Evaluation of the Abbott ARCHITECT HIV Ag/Ab combo assay for determining recent HIV-1 infection

BACKGROUND

Given the challenges and costs associated with implementing HIV-1 incidence assay testing, there is great interest in evaluating the use of commercial HIV diagnostic tests for determining recent HIV infection. A diagnostic test with the capability of providing reliable data for the determination of recent HIV infection without substantial modifications to the test protocol would have a significant impact on HIV surveillance. The Abbott ARCHITECT HIV Ag/Ab Combo Assay is an antigen/antibody immunoassay, which meets the criteria as the first screening test in the recommended HIV laboratory diagnostic algorithm for the United States.

METHODS

In this study, we evaluated the performance characteristics of the ARCHITECT HIV Ag/Ab Combo signal-to-cutoff ratio (S/Co) for determining recent infection, including estimation of the mean duration of recent infection (MDRI) and false recent rate (FRR), and selection of recency cutoffs.

RESULTS

The MDRI estimates for the S/Co recency cutoff of 400 is within the 4 to 12 months range recommended for HIV incidence assays, and the FRR rate for this cutoff was 1.5%. Additionally, ARCHITECT Combo S/Co values were compared relative to diagnostic test results from two prior prospective HIV-1 diagnostic studies in order to validate the use of the S/Co for both diagnostic and recency determination.

CONCLUSION

Dual-use of the ARCHITECT Combo assay data for diagnostic and incidence purposes would reduce the need for separate HIV incidence testing and allow for monitoring of recent infection for incidence estimation and other public health applications.

Utility of grey zone testing strategy in transfusion transmissible infection testing in blood bank is of limited value!

Several blood banks use grey zone (GZ) phenomenon (defined as samples with optical density within 10% below the cut off in enzyme immuno-assay [EIA]/chemiluminescence immunoassay [CLIA]) to further augment blood safety. There is paucity of data regarding usefulness of GZ sample and its application in Transfusion Transmissible Infection (TTI) screening procedures in blood transfusion services. We looked at our GZ sample results and their confirmatory test results to verify if it adds to blood safety in our set-up? We performed a prospective analytical study on blood donors' samples over two years. All the donors' samples were screened for TTI using CLIA. Samples with signal/cut-off ratio between ≥0.90 and <1.00 were classified under GZ. They were re-tested in duplicate and submitted to confirmatory testing: Neutralization Test for HBsAg, Immunoblot for HCV, and Western blot for HIV. Among the 50,064 blood donors donating the blood during study period, 573 (1.14%) donors were reactive for HBsAg, HCV, and HIV. Forty-seven (0.1%) TTI samples were GZ, but none was "confirmed positive." The utility of GZ testing seems to be limited. However, this may be continued for sake of "erring on the side of caution" and since this only results in negligible wastage (0.1%) of blood units.

Sample-to-cutoff ratios using Architect HIV Ag/Ab Combo: The influence with the results of supplemental tests and optimal cutoff value to predict HIV infection

BACKGROUND

The Architect HIV Ag/Ab Combo has excellent performance for HIV screening; however, the false-positive rate (FPR) was high in low HIV prevalence setting.

OBJECTIVES

The purpose of this study was to analyze the influence of sample-to-cutoff (s/co) ratios by Architect HIV Ag/Ab Combo with the results of confirmatory test and explore the potential utility of s/co to predict HIV infection.

METHODS

A retrospective review on Architect HIV Ag/Ab Combo reactive results was performed at a teaching hospital in Xi'an. The s/co values in different groups, that is, true positives (TP) and false positives (FP), different Western blotting (WB) bands among WB-positive cases, were compared. The receiver operating characteristic curve (ROC) analysis was used to determine the optimal cutoff value for predicting HIV infection.

RESULTS

During the study period, 219 out of 84 702 patients were reactive by ARCHITECT with a 0.0992% of HIV prevalence and a 56.25% of FPR. The mean s/co ratios in TP were significantly higher than that in FP (458.15 vs 3.11, P < 0.0001). Among the WB-positive cases, the s/co ratios increased significantly with the increase in the number of bands, P = 0.0065. The optimal cutoff (24.44) by ROC analysis can provide the highest sum of sensitivity (100%) and specificity (100%) with no FP results.

CONCLUSIONS

For Architect HIV Ag/Ab Combo, the FPR is reduced when s/co ratios increase, and the s/co ≥24.44 may be reliable to predict HIV infection.

Validation of the Limiting Antigen Avidity Assay to Estimate Level and Trends in HIV Incidence in an A/D Epidemic in Rakai, Uganda

The limiting-antigen avidity (LAg-Avidity) assay with viral load (VL) >1,000 copies/mL is being used to estimate population-level HIV incidence in Africa. However, this has not been validated in East Africa where HIV-1 subtypes A and D circulate. Sera from persons seen in two surveys (2008-2009 and 2012-2013) limited to those who attended the previous round of the Rakai Community Cohort in Uganda were analyzed. The performance of the current LAg-Avidity protocol, with a mean duration of recent infection (MDRI) of 130 days and false recent rate (FRR) of 0%, was compared with subtype-specific MDRI and FRR, adjusted to subtype distributions. The observed incidence was 1.05/100 person years (py) [95% confidence interval (CI) 0.90-1.23] in 2008-2009 and 0.66/100 py (95% CI 0.52-0.83) in 2012-2013. In contrast, the per-protocol LAg-Avidity incidence estimates were 1.63/100 py (95% CI 0.97-2.30) in 2008-2009 and 2.55/100 py (95% CI 1.51-3.59) in 2012-2013 (a significant increase, p < .05.) However, using a subtype-specific MDRI and FRR, the subtype adjusted incidence was 0.88% (95% CI 0.44-1.33) in 2008-2009 and 0.67% (95% CI 0.00-1.68) in 2012-2013, approximating to the observed incidence trends. In this subtype A/D epidemic, the per protocol LAg-Avidity + VL assay overestimated HIV incidence and failed to detect declines in incidence. Adjustment for FRR, MDRI, and subtype distribution provided incidence estimates similar to empirically observed incidence level and trends. Thus, use of the LAg-Avidity assay in an A/D epidemic requires adjustment for subtype.

Performance of the Alere Determine™ HIV-1/2 Ag/Ab Combo Rapid Test with algorithm-defined acute HIV-1 infection specimens

BACKGROUND

The capacity of HIV Antigen/Antibody (Ag/Ab) immunoassays (IA) to detect HIV-1 p24 antigen has resulted in improved detection of HIV-1 infections in comparison to Ab-only screening assays. Since its introduction in the US, studies have shown that the Determine HIV-1/2 Ag/Ab Combo assay (Determine Ag/Ab) detects HIV infection earlier than laboratory-based IgM/IgG-sensitive IAs, but its sensitivity for HIV-1 p24 Ag detection is reduced compared to laboratory-based Ag/Ab assays. However, further evaluation is needed to assess its capacity to detect acute HIV-1 infection.

OBJECTIVE

To assess the performance of Determine Ag/Ab in serum from acute HIV-1 infections.

STUDY DESIGN

Select serum specimens that screened reactive on a laboratory-based Ag/Ab IA or IgM/IgG Ab-only IA, with a negative or indeterminate supplemental antibody test and detectable HIV-1 RNA were retrospectively tested with Determine Ag/Ab. Results were compared with those of the primary screening immunoassay to evaluate concordance within this set of algorithm-defined acute infections.

RESULTS

Of 159 algorithm-defined acute HIV-1 specimens, Determine Ag/Ab was reactive for 105 resulting in 66.0% concordance. Of 125 that were initially detected by a laboratory-based Ag/Ab IA, 81 (64.8%) were reactive by Determine Ag/Ab. A total of 34 acute specimens were initially detected by a laboratory-based IgM/IgG Ab-only IA and 24 (70.6%) of those were reactive by Determine Ag/Ab.

CONCLUSIONS

Due to their enhanced sensitivity, laboratory-based Ag/Ab IAs continue to be preferred over the Determine Ag/Ab as the screening method used by laboratories conducting HIV diagnostic testing on serum and plasma specimens.

An analysis of the predictive value of the HIV Ag/Ab screening assay within the performance characteristics of the DiaSorin LIAISON XL for the detection of blood-borne viruses

BACKGROUND

Correct identification of blood borne viral infections, such as hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) is crucial in detection and follow up of infection in patients.

OBJECTIVES

We evaluated the diagnostic performance of the DiaSorin LIAISON XL (LIAISON XL) for screening of HBV, HCV and HIV infection. In addition, we investigated the variability of the signal-to-cuttoff ratio (S/CO) of the LIAISON XL HIV Ag/Ab assay and it's predictive value in subsequent confirmation of HIV-1 infection.

STUDY DESIGN

We analyzed 16,497 blood samples on which HBV, HCV and HIV screening was performed. We defined A) archived samples previously tested with an arbitrary result in the Abbott ARCHITECT i2000SR system; B) prospectively collected samples which were simultaneously tested on the LIAISON XL and ARCHITECT i2000SR; C) prospectively collected serum samples for HIV testing which were tested solely on the LIAISON XL.

RESULTS

The agreements of HBV-, HCV-, and HIV markers between the two compared systems are remarkably high. Among the samples which were prospectively tested for HIV Ab/Ag on the LIASON XL, 229 (1.6%) were reactive of which 141 (61.6%) could be confirmed. Increasing the signal-to-cutoff value to 4 could increase the positive predictive value (PPV) to 88.1% without decreasing sensitivity.

CONCLUSIONS

The LIAISON XL system proved to be an excellent system for diagnosing HBV, HCV, and HIV. Our data for the first time showed that increasing the HIV S/CO ratio was safe and increased the PPV for confirmed HIV infection in the tested population.

Comparative evaluation of three FDA-approved HIV Ag/Ab combination tests using a genetically diverse HIV panel and diagnostic specimens

BACKGROUND

HIV Ag/Ab combination assays are recommended by CDC for routine screening and several HIV Ag/Ab combination tests are now FDA-approved. Maintaining high specificity and consistent sensitivity across diverse HIV strains is critical for these assays to accurately detect HIV infection and expedite delivery of patient results.

OBJECTIVES

To evaluate performance of three FDA-approved HIV tests: ARCHITECT HIV Combo (Abbott), ADVIA Centaur HIV Combo (Siemens) and BioPlex HIV Ag-Ab (Bio-Rad).

STUDY DESIGN

Sensitivity and specificity were evaluated using an extensive panel of 28 HIV infected human specimens and 17 cultured virus isolates representing multiple genotypes, 6 seroconversion panels, 4 human samples with acute infection, WHO p24 standard and 4020 clinical specimens.

RESULTS

The p24 limit of detection (LOD) for the WHO standard was 0.19IU/ml, 0.70IU/ml, and 1.77IU/ml in BioPlex, ARCHITECT, and Centaur respectively. The distribution of LODs across 15 HIV-1 isolates was substantially narrower in ARCHITECT (5-33pg/ml) than in BioPlex (11-198pg/ml) and Centaur (6-384pg/ml). All assays detected antibodies to the majority of HIV-1 and HIV-2 variants. However, reduced sensitivity was observed for Centaur in detection of antibodies to HIV-1 group M (CRF02_AG), O and N variants. BioPlex and ARCHITECT showed better seroconversion sensitivity than Centaur, detecting one bleed (3-7 days) earlier in 4 (BioPlex) and 3 (ARCHITECT) of 6 seroconversion panels. ARCHITECT demonstrated the highest specificity (99.90-100%) compared to BioPlex (99.80%) and Centaur (99.42%).

CONCLUSIONS

The overall performance of ARCHITECT and BioPlex was superior to Centaur, especially for detection of acute HIV infection.

Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting

BACKGROUND

Despite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results.

OBJECTIVES

The influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated.

STUDY DESIGN

A total of 30,201 sera were tested for HIV diagnosis using Abbott Architect^® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO≥1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed.

RESULTS

Among the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO≥1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO≥1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO>50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found.

CONCLUSIONS

We show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases.

In-depth analysis of compartmentalization of HIV-1 matrix protein p17 in PBMC and plasma

HIV-1 p17 plays an important role in the virus life-cycle and disease pathogenesis. Recent studies indicated a high heterogeneity of p17. A high number of insertions in the p17 carboxy-terminal region have been more frequently detected in patients with non-Hodgkin lymphoma (NHL), suggesting a role of altered p17 in lymphomagenesis. Based on p17 heterogeneity, possible PBMC/plasma compartmentalization of p17 variants was explored by ultra-deep pyrosequencing in five NHL patients. The high variability of p17 with insertions at the carboxy-terminal region was confirmed in plasma and observed for the first time in proviral genomes. Quasispecies compartmentalization was evident in 4/5 patients. Further studies are needed to define the possible role of p17 quasispecies compartmentalization in lymphomagenesis.

Hepatitis B, Hepatitis C, and Human Immune deficiency Virus Seroconversion Positivity Rates and Their Potential Risk Factors Among Patients on Maintenance Hemodialysis in Cameroon

INTRODUCTION

Maintenance hemodialysis is a high-risk environment for transmission of blood-borne viruses. We aimed to assess the seroconversion rates of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immune deficiency virus (HIV) infections in patients on maintenance hemodialysis in a tertiary care hospital in Cameroon.

MATERIALS AND METHODS

Patients with serology records at initiation of hemodialysis, and a minimum duration on hemodialysis of 4 months were included. Baseline demographic and clinical data were recorded. Patients were tested with a third and fourth generation immune-enzymatic assay for hepatitis B surface antigen and anti-HCV antibodies, respectively. For HIV, a rapid Ag/Ab combo test and an ImmunoComb II HIV (for confirmation) were used.

RESULTS

Ninety-seven patients, 66% men, mean age of 51 ± 14 years and mean duration on hemodialysis of 32.8 ± 27.5 months, were included. Seroprevalence at dialysis initiation was 6.2%, 20.6%, and 9.3%, respectively, for HBV, HCV, and HIV. Ninety patients (92.8%) received blood transfusions while on hemodialysis. Seroconversion rates were 1.1% for hepatitis B surface antigen, 11.8%, for anti-HCV antibodies, and 0.0% for HIV. Longer duration on dialysis was associated with HCV seroconversion (62.7 months versus 29.2 months, P < .001).

CONCLUSIONS

Seroconversion rate in hemodialysis was high for HCV, low for HBV, and nil for HIV. Longer duration on dialysis was associated with HCV seroconversion. Our study suggests an urgent need to lay emphasis on universal precaution measures in order to reduce the risk of hepatitis seroconversion in the unit.

Opt-Out Panel Testing for HIV, Hepatitis B and Hepatitis C in an Urban Emergency Department: A Pilot Study

OBJECTIVES

Studies suggest 2 per 1000 people in Dublin are living with HIV, the level above which universal screening is advised. We aimed to assess the feasibility and acceptability of a universal opt-out HIV, Hepatitis B and Hepatitis C testing programme for Emergency Department patients and to describe the incidence and prevalence of blood-borne viruses in this population.

METHODS

An opt-out ED blood borne virus screening programme was piloted from March 2014 to January 2015. Patients undergoing blood sampling during routine clinical care were offered HIV 1&2 antibody/antigen assay, HBV surface antigen and HCV antibody tests. Linkage to care where necessary was co-ordinated by the study team. New diagnosis and prevalence rates were defined as the new cases per 1000 tested and number of positive tests per 1000 tested respectively.

RESULTS

Over 45 weeks of testing, of 10,000 patient visits, 8,839 individual patient samples were available for analysis following removal of duplicates. A sustained target uptake of >50% was obtained after week 3. 97(1.09%), 44(0.49%) and 447(5.05%) HIV, Hepatitis B and Hepatitis C tests were positive respectively. Of these, 7(0.08%), 20(0.22%) and 58(0.66%) were new diagnoses of HIV, Hepatitis B and Hepatitis C respectively. The new diagnosis rate for HIV, Hepatitis B and Hepatitis C was 0.8, 2.26 and 6.5 per 1000 and study prevalence for HIV, Hepatitis B and Hepatitis C was 11.0, 5.0 and 50.5 per 1000 respectively.

CONCLUSIONS

Opt-out blood borne viral screening was feasible and acceptable in an inner-city ED. Blood borne viral infections were prevalent in this population and newly diagnosed cases were diagnosed and linked to care. These results suggest widespread blood borne viral testing in differing clinical locations with differing population demographic risks may be warranted.

Monitoring the patient response as an alternative to commercial negative quality control in infectious serology

BACKGROUND

Traditional internal quality control schemes for qualitative infectious serology mostly rely on the use of commercial positive and negative quality control materials. However, with respect to the negative control, target values provided by the manufacturer are often poorly defined and non-commutability of the commercial materials further complicates correct interpretation of control results. An alternative quality control procedure using the median patient seronegative response is presented.

STUDY DESIGN

Daily patient median responses were calculated for our Hepatitis B surface antigen, Hepatitis B core antibody, Hepatitis C antibody and HIV antigen/antibody test systems. Because of the low prevalence of these viruses in our area, most patient responses are negative. A minimum of 5 patient samples per day was required to generate a stable daily median. Control limits were calculated and daily patient medians were plotted against commercial quality control results.

RESULTS

Commercial negative controls and daily patient medians mostly behaved in the same way. Nevertheless, for the Hepatitis B surface antigen test, patient medians frequently exceeded the calculated control limit in contrast to commercial quality controls. This confirms that target ranges provided by the manufacturer are not always adequate. Moreover, an important matrix-related interference occurred on our HIV antigen/antibody test system and correct interpretation was only possible using daily patient median results.

CONCLUSION

Monitoring the daily patient median response can be a valuable alternative to traditional commercial negative quality control. It's easy to perform, cost-free, provides additional information with respect to matrix effects and allows for the establishment of well-defined control limits.

Machine learning methods enable predictive modeling of antibody feature:function relationships in RV144 vaccinees

The adaptive immune response to vaccination or infection can lead to the production of specific antibodies to neutralize the pathogen or recruit innate immune effector cells for help. The non-neutralizing role of antibodies in stimulating effector cell responses may have been a key mechanism of the protection observed in the RV144 HIV vaccine trial. In an extensive investigation of a rich set of data collected from RV144 vaccine recipients, we here employ machine learning methods to identify and model associations between antibody features (IgG subclass and antigen specificity) and effector function activities (antibody dependent cellular phagocytosis, cellular cytotoxicity, and cytokine release). We demonstrate via cross-validation that classification and regression approaches can effectively use the antibody features to robustly predict qualitative and quantitative functional outcomes. This integration of antibody feature and function data within a machine learning framework provides a new, objective approach to discovering and assessing multivariate immune correlates.

Evaluation of HIV antigen/antibody combination ELISAs for diagnosis of HIV infection in Dar Es Salaam, Tanzania

INTRODUCTION

The aim of this study was to evaluate the performance of Enzygnost HIV Integral II antigen/antibody combination ELISAs in order to formulate HIV ELISA testing algorithms for the Ministry of Health and Social Welfare, Tanzania.

METHODS

This was a laboratory-based evaluation of Enzygnost HIV Integral II Antibody/ Antigen, Murex HIV antigen/antibody and Vironostika HIV Uniform II antigen/antibody conducted between October 2011 and May 2012.

RESULTS

A total of 600 blood samples were included in the evaluation. A total of 209/596 (35.1%) serum samples were confirmed HIV positive. Of these, the prevalence of HIV infection was 2.3% (3/130), 2.3% (3/127), 2.2% (3/139) and 100% (200/200) for VCT clients, ANC attendees, blood donors and CTC patients, respectively. Three hundred and eighty seven (64.9%) were HIV negative samples. Sensitivity was 100% (95% CI; 98.3-100%) for all the three HIV ELISAs. The specificity for the Enzygnost HIV Integral II and Murex was 100% (95% CI; 99.1-100%). The final specificity at repeat testing was 99.5% (95% CI; 98.2-99.9%) for Vironostika. Enzygnost HIV Integral II detected HIV infection seven days since first bleed.

CONCLUSION

Initial testing using either Vironostika or Murex HIV antigen/antibody combination ELISA followed by testing of reactive samples on the Enzygnost HIV Integral II gave a sensitivity and specificity of 100% with reduced window period. Combination of two HIV antigen/antibody combination ELISAs can be used as an alternative confirmatory testing strategy for screening of donated blood at the National and Zonal blood transfusion centres and in lab diagnosis of HIV infection.

Performance of Alere Determine HIV-1/2 Ag/Ab Combo rapid test for acute HIV infection: a case report

We describe a case of symptomatic acute HIV infection in a young man where a fourth-generation rapid screening test combining HIV-specific antibody and p24 antigen was negative. In highly suspicious cases of acute HIV infection, plasma HIV RNA assays together with conventional, non-rapid screening tests should be used.

Concerns of occupational HIV infection among surgical Staff in the light of anti-HIV sero-status and the distribution of Δ32 allele of the CCR5 gene: a cross-sectional study

Surgical staff might be considered at most risk of accidental viral infection due to their higher exposure to blood.

AIM

To evaluate surgical staff concerns about occupational HIV infection, to determine contributing factors, to assess their sero-status regarding this pathogen, and the frequency of the Δ32 allele of the CCR5 gene.

METHODS

With the use of a self-administered anonymous questionnaire a cross-sectional sero-survey was conducted from February 2009-January 2010 among doctors/nurses from the surgical/ gynaecological wards of 16 randomly selected hospitals in Western Pomerania, Poland. Fear level was measured by the use of the VAS scale (range 0-10). Serum samples were tested by ELISA. Genotyping was performed using a PCR-AFLP assay.

RESULTS

Response rate 84.9%; 427 participants, 88.3% females; 84.8% nurses, 15.2% doctors (median age 42 years, range 22-61 years). More than two thirds of respondents (67.2%) overestimated HIV single exposure risk. The median level of occupational HIV fear was 6.67. The prevalence of anti-HIV was 0.0% (95%CI: 0-0.9%); 1.2% (95%CI: 0.5%-2.9%) of participants were homozygotes Δ32/Δ32. The stepwise regression model revealed that job category (nurse) was associated with HIV fear (p<0.001).

CONCLUSIONS

The risk of contracting occupational HIV infection remains low; no anti-HIV positive individuals were found among surgical staff, one in one hundred were resistant to HIV infection. Staff members, especially nurses, were much concerned with acquiring an occupational HIV infection, possibly due to the lack of knowledge on single exposure risk. Educational actions and better access to specialists which would help surgical staff in managing anxiety at the workplace is urgently needed.

Discrepant HIV results resolved by human DNA testing

A high-risk patient was informed of a positive HIV antibody/antigen test. However, follow-up samples taken 2-3 months later for HIV RNA and anti-HIV antibodies were negative. Human DNA testing confirmed that all samples were from this patient, excluding a sample mix-up. Laboratory investigations revealed a likely splash-over contamination event.

Evaluation of human immunodeficiency virus-1/2 antigen/antibody immunochromatographic assay

BACKGROUND

In Japan, an immunochromatographic HIV-1/2 assay has been used for local Health Care Centers to prevent HIV spread in early stages and for hospitals at night or on holidays, where automated instruments are not available. In 2009, a new immunochromatographic HIV-1/2 assay became available which detects both antigen (Ag) and antibody (Ab) simultaneously and on separate bars. This study was conducted to evaluate the clinical performance of this new assay against three HIV-1/2 assays.

METHODS

One immunochromatographic assay (ICA) for HIV Ab detection, one chemiluminescent enzyme immunoassay (CLEIA) for Ab detection and one ELISA for Ag/Ab combination assay were evaluated with the ICA for Ag/Ab detection. Serum samples from 955 patients were used at Osaka University Hospital, who had been tested initially for HIV infection status. The 900 were negative and 55 were positive. In addition, the samples in 10 commercially available panels [2 containing relatively rare HIV subtypes/genotypes and 8 containing seroconversion samples] were tested using all HIV assays.

RESULTS

The HIV Ag/Ab ICA showed 100% (900/900, 95% confidence interval (95 CI) 99.59 - 100%) clinical specificity and was better than 99.8% (898/900, 95 CI 99.20 - 99.97%) of the existing ICA. The CLEIA and ELISA showed 100% (600/600, 95 CI 99.39 - 100%) and 99.8% (598/600, 95 CI 98.80 - 99.96%) specificity, respectively. The HIV Ag/Ab ICA showed 100% (55/55, 95 CI 93.51 - 100%) clinical sensitivity and detected all the relatively rare HIV subtypes/genotype panels; these results were the same as the other three assays. The HIV Ag/Ab ICA detected 5 seroconversion panels earlier than antibody-only-detection assays but detected later with 2 panels than ELISA for Ag/Ab combination assay.

CONCLUSIONS

The HIV Ag/Ab ICA demonstrated good performances in clinical specificity and sensitivity as a rapid assay and is a suitable assay for qualitative judgement of HIV Ag and Ab simultaneously in human serum and plasma.

Evaluation of the dried blood spot (DBS) collection method as a tool for detection of HIV Ag/Ab, HBsAg, anti-HBs and anti-HCV in a Malaysian tertiary referral hospital

INTRODUCTION

Dried blood spot (DBS) collection is an appealing alternative to whole blood or plasma sampling, as it has technical and economic advantages over the latter.

MATERIALS AND METHODS

A prospective cross-sectional study was conducted at a Malaysian tertiary referral hospital from November 2009 to March 2010. One hundred and fifty paired specimens of DBS and plasma were analysed by the standard assays for HIV Ag/Ab, HBsAg, anti-HBS and anti-HCV, separately (total 600 paired specimens). DBS sample titres were then compared to the results of plasma testing, which was used as the gold standard.

RESULTS

For the HIV Ag/Ab assay with a cut-off point of 0.35 Relative Light Units (RLUs), the sensitivity and specificity were both 100%. For the HBsAg assay, the sensitivity was 96.5% and the specificity was 97.8%, with a cut-off point of 1.72 RLUs. Sensitivity for the anti-HBs test was 74.2% and the specificity was 86.9%, using a cut-off point of 0.635 RLUs. For the anti-HCV assay, the sensitivity was 97.3% and the specificity was 100%, with a cut-off point of 0.10 RLUs.

CONCLUSION

DBS is an ideal choice to be used as a screening tool for the detection of HIV, Hepatitis B and Hepatitis C virus infections. However, different cut-off values need to be used for the validation of test positivity in DBS samples because the small amount of blood in the DBS specimens leads to lower assay titres.

Infectious disease screening of blood specimens collected post-mortem provides comparable results to pre-mortem specimens

Serology assays for standard screening are optimised for use with sera collected from living adults and children. Because of potential changes in the vascular compartments after death, methods used for screening sera from cadaveric organ donors need to be validated before testing these specimens. Serum was separated from blood collected from cadaveric donors within 24 h of death and biochemical parameters measured to detect dilution of protein and haemolysis. In order to demonstrate if any inhibitors that might interfere with the assays were present, pre and post-mortem specimens were spiked with aliquots of human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), human T-cell Lymphotropic Virus (HTLV) and T. pallidum-positive sera. Comparison of serum from living subjects with serum obtained post-mortem showed that while the concentration of total protein decreased, concentrations of albumin, immunoglobulin G (IgG) and immunoglobulin M (IgM) remained unchanged. The degree of haemolysis, as measured by free haemoglobin, was within the limits accepted for the Architect analyser. Spiking of pre- and post-mortem specimens with aliquots of HIV, HCV, HBV, HTLV and T. pallidum-positive sera showed no statistical difference in the signal between pre-mortem and post-mortem results when tested on the Abbott Architect analyser. Positive results were obtained in each of a further nine subjects who had tested positive for HIV (n=1), HCV (n=8), HBV (n=1) on pre-mortem serological testing. These findings suggest that the sensitivity of the Abbott Architect serological screening tests is not significantly affected in specimens collected within 24 h of the cessation of life.

Census and analysis of persistent false-negative results in serological diagnosis of human immunodeficiency virus type 1 group O infections

Human immunodeficiency viruses (HIV) have a high level of genetic diversity. The outlier variants of HIV type 1 (HIV-1) group O are distantly related to HIV-1 group M. Their divergence has an impact on serological diagnosis, with a risk of false-negative results. In this study, we report 20 failure cases, involving patients with primary or chronic infection, in France and Cameroon between 2001 and 2008. Our results indicate that some assays detected group O infection much less efficiently than others. Two major reasons for these false-negative results were identified: the presence or absence of a group O-specific antigen (and the designed sequence) for the detection of antibodies and the greater envelope variability of group O than of group M strains. This study highlights the complexity of screening for these divergent variants and the need to evaluate test performance with a large panel of strains, due to the extensive diversity of group O variants.

Ultrasensitive quantitative HIV-1 p24 antigen assay adapted to dried plasma spots to improve treatment monitoring in low-resource settings

BACKGROUND

Our group has previously developed a quantitative and ultrasensitive HIV-1 p24 antigen assay that is inexpensive, easy-to-perform, and can be carried out in low-resource settings. Since antiretroviral therapies are becoming more accessible in resource-constrained countries, methods to assess HIV-1 viraemia are urgently needed to achieve a high standard of care in HIV-1 management.

OBJECTIVES

To adapt our quantitative assay to dried plasma spots (DPS), in order to further simplify this test and make it more accessible to resource-constrained countries.

STUDY DESIGN

DPS from 47 HIV-seropositive, treated or untreated adult individuals and 30 healthy individuals were examined.

RESULTS

A specificity of 100% was observed when p24 antigen was measured using DPS, and no differences of p24 concentration could be seen between DPS and venous plasma. The correlation between DPS and venous plasma p24 was excellent (R=0.93, CI(95%)=0.88-0.96, p<0.0001). Similarly, p24 antigen concentrations using DPS were well correlated with RNA viral load (R=0.53, CI(95%)=0.27-0.72, p=0.0002).

CONCLUSIONS

This quantitative p24 antigen test has similar sensitivity and specificity using DPS and venous plasma, and has the potential to improve health care delivery to HIV-affected individuals in resource-constrained countries.

Alternative approach to blood screening using the ExaVir reverse transcriptase activity assay

408 non-selected samples were obtained from healthy, adult individuals donating blood at the Ethiopian Red Cross Society-National Blood Transfusion Service. All samples were screened for HIV using the Vironostika Ag/Ab test, the Amplicor DNA PCR and examined for the presence of HIV reverse transcriptase (RT) using the ExaVir Load test (version 2). A panel of supplementary tests was used to evaluate the HIV status of the discordant samples and to confirm positivity. One aim was to assess an RT based test for screening for HIV in comparison with other more conventional tests. An HIV-prevalence of 3.4 % (14/408) was found. The Vironostika Ag/Ab test produced 391 negative, and according to the supplementary testing, 14 true- and three false- positive test results. The corresponding figures for the Amplicor DNA PCR test was 384 negative, 14 true- and two extra probably false -positive samples. In addition, the DNA PCR generated eight indeterminate results. The colorimetric version of the ExaVir load test exhibited 100 % specificity and detected RT in 13 of the true positive samples, but failed to detect one sample containing 200 HIV RNA copies /mL. This sample was detectable in the fluorimetric version of the test. The detection of RT activity in addition to the currently used markers would seem to have a potential for use in blood screening.

Western blot profile in HIV infection

BACKGROUND

Although the overall sensitivity and specificity of the western blot (WB) test for detection of antibodies to various viral proteins is high, there has been a substantial difference in the timing of the appearance of antibody bands and their intensities during different stages of HIV infection.

AIMS

Mapping different band patterns of Western blot results and correlating them with stages of HIV infection.

METHODS

We performed a retrospective study with 1,467 HIV-1 infected cases confirmed by WB test between January 2002 to July 2005, with the objective of mapping different band patterns of western blot results and determining whether the presence or absence of certain bands was associated with any specific stage of HIV infection. For the interpretation of the WB results in this study, the guidelines recommended by NACO, India were followed.

RESULTS

Reactivity with all the bands was the most commonly observed WB pattern, occurring in 92.91% (1363/1467) of cases, whereas the other 7.09% showed uncommon band patterns. Of all individual bands, p31 band was the most frequently missing one, absent in 7.09% cases. On classifying the WB reactive cases by the WHO clinical staging system, 38.45% (564/1467) were in Stage 1, 47.99% (704/1467) in stages 2 and 3 and 13.56% in stage 4. Correlation of CD4 cell counts with the various uncommon band patterns showed that only 5.56% (4/72) had counts in the 200-500 cells/microl range, whereas 45.83% and 48.61% had counts of < 200 and> 500 cells/microl respectively.

CONCLUSION

Interpretation of the WB band pattern in combination with clinical features may be occasionally useful in predicting the stage of HIV infection.

[The use of dried blood spots for HIV-antibody testing in Sahel]

Undertaking a HIV seroepidemiological survey in Sahel is logistically problematic, since countries like Niger or Mali are very large with scattered populations and harsh climatic conditions. Therefore, the replacement of serum samples by whole blood dried on filter papers has been studied for HIV-antibody testing with commercial kits that are commonly used. In Niger, two tests ELISA (Genscreen HIV1/2 version 2, Vironostika HIV Uni-Form II Ag/Ab) and two rapid tests (Determine HIV1/2 et Immunocomb II HIV1&2 Bispot) were used to compare the dried blood spots and serum samples from 43 control individuals. Both ELISAs gave an excellent correlation (r = 0.99 et r = 0.98) between the dried blood spots and serum absorbance values. Using the rapid tests, the HIV status was found 100% concordant with dried blood spots and serum samples. An algorithm using three out of the four mentioned tests was defined then validated on the dried blood spots of 163 control individuals (100% concordant). In conclusion, dried blood spots may accurately and profitably replace serum samples for the serodiagnosis of HIV infection and for mass serosurveys in Sahel.

Comparative evaluation of TRI-DOT Rapid HIV test with fourth-generation ELISA for the detection of human immunodeficiency virus

This study evaluated the TRI-DOT Rapid HIV test for the early detection of human immunodeficiency virus (HIV) infection in comparison with a fourth-generation ELISA (Vironostika HIV Uniform II). Of 23,609 sera, seven (0.03%) gave discordant results. Six of these were reactive only by the fourth-generation assay and were p24 antigen-positive by VIDAS DUO, Western blot and qualitative RT-PCR tests. The remaining discordant serum was considered to be false-positive by the TRI-DOT assay, as it was negative by repeat ELISA and Western blot tests. The sensitivity and specificity of the TRI-DOT test were 99.48% and 99.99%, respectively, compared with the fourth-generation ELISA.

Performance evaluation of three automated human immunodeficiency virus antigen-antibody combination immunoassays

Three fourth-generation antigen/antibody combination assays (Elecsys, AxSYM, Architect HIV) and two third-generation (AxSYM, Centaur) HIV antibody immunoassays were evaluated. The evaluation panel of 479 samples included: nine tissue culture derived HIV-1 strains at four different p24 antigen concentrations (n=36), a p24 antigen sensitivity panel (n=10), 149 HIV-1 or HIV-2 confirmed antibody positive samples, ten anti-HIV-1 positive low titer samples, three seroconversion panels (n=21), and 253 HIV negative samples. The Architect had the best sensitivity for detection of HIV-1 antigen across eight HIV-1 subtypes, followed by the AxSYM while the Elecsys could not detect the highest antigen concentration evaluated (25 pg/mL) for eight of nine virus isolates. All assays showed 100% sensitivity for detection of HIV-1, group M, group O, and HIV-2 antibody positive samples. The Architect Ag/Ab Combo assay detected the first positive bleed of the three seroconversion panels and detected infection 4-26 days earlier than the third generation assays. Based on evaluation of 253 negative samples, assay specificity varied from 98.0% to 99.6%. The Architect HIV Ag/Ab Combo exhibited the best performance for specificity and detection of p24 antigen leading to closure of seroconversion window and demonstrating its utility for early diagnosis of HIV infection.

Comparative evaluation of the VIDAS HIV DUO Ultra assay for combined detection of HIV-1 antigen and antibodies to HIV

The aim of the study was to evaluate the performance of the combined antigen and antibody HIV screening assay VIDAS HIV DUO Ultra (BioMérieux, Marcy l'Etoile, France) in comparison with two other combined tests: the former version of the same test (VIDAS HIV DUO, BioMérieux) and the AxSYM HIV Ag/Ab Combo assay (Abbott Laboratories, Rungis, France). A prospective study was performed on serum specimens received on a routine basis for HIV testing: 1443 blood samples were tested with the three assays. Sensitivity was 100% for the three tests. Specificity assessed on repeated false-positive samples was 99.86, 99.03 and 99.65% for VIDAS HIV DUO Ultra, VIDAS HIV DUO and AxSYM HIV Ag/Ab Combo, respectively. In addition, 14 seroconversion panels were tested with the VIDAS DUO Ultra and AxSYM HIV Ag/Ab Combo assays. For four of these panels, a positive signal was detected one blood sampling point earlier with the VIDAS DUO Ultra assay, corresponding to a higher sensitivity of the HIV antigen test. These results indicate that the VIDAS HIV DUO Ultra exhibits an improved specificity with comparison to the former version of this assay and an excellent sensitivity for early detection of HIV seroconversion.

Challenges in the Testing of Non-Heart-Beating Cadavers for Viral Markers: Implications for the Safety of Tissue Donors

Natural changes that occur in blood and tissue after death may result in false positive results in antigen and antibody detection tests performed to identify markers of viral infection in potential tissue donors. Such tissue, which might otherwise be acceptable for therapeutic purposes, would not meet current standards for safe tissue banking. This is especially important in the context of insufficiency in the tissue supply. In this study, a series of blood samples collected during routine post-mortem examination was assayed using a range of commercially available kits for the detection of HBsAg, anti-HCV and anti-HIV 1 + 2 antibody/antigen. Results of tests on 104 samples collected from 97 individuals indicate that some kits result in a higher number of initial reactive samples than others. Approximately 40% of samples were reactive in one or more HBsAg assay, less than 10% in at least one anti-HIV kit and only 1 sample at low level on an anti-HCV kit. Liver or lymph node samples from individuals whose serum sample gave reactive results in antigen/antibody assays were tested for viral nucleic acid in the corresponding nucleic acid amplification test. Only one individual's sample was confirmed to test positive for HBsAg in a confirmatory neutralisation test and by nucleic acid amplification technology, and a second individual whose serum was scored reactive for anti-HCV, but negative for HBsAg, had a liver sample which was HBV DNA positive and HCV RNA negative. The results of the study indicate that antibody/antigen assays are not as specific as NAT using state of the art DNA extraction techniques. Both types of assay complement each other and used together will help assure the safety of tissues for transplantation.

Breast Milk-Derived Antigen-Specific CD8+ T Cells: An Extralymphoid Effector Memory Cell Population in Humans

Although mouse studies have demonstrated the presence of an effector memory population in nonlymphoid tissues, the phenotype of human CD8(+) T cells present in such compartments has not been characterized. Because of the relatively large number of CD8(+) T cells present in breast milk, we were able to characterize the phenotype of this cell population in HIV-infected and uninfected lactating women. CMV, influenza virus, EBV, and HIV-specific CD8(+) T cells as measured by the IFN-gamma ELISPOT and MHC class I tetramer staining were all present at greater frequencies in breast milk as compared with blood. Furthermore, a greater percentage of the breast milk CD8(+) T cells expressed the intestinal homing receptor, CD103, and the mucosal homing receptor CCR9. Breast milk T cells were predominantly CD45RO(+)HLADR(+) and expressed low levels of CD45RA, CD62L, and CCR7 consistent with an effector memory population. Conversely, T cells derived from blood were mainly characterized as central memory cells (CCR7(+)CD62L(+)). These results demonstrate a population of extralymphoid CD8(+) T cells with an effector memory phenotype in humans, which could contribute to enhanced local virologic control and the relative lack of HIV transmission via this route.

Complement Mediates the Binding of HIV to Erythrocytes

A fraction of HIV is associated with erythrocytes even when the virus becomes undetectable in plasma under antiretroviral therapy. The aim of the present work was to further characterize this association in vitro. We developed an in vitro model to study the factors involved in the adherence of HIV-1 to erythrocytes. Radiolabeled HIV-1 (HIV) and preformed HIV-1/anti-HIV immune complexes (HIV-IC) were opsonized in various human sera, purified using sucrose density gradient ultracentrifugation, and incubated with human erythrocytes. We observed that, when opsonized in normal human serum, not only HIV-IC, but also HIV, bound to erythrocytes, although the adherence of HIV was lower than that of HIV-IC. The adherence was abolished when the complement system was blocked, but was maintained in hypogammaglobulinemic sera. Complement-deficient sera indicated that both pathways of complement were important for optimal adherence. No adherence was seen in C1q-deficient serum, and the adherence of HIV was reduced when the alternative pathway was blocked using anti-factor D Abs. The adherence could be inhibited by an mAb against complement receptor 1. At supraphysiological concentrations, purified C1q mediated the binding of a small fraction of HIV and HIV-IC to erythrocytes. In conclusion, HIV-IC bound to erythrocytes as other types of IC do when exposed to complement. Of particular interest was that HIV alone bound also to erythrocytes in a complement/complement receptor 1-dependent manner. Thus, erythrocytes may not only deliver HIV-IC to organs susceptible to infection, but free HIV as well. This may play a crucial role in the progression of the primary infection.

Relevance of a combined HIV antigen/antibody assay to detect early HIV infections in a low prevalence population: case reports

The AxSYM HIV Ag/Ab Combo assay (Abbott) has proven to possess excellent sensitivity on seroconversion samples. Since its introduction in Sweden and Norway approximately one year ago, eight cases of acute HIV infections were found earlier compared to assays detecting only antibodies either to screen or to confirm an HIV infection. Data of the presented cases indicate that the early detection of primary HIV infection is of benefit to the individual patient and may reduce further spread of the disease. The impact of HIV combo assays on screening and diagnosis in a low prevalence population is discussed.

Potential of laser immunoassay for detection of HIV in human blood serum and urine

The potential of Light Scattering Immunoassay (LIA) for detection of HIV in human blood serum has been explored by monitoring the agglutination of antigen coated polystyrene particles by dynamic light scattering. ELISA tested human sera having HIV, TB, Filaria along with normal sera have been analyzed using two specific synthetic peptide antigen (SP1, SP2) and one nonspecific peptide antigen (NSP). Few paired human sera and urine samples and nonspecific (of nonHIV diseases) urine samples have also been tested using the same antigens to check the possibility of replacement of sera by urine.

Reduction of the diagnostic window in three cases of human immunodeficiency-1 subtype E primary infection with fourth-generation HIV screening assays

BACKGROUND AND OBJECTIVES

The influence of genetic variability on the sensitivity of serological diagnosis of human immunodeficiency virus (HIV) infection has, to date, been poorly investigated. The aim of the present study was to assess whether fourth-generation assays for the combined detection of HIV antigen and antibodies to HIV (anti-HIV) permit a reduction of the diagnostic window in comparison to third-generation antibody enzyme immunoassays (EIAs), which so far have shown a poor sensitivity for detection of HIV-1 non-subtype B primary infections.

MATERIALS AND METHODS

Three patients with primary HIV-1 subtype E (CRF01-AE) infection were tested with different third- and fourth-generation assays, stand-alone HIV antigen (Ag) EIAs and reverse transcription-polymerase chain reaction (RT-PCR). Additionally, virus lysates from HIV-1 Group M and O and HIV-2, at concentrations of p24 Ag close to the detection limit of licensed HIV Ag EIAs, were investigated with fourth-generation EIAs and HIV Ag EIAs.

RESULTS

In the first blood donor, the most sensitive fourth-generation assay detected HIV-1 infection 11 days earlier than five of the eight third-generation antibody assays. Fourth-generation EIAs, with a high sensitivity for HIV antigen, detected HIV-1 subtype E infection simultaneously or 4 days later than HIV-1 RT-PCR on pooled samples. Low concentrations of virus lysates of different HIV-1 subtypes A-H and group O, tested positive with fourth-generation EIAs, with a high sensitivity of the antigen-detection module.

CONCLUSIONS

Fourth-generation EIAs, especially those with a high sensitivity for HIV-1 p24 antigen, reduce the diagnostic window for primary HIV-1 subtype E infection in comparison with third-generation antibody-screening assays. These preliminary data from seroconversions and virus lysates indicate that the genetic diversity of HIV-1 does not represent a major challenge for the most sensitive EIAs of this new assay generation.

[Patients with HBV, HCV and HIV antigens--medical management, surgical procedures, equipment sterilization principles]

The purpose of the study was to present information about clinical treatment of HIV, HBV and HCV infection seropositive patients. We present indications and principles for hospitalization, conventional and surgical treatment and sterilization methods.

Human immunodeficiency virus type 1 Western blot: revised diagnostic criteria with fewer indeterminate results for epidemiological studies in Africa

BACKGROUND

Western blot (WB) criteria in epidemiological studies in Africa exhibit an unacceptably high proportion of indeterminate results. New diagnostic criteria are urgently needed.

METHODS

From 1989 to 1998, WB confirmatory tests were performed after weakly positive or discordant results of two enzyme immunoassays in a large Ugandan population. Enzyme immunoassays (EIA) on new sera taken prospectively from the same individuals one year later were used to assess the human immunodeficiency virus (HIV) status of these people. A logistic model was used to determine which set of WB bands was the most predictive of HIV status. Diagnostic criteria were then established, based on the likely HIV status determined using the predictive values and the intensity of the bands.

RESULTS

Using 1109 WB tests, the best diagnostic criteria were based on only two bands (gp160 and p31). These criteria were validated on an independent sample of 587 WB tests, giving a high sensitivity and specificity (90.3% and 97.0%, respectively) and few indeterminate results (2.7%). These criteria classified correctly 96.3% of the sera.

CONCLUSION

Our diagnostic criteria gave far better results in our population than the existing published criteria. This suggests that new criteria could be developed to improve WB interpretation in African settings.

Multicenter evaluation of a new automated fourth-generation human immunodeficiency virus screening assay with a sensitive antigen detection module and high specificity

Fourth-generation assays for the simultaneous detection of human immunodeficiency virus (HIV) antigen and antibody that were available on the international market until now have antigen detection modules with relatively poor sensitivity and produce a higher rate of false-positive results than third-generation enzyme immunoassays (EIAs). The new Cobas Core HIV Combi EIA with an improved sensitivity for HIV p24 antigen was compared to alternative fourth- and third-generation assays, the p24 antigen test, and HIV type 1 (HIV-1) RNA reverse transcriptase PCR (RT-PCR). A total of 94 seroconversion panels (n = 709 sera), samples from the acute phase of infection after seroconversion (n = 32), anti-HIV-1-positive specimens (n = 730) from patients in different stages of the disease, 462 subtyped samples from different geographical locations, anti-HIV-2-positive sera (n = 302), dilutions of cell culture supernatants (n = 62) from cells infected with different HIV-1 subtypes, selected performance panels from Boston Biomedica Inc., 7,579 unselected samples from blood donors, 303 unselected daily routine samples, 997 specimens from hospitalized patients, and potentially interfering samples (n = 1,222) were tested with Cobas Core HIV Combi EIA. The new assay showed a sensitivity comparable to that of the Abbott HIV-1 AG Monoclonal A for early detection of HIV infection in seroconversion panels. The mean time delay of Cobas Core HIV Combi EIA (last negative sample plus 1 day) in comparison to that for HIV-1 RT-PCR for 87 panels tested with both methods was 2.75 days. The diagnostic window was reduced with Cobas Core HIV Combi EIA by between 3.6 and 5.7 days from that for third-generation assays. The specificities of Cobas Core HIV Combi EIA in blood donors were 99.84 and 99.85% (after repeated testing). Overall, 30 repeatedly reactive false-positive results out of 10,031 HIV-negative samples were obtained with Cobas Core HIV Combi EIA. Our results show that a fourth-generation assay with improved specificity such as Cobas Core HIV Combi EIA is suitable for blood donor screening because of its low number of false positives and because it detects HIV p24 antigen with a sensitivity comparable to that of single-antigen assays.

Evaluation of a new combined antigen and antibody human immunodeficiency virus screening assay, VIDAS HIV DUO Ultra

Combined antigen and antibody screening (fourth-generation) assays reduce the diagnostic window period between the time of human immunodeficiency virus (HIV) infection and laboratory diagnosis by 4 days, on average, in comparison to antibody-only (third generation) enzyme immunoassays (EIAs). The aim of the present study was to assess whether the new VIDAS HIV DUO Ultra (Biomérieux, Marcy-l'Etoile, France) showed an improved sensitivity and specificity in comparison to licensed fourth-generation assays. A total of 16 seroconversion panels, 15 cell culture supernatants infected with different HIV type 1 (HIV-1) subtypes, and 257 potentially cross-reactive serum samples were tested with VIDAS DUO HIV Ultra, Genscreen Plus HIV Ag-Ab, Enzygnost HIV Integral, Enzymun-Test HIV Combi, Genscreen HIV 1/2, version 2 (third-generation EIA), and Genetic Systems HIV-1 Ag EIA (p24 antigen assay). VIDAS HIV DUO Ultra showed a comparable sensitivity to the single p24 antigen assay in seroconversion panels and a dilution series of virus lysates. The diagnostic window was reduced with VIDAS HIV DUO Ultra by 3.82 days, on average, in comparison with the fourth-generation assay with the lowest sensitivity of the antigen detection module. HIV-1 infection was detected 5.88 days earlier than with third-generation EIA. The mean time delay between reverse transcription-PCR and VIDAS HIV DUO Ultra was only 2.31 days. The specificity of fourth-generation assays after retesting ranged between 98.1 and 100%. In conclusion, VIDAS HIV DUO Ultra can replace single-antigen screening for laboratory diagnosis and screening of HIV infection in blood donors. There was no evidence for a second diagnostic window due to impaired sensitivity of the antibody detection module of all the fourth-generation EIAs evaluated in the present study. The specificity after initial and/or repeated testing of VIDAS HIV DUO Ultra was equivalent to that of a third-generation assay.

HBs antigen in children with suspicion of HIV infection

In order to evaluate the prevalence rate of HBs antigen in children with a suspicion of HIV infection, 103 children were tested for HBs antigen and HIV. The mean age of the children was 2 years. The prevalence of HBs antigen was 39.8 per cent in children and the HIV ELISA test was positive in 57.7 per cent. A correlation was found between carrier of HBs antigen and HIV ELISA positivity (p = 0.04, RR = 1.46; 1.06 < RR < 2.02). There was a high prevalence of HBs antigen in children with a suspicion of HIV infection. This calls for the promotion of antenal screening for HIV and HBV along with immunization against hepatitis B in newborns in our setting.

Seven human immunodeficiency virus (HIV) antigen-antibody combination assays: evaluation of HIV seroconversion sensitivity and subtype detection

In this study, we evaluated the performance of two prototype human immunodeficiency virus (HIV) antigen-antibody (Ag-Ab) combination assays, one from Abbott Laboratories (AxSYM HIV Ag-Ab) and the other from bioMerieux (VIDAS HIV Duo Ultra), versus five combination assays commercially available in Europe. The assays were Enzygnost HIV Integral, Genscreen Plus HIV Ag-Ab, Murex HIV Ag-Ab Combination, VIDAS HIV Duo, and Vironostika HIV Uniform II Ag-Ab. All assays were evaluated for the ability to detect p24 antigen from HIV-1 groups M and O, antibody-positive plasma samples from HIV-1 groups M and O, HIV-2, and 19 HIV seroconversion panels. Results indicate that although all combination assays can detect antibodies to HIV-1, group M, subtypes A to G, circulating recombinant form (CRF) A/E, and HIV-1 group O, their sensitivity varied considerably when tested using diluted HIV-1 group O and HIV-2 antibody-positive samples. Among combination assays, the AxSYM, Murex, and VIDAS HIV Duo Ultra assays exhibited the best antigen sensitivity (at approximately 25 pg of HIV Ag/ml) for detection of HIV-1 group M, subtypes A to G and CRF A/E, and HIV-1 group O isolates. However, the VIDAS HIV Duo Ultra assay had a lower sensitivity for HIV-1 group M and subtype C, and was unable to detect subtype C antigen even at 125 pg of HIV Ag/ml. The HIV antigen sensitivity of the VIDAS HIV Duo and Genscreen Plus combination assays was approximately 125 pg of HIV Ag/ml for detection of all HIV-1 group M isolates except HIV-1 group O while the sensitivity of Vironostika HIV Uniform II Ag-Ab and Enzygnost HIV Integral Ag-Ab assays for all the group M subtypes was >125 pg of HIV Ag/ml. Among the combination assays, the AxSYM assay had the best performance for detection of early seroconversion samples, followed by the Murex and VIDAS HIV Duo Ultra assays.

Long-term protease inhibitor-containing therapy results in limited improvement in T cell function but not restoration of interleukin-12 production in pediatric patients with AIDS

This study investigated whether immune restoration occurred in 26 human immunodeficiency virus (HIV) type 1-infected children treated first with indinavir for 16 weeks and then with combination antiretroviral therapy for >2 years. Compared with baseline, a significant, although modest, decrease in virus loads (maximum median, -0.86 log(10)) and increase in the number of CD4(+) lymphocytes, especially naive cells, were observed at several time points after 2 years. A maximum of 7% of treated children achieved undetectable viremia. There was a marked increase in the proliferative response and skin reactivity to recall antigens. However, responses to an HIV antigen remained depressed, and the production of interleukin-12 remained unchanged and abnormally low. The magnitude of virus suppression did not correlate with these measures of functional immune reconstitution. These findings suggest that long-term nonsuppressive antiretroviral therapy can induce limited improvement in immune function in pediatric AIDS patients and that the effect of suppressive treatments should be investigated.

Shortening of the diagnostic window with a new combined HIV p24 antigen and anti-HIV-1/2/O screening test

Because antibodies to the human immunodeficiency virus (HIV) are absent in the very early phase of HIV infection, there remains a slight residual risk for HIV transmission by blood donations by viremic but antibody negative donations. To shorten the diagnostic window between infection and the detection of antibodies, Enzygnost HIV Integral (Dade Behring, Germany) was developed. With this new test, HIV p24 antigen and HIV antibodies can be detected simultaneously in a single test. In a multicenter study the new screening assay has been compared with various tests that detect only HIV antibodies or HIV p24 antigen and with assays which permit a simultaneous detection of HIV antigen and HIV antibodies. The new assay showed 100% sensitivity for the detection of antibodies to HIV-1, groups M (n=1102) and O (n=55), and HIV-2 (n=289). In 23 out of 52 seroconversion panels, seroconversion was detected 2-18 days earlier with the new combined antigen/antibody test compared to single antibody tests. All samples from a viral load panel (n=451), all samples containing p24 antigen (n=302), and all but one of the cell culture supernatants (n=38) infected with various HIV-1 subtypes or HIV-2 were identified reliably by the new test. The specificity of the assay for 4002 unselected blood donors was 99.78% initially and 99.80% after retesting. Potentially interfering factors had no systematic influence on specificity. By testing for p24 antigen, which is present prior to the onset of antibody production in some cases of recent HIV infection, the new assay reduces the diagnostic window as compared to third generation screening assays, thus permitting an earlier diagnosis of HIV infection.