and wetcat (85.9, 71.8 and 70.5%, respectively). Less than 5.1% of phenotypic X4 viruses were missed by genotypic tools. The genotypic prediction of HIV-1 co-receptor usage can thus assist therapeutic decisions for using CCR5 antagonists.

Susceptibility of human testis to human immunodeficiency virus-1 infection in situ and in vitro.

Semen represents the main vector for human immunodeficiency virus (HIV) dissemination worldwide and has been shown to harbor replication-competent virus despite otherwise effective highly active anti-retroviral therapy, which achieves undetectable viral load in plasma. Despite this, the origin of seminal HIV particles remains unclear, as does the question of whether the male genital tract organs contribute virus to semen. Here we investigated the presence of HIV receptors within the human testis using immunohistochemistry and quantitative real-time polymerase chain reaction. We also analyzed the infectivity of a dual tropic HIV-1 strain in an organotypic culture, as well as the impact of viral exposure on testosterone production. Our study establishes that CXCR4+, CCR5+, CD4+, and DC-SIGN+ cells are present within the interstitial tissue of human testis and that these molecules persist throughout our organotypic culture. Our data also reveal that the human testis is permissive to HIV-1 and supports productive infection, leaving testosterone production apparently unaffected. Infected cells appeared to be testicular macrophages located within the interstitial tissue. That the testis itself represents a potential source of virus in semen could play a role in preventing viral eradication from semen because this organ constitutes a pharmacological sanctuary for many current antiretrovirals.

Human Leydig cells are productively infected by some HIV-2 and SIV strains but not by HIV-1.

OBJECTIVES: With the use of highly active antiretroviral therapy, the identification of HIV reservoirs within the body has become an important issue. However, the testis has been largely ignored despite representing a pharmacologic sanctuary which could act as a viral reservoir. DESIGN: Because alterations in testosterone production have frequently been reported in HIV-infected individuals, we investigated whether the testosterone-producing Leydig cells could become directly infected by HIV-1, HIV-2 or SIV. METHODS: Purified Leydig cells were infected with a panel of HIV-1, HIV-2 and SIV strains and examined for expression of HIV/SIV receptors. Additionally, the impact of CD4 transduction on Leydig cell infection was determined. RESULTS: Leydig cells were unable to support productive infection of the seven HIV-1 isolates tested. No CD4, CXCR4 or CCR5 expression was evident on the surface of Leydig cells and transduction with a CD4 expressing adenovirus did not induce HIV-1 infection. In contrast, some primary and laboratory adapted CD4-independent HIV-2 and SIV strains were able to enter and replicate productively in Leydig cells. CONCLUSIONS: Our results suggest that Leydig cells do not represent a target for HIV-1 infection within the testis. In contrast, Leydig cells support HIV-2 and SIV infection and thus represent a potential target for infection. Receptor use and significance of HIV-2/SIV infection of Leydig cells remain to be determined.