Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients.

OBJECTIVES: SARS-CoV-2 antibody assays are needed for serological surveys and as a complement to molecular tests to confirm COVID-19. However, the kinetics of the humoral response against SARS-CoV-2 remains poorly described and relies on the performance of the different serological tests. METHODS: In this study, we evaluated the performance of six CE-marked point-of-care tests (POC) and three ELISA assays for the diagnosis of COVID-19 by exploring seroconversions in hospitalized patients who tested positive for SARS-CoV-2 RNA. RESULTS: Both the ELISA and POC tests were able to detect SARS-CoV-2 antibodies in at least half of the samples collected seven days or more after the onset of symptoms. After 15 days, the rate of detection rose to over 80% but without reaching 100%, irrespective of the test used. More than 90% of the samples collected after 15 days tested positive using the iSIA and Accu-Tell® POC tests and the ID.Vet IgG ELISA assay. Seroconversion was observed 5 to 12 days after the onset of symptoms. Three assays suffer from a specificity below 90% (EUROIMMUN IgG and IgA, UNscience, Zhuhai Livzon). CONCLUSIONS: The second week of COVID-19 seems to be the best period for assessing the sensitivity of commercial serological assays. To achieve an early diagnosis of COVID-19 based on antibody detection, a dual challenge must be met: the immunodiagnostic window period must be shortened and an optimal specificity must be conserved.

Detection of Mycobacterium tuberculosis in paucibacillary sputum: performances of the Xpert MTB/RIF ultra compared to the Xpert MTB/RIF, and IS6110 PCR.

The Xpert MTB/RIF Ultra assay has recently been launched to improve the detection of smear negative disease. This retrospective study compares the sensitivity of Xpert MTB/RIF Ultra with that of Xpert MTB/RIF tests and IS6110 real-time PCR in sputum. Diagnostic performance of three molecular tests was evaluated using 48 culture-positive clinical respiratory specimens diluted to obtain paucibacillary sputum specimens. Xpert MTB/RIF Ultra had the highest sensitivity of 100% compared to 42% (P < 0.001) for Xpert MTB/RIF and 64.5% (P = 0.02) for IS6110-PCR. All "very low" or "low" positive specimens using Xpert MTB/RIF Ultra were tested positive using IS6110-PCR, but 35.4% were found negative using Xpert MTB/RIF. Xpert MTB/RIF Ultra is more sensitive than the two other tests for sputum with a low bacterial load. Adding detection of IS6110 and IS1081 to rpoB, is a key evolution of the assay and improves the detection of Mycobacterium tuberculosis' DNA in paucibacillary sputum.

Analytical and field evaluation of the Biocentric Generic HCV assay on open polyvalent PCR platforms in France and Cambodia.

BACKGROUND: Implementation of affordable methods for HCV viremia is a key priority for identifying individuals who need treatment among persons screened positive for HCV antibodies. Different HCV PCR assays for use on open polyvalent PCR platforms are currently commercially available but studies evaluating the performances of these nucleic acid tests are needed. OBJECTIVES: In the present study, we evaluated the analytical and clinical performances of a recently developed HCV RNA PCR assay for detection and quantification of HCV viremia. STUDY DESIGN: In this study the Biocentric Generic HCV PCR was compared to the Roche Cobas AmpliPrep/Cobas TaqMan HCV RNA assay. Analytical and clinical performances was evaluated on reference materials and HCV plasma samples collected in 141 patients attending at the Montpellier University Hospital in France. Field evaluation was performed on samples collected in 185 patients attending at Medical Laboratory, Institut Pasteur in Cambodia. RESULTS: The lower limit of detection ranged from 50 HCV RNA IU/ml to 300 HCV RNA IU/ml using four different Diasorin and Qiagen automated or manual extraction methods. The specificity (CI) and sensitivity of the assay were 100% (92.5-100), and 98.7% (92.3-99.9), respectively, in France, and 100% (95.5-100), and 100% (94.4-100%), respectively, in Cambodia. Bland-Altman analysis shown good agreement between the two assays including for genotypes 6 HCV, which represent the majority of HCV isolates in Cambodia. CONCLUSIONS: The Biocentric Generic HCV assay has shown overall satisfactory analytical performances and a close agreement to the Cobas HCV assay on clinical specimens collected in France and Cambodia. There is an urgent need to further evaluate commercial assays dedicated to HCV detection and quantification using open polyvalent PCR platforms in different settings.

Staging of recent HIV-1 infection using Geenius rapid confirmatory assay compared to INNO-LIA, New Lav and Blot 2.2 assays.

BACKGROUND: Besides confirmation of HIV seropositivity, Western Blot (WB) assays play an important role for identification of recent infection based on incomplete antibody reactivity and lack of p31 band. OBJECTIVES: We evaluated the capacities of the Geenius™ HIV1/2 Confirmatory Assay (Bio-Rad), a new generation rapid confirmatory assay based on immune-chromatography and automated reading, for staging of HIV-1 infection. STUDY DESIGN: Sixteen samples collected during early HIV-1 infections (Fiebig stage III-VI) were tested using the Geenius assay, and compared to HIV Blot 2.2 WB assay (MP Diagnostics), New Lav Blot I WB assay (Bio-Rad) and INNO-LIA™ HIV I/II Score Dot Blot assay (Fujirebio). Results obtained with Geenius and INNO LIA in 47 newly diagnosed chronic HIV-1 infections were also compared. RESULTS: The p24 band was less frequently detected in early HIV-1 infections using the Geenius (3/16) compared to the New Lav (15/16, p<0.0001), INNO-LIA (13/16, p=0.0011), and Blot 2.2 (13/16, p=0.0011). Testing samples collected during chronic infection allowed to confirm that p31 band and complete Gag, Pol, Env profiles were less frequently observed using the Geenius assay compared to the INNO LIA assay (p=0.027 for p31, and p=0.0015 for complete profile). CONCLUSIONS: The Geenius assay is a simple and rapid test showing a high sensitivity to detect Env bands and to confirm HIV-1 seropositivity during the early phases of infection. However, this test is less suitable for distinguishing between later stages of acute and chronic infections because of a reduced sensitivity to detect the p31 and p24 bands compared to INNO LIA and New Lav assays.

Impact of T cell activation, HIV replication and hepatitis C virus infection on neutrophil CD64 expression.

BACKGROUND: Overexpression of the Fc receptor CD64 on neutrophils is associated with innate immune response and bacterial infections. During HIV infection a large set of immune disorders including T-lymphocyte over-activation, microbial translocation, impairment of neutrophil functions, and immunodeficiency may interplay with neutrophil CD64 expression. METHODS: Associations of neutrophil CD64 expression with CD8+ T cell activation, CD4+ T cells number, HIV, and HCV replications were investigated in HIV infected patients using a standardized method. RESULTS: Higher neutrophil CD64 expression was observed in HIV infected subjects compared to healthy controls (0.91 vs. 0.75, P < 0.001). Among 115 HIV infected patients, nine (8.8%) had a CD64 expression over the clinical threshold as calculated against bead standard (i.e., 1.5). HIV viremic patients were more likely to have an index above 1.5 (OR: 6.68, P values: 0.01). A trend for correlation between CD64 expression and CD8 T cell activation was observed (P values: 0.08). Blood CD4+ T lymphocyte depletion and HCV replication did not affect neutrophil CD64 expression. CONCLUSIONS: HIV infection and HIV replication are associated with up-regulation of neutrophil CD64. CD64 overexpression above the clinical threshold was observed in a minor proportion of HIV infected individuals treated by antiretroviral therapy and may be a marker of neutrophil activation related to non-AIDS-linked comorbidities. © 2016 International Clinical Cytometry Society.

Circulating FVIII-specific IgG, IgA and IgM memory B cells from haemophilia A patients.

INTRODUCTION: Approximately, 25% of haemophilia A (HA) patients treated by factor VIII (FVIII), develop antibodies, known as inhibitors, neutralizing the activity of infused FVIII. This immune response involves B cells (BC), including FVIII-specific memory B cells (MBC). Production of anti-FVIII antibodies after stimulation of FVIII-specific MBC suggests a role of these cells in the immune response to FVIII. Animal models allowed the study of circulating FVIII-specific cells, however few data are available on HA patients. AIM AND METHODS: In the present study, we simultaneously detected, via ELISpot assay, different isotypes of MBC in the blood of HA patients, after polyclonal activation. Patients included: three with active inhibitors; three with a history of inhibitors; six without any past or active inhibitor. RESULTS: FVIII-specific MBC were detected in peripheral blood of HA patients: (i) patients with active inhibitors (IgG: 4-5.2/10(6) BC; IgA: 2.9-4/10(6) BC) (ii) patients with a past of inhibitors (no IgG BC; IgA: 5-7.5/10(6) BC) (iii) patients without inhibitors (no IgG BC or IgA BC except one patient had two FVIII-specific IgA BC/10(6) BC). CONCLUSION: FVIII-specific IgA MBC were detected in HA patients with past and current immune responses against FVIII and FVIII-specific IgG MBC were found only in those with positive inhibitors. This study shows the possibility to detect and characterize easily and simultaneously the MBC from patient blood and that MBC seem different according to anti-FVIII immune history. It could be a useful tool to study anti-FVIII response and Immune Tolerance Induction cellular mechanisms.

Association between breast milk fatty acids and HIV-1 transmission through breastfeeding.

A residual mother-to-child transmission of HIV through breastfeeding persists despite prophylaxis. We identified breast milk fatty acids (FA) associated with postnatal HIV transmission through breastfeeding in a case-control study. Cases (n=23) were HIV-infected women with an infant who acquired HIV after 6 weeks of age. Controls (n=23) were matched on infant׳s age at sample collection. Adjusting for maternal antenatal plasma CD4 T cell count, cis-vaccenic acid (18:1n-7) and eicosatrienoic acid (20:3n-3) were associated with HIV transmission in opposite dose-response manner: OR (tertile 3 versus tertile 1): 10.8 and 0.16, p for trend=0.02 and 0.03, respectively. These fatty acids correlated with HIV RNA load, T helper-1 related cytokines, IL15, IP10, and ß2 microglobulin, positively for cis-vaccenic acid, negatively for eicosatrienoic acid. These results suggested a change in FA synthesis by mammary gland cells leading to increased cis-vaccenic acid in milk of mothers who transmitted HIV to their infant during breastfeeding.

Diagnostic accuracy of IL-2 for the diagnosis of latent tuberculosis: a systematic review and meta-analysis.

We conducted a systematic review and meta-analysis to evaluate the diagnostic potential of interleukin-2 (IL-2) as biomarkers for the diagnosis of latent tuberculosis. Related studies were identified through searches of PubMed, Embase, Web of Science, and complementary manual searches up to December 30, 2013. We used standard methods recommended for meta-analyses of diagnostic test evaluations. The analysis was based on a summary receiver operating characteristic (SROC) curve. Meta-regression analysis was used to assess the effects of some confounding factors on the results of the meta-analysis. The potential presence of publication bias was tested using the Deeks' funnel plots. The pooled estimates of IL-2 for latent tuberculosis infection (LTBI) diagnosis were as follows: sensitivity, 0.81 [95 % confidence interval (CI), 0.60 to 0.92]; specificity, 0.95 (95 % CI, 0.90 to 0.97); positive likelihood ratio (PLR), 15.2 (95 % CI, 8.1to 28.4); negative likelihood ratio (NLR), 0.20 (95 % CI, 0.09 to 0.47). We found that the SROC curve is positioned near the upper left corner of the curve and the area under the curve (AUC) was 0.96 (95 % CI, 0.94 to 0.98). In conclusion, according to the meta-analysis, IL-2 is a valid marker for the diagnosis of LTBI. When there is no definite gold standard for the diagnosis of LTBI, IL-2 release assay in addition to interferon-gamma release assays (IGRAs) can improve the ability of IGRAs to identify individuals with LTBI.

Combining rapid diagnostic tests and dried blood spot assays for point-of-care testing of human immunodeficiency virus, hepatitis B and hepatitis C infections in Burkina Faso, West Africa.

People screened for human immunodeficiency virus (HIV) using rapid diagnostic tests (RDTs) in Africa remain generally unaware of their status for hepatitis B (HBV) and hepatitis C (HCV) infections. We evaluated a two-step screening strategy in Burkina Faso, using both HIV RDTs and Dried Blood Spot (DBS) assays to confirm an HIV-positive test, and to test for HBV and HCV infections. HIV counselling and point-of-care testing were performed at a voluntary counselling and testing centre with HBV, HCV status and HIV confirmation using DBS specimens, being assessed at a central laboratory. Serological testing on plasma was used as the reference standard assay to control for the performance of DBS assays. Nineteen out of 218 participants included in the study were positive for HIV using RDTs. A fourth-generation HIV ELISA and immunoblot assays on DBS confirmed HIV status. Twenty-four out of 25 participants infected with HBV were found positive for hepatitis B surface antigen (HBsAg) using DBS. One sample with a low HBsAg concentration on plasma was not detected on DBS. Five participants tested positive for HCV antibodies were confirmed positive with an immunoblot assay using DBS specimens. Laboratory results were communicated within 7 days to participants with no loss to follow up of participants between the first and second post-test counselling sessions. In conclusion, DBS collection during HIV point-of-care testing enables screening and confirmation of HBV, HCV and HIV infections. Diagnosis using DBS may assist with implementation of national programmes for HBV, HCV and HIV screening and clinical care in middle- to low-income countries.

Long-term hepatitis B virus surface antigen decay in HIV-1/hepatitis B virus-coinfected adults initiating a tenofovir-containing regimen.

Hepatitis B virus (HBV) surface antigen (HBsAg) decay was explored in HIV-1- and HBV-coinfected patients beginning antiretroviral (ARV) therapy containing tenofovir disoproxil fumarate (TDF). The mean HBsAg decay was 0.38 log(10) IU/ml/year (95% confidence interval [CI], 0.71 to 0.05) in 18 patients with sustained plasma HIV-1 RNA suppression and 0.15 log(10) IU/ml/year (0.21 to 0.09) in 12 patients experiencing HIV-1 virologic failure due to suboptimal adherence to ARV (P = 0.17). We estimated that six of these 18 patients will attain HBsAg values below 10 IU/ml after 10 years of treatment.

Investigation of memory B cell responses to hepatitis B surface antigen in health care workers considered as non-responders to vaccination.

Up to 20% of health care workers are considered as non-responders to hepatitis B vaccination (anti-HBs<10 m UI/ml in serum). We have explored memory B cells differentiated in vitro into anti-HBs antibody-secreting cells (anti-HBs-SCs) by ELISPOT assay. Anti-HBs-SCs were detected in vaccinated responders (n = 11) and non-responders (n = 10) but IgG anti-HBs-SCs were significantly lower in the non-responder group (p<0.001). Low amounts of HBs antibodies were also quantified by ELISA in non-responders' sera. These results indicate that a suboptimal B cell response exists in non-responders to HBV vaccination. This B cell response may mediate a protection against clinically significant breakthrough hepatitis B infection.

Comprehensive proteomic analysis of the human milk proteome: contribution of protein fractionation.

In-depth analysis of the milk proteome by mass spectrometry is challenged by the presence of few high-abundance proteins that interfere with the detection of lower-abundance proteins. Here, we evaluated the proteomic analysis of milk samples following a strong anion exchange fractionation procedure using denaturating conditions ensuring the disruption of protein-protein interactions. Crude whey or skim milk and their different resulting fractions were analyzed by protein chip array mass spectrometry. Using protein chip array mass spectrometry, several high-abundance proteins were localized in distinct fractions increasing the total number of unique peptides and proteins detected. This total number increased by about 20-30% by combining different chromatographic surface arrays used for capture. Reproducible results were obtained in human skim milk and whey; however this approach was not successful with milk fat globule membrane and required refinement. Hence, milk profiling by anion exchange fractionation combined to protein chip array mass spectrometry represents a promising tool to detect unknown low-abundance milk proteins that may ultimately prove useful as biomarkers of diseases transmitted by breastfeeding.