Analytical validation of hepatitis B core-related antigen (HBcrAg) using dried blood spots (DBS)

Limited access to nucleic acid testing (NAT) to quantify HBV DNA levels, an essential tool to determine anti-HBV treatment eligibility, represents a significant barrier to scale up HBV diagnostic services in resource-limited countries. Hepatitis B core-related antigen (HBcrAg) has the potential to become an affordable alternative because of its low cost (US$ <15/assay) and strong correlation with HBV DNA levels in treatment-naïve patients. However, the current assay requires plasma or serum. To further facilitate its application to decentralized settings, we developed and evaluated a standardized procedure to quantify HBcrAg using dried blood spots as a tool to diagnose HBV-infected people with high viraemia. We evaluated the following elution method optimized to quantify HBcrAg: suspension of a punched blood-soaked disc (11 mm) of Whatman 903 Protein Saver Card in 450 µL of PBS 0.05% Tween 20, followed by an incubation for 4 h at room temperature and a centrifugation at 10,000 g for 10 minutes. 150 µL of DBS eluate was used to quantify HBcrAg using chemiluminescent enzyme immunoassay (LUMIPULSE^® G600II, Fujirebio). The limit of detection of dried blood spot HBcrAg in relation with HBV DNA levels was 19,115 IU/mL across the five major HBV genotypes (A/B/C/D/E). A strong linear correlation was confirmed between dried blood spot HBcrAg and HBV DNA levels (r = 0.94, p < 0.0001) in samples with high viral loads (range: 3.7-7.0 log IU/mL). The coefficient of variation ranged between 4.0-11.2% for repeatability and 3.9-12.2% for reproducibility. Analytical specificity was 100% (95% CI: 83.9-100%) in HBV-negative samples. Using our elution method, it may be possible to identify HBV-infected patients with high viraemia who need antiviral therapy using dried blood spot and HBcrAg. A large-scale clinical validation is warranted in resource-limited countries.

Biomarkers for the early stages of clinical development in Alzheimer's disease

As the failure of several recent Phase III drug development programmes bears witness, the clinical development of "disease-modifying" drugs in Alzheimer's disease has been confronted with challenging methodological difficulties. Taking into account the financial stakes involved taking drug candidates to the Phase III stage of development, and the risk of investing time and resources fruitlessly in the evaluation of poor candidate drugs, the crucial decision remains whether to proceed from Phase II to Phase III (Go/Nogo). The aim of Phase II studies is to select a molecule likely to be effective in Phase III, but also to eliminate candidate-drugs with an inadequate effect. No consensus currently exists on the best possible design of Phase II studies to inform the Go/Nogo decision optimally. The challenges in choosing the best study design relate to the target population, the end-point criteria used, in particular the use of biomarkers, the experimental protocol, and the study duration. The objective of the Round Table (RT) was to gather the opinions of French experts from the academic, industrial, and regulatory world in order to arrive at a consensus recommendation for the best possible design to be used in Phase II studies in Alzheimer's disease.

Urinary prostaglandin metabolites evaluation for activity monitoring in inflammatory bowel disease

Inflammatory bowel diseases cause chronic intestinal inflammation, including Crohn's disease (CD) and ulcerative colitis (UC). Prostaglandin E-major urinary metabolite (PGE-MUM) is a urine biomarker for disease activity in IBD. This study evaluated PGE-MUM performance for predicting an active disease in patients with CD and UC. We also compared PGE-MUM performances to fecal calprotectin (FC) and blood C-reactive protein (CRP). A total of 214 patients were included from two University Hospitals in Italy and France. One hundred and twenty-one patients with CD and 86 with UC were included. We compared PGE-MUM, FC, and CRP in patients. In the CD group, PGE-MUM AUC for predicting an active disease was 0.659 with 46% sensitivity and 80% specificity. FC AUC was 0.957 with 98% sensitivity and 80% specificity. CRP AUC was 0.619, with 49% sensitivity and 76% specificity. In the UC group, PGE-MUM AUC was 0.693 with 37% sensitivity and 97% specificity. FC AUC was 0.916 with 78% sensitivity and 95% specificity. FC was superior to the PGE-MUM in CD (p < 0.0001) and UC (p = 0.003), indicating a higher performance in predicting an active disease. The Combination of both markers gave an AUC of 0.926 in UC and 0.952 in CD, comparable to that observed with FC alone. Cluster analysis revealed distinct inflammatory patterns with compact and homogenous character, with two endophenotypes based on biomarkers for UC and three for CD showing a between-class variance of 52% and 65%, respectively. PGE-MUM and FC are associated with clinical disease activity in UC and CD. PGE-MUM does not perform better than FC alone. These two markers' combination showed three distinct patterns in CD and two in UC. Combining PGE-MUM and FC may improve the assessment of inflammation profiles in IBD and constitute a promising way for personalized approaches.

Antibody avidity measurement and immune complex dissociation for serological diagnosis of vertically acquired HIV-1 infection

Differences in avidity between HIV-1 antibodies transmitted passively and antibodies synthesized by children born to HIV-1-positive mothers can be measured using a commercially available competitive enzyme immunoassay kit. The avidity determination method is based on the competition between an anti-HIV-1-peroxidase-labeled antibody at a stable and known concentration and the anti-HIV-1 antibodies (IgA, IgG, IgM) present in the child's serum at various and increasing dilutions. The shift in the competition/dilution curves between serum samples taken at the third and the sixth month of the child's life showed either the loss or the synthesis of anti-HIV-1 antibodies. The antibody avidity determination combined with a test detecting free or complexed p24 antigen is a workable and inexpensive serological method for the follow-up of children born to seropositive mothers. Combining these two complementary methods, HIV-1 infection has been established at 6 months of age in 13 of 13 infants, and positive results were confirmed by coculture and by PCR. An HIV-1 infection was excluded at 6 months of age in 17 of 17 infants, results otherwise confirmed by virological and clinical follow-up. These new and convenient approaches to the diagnosis of vertically acquired HIV-1 could be used worldwide, including in developing countries.