Droplet digital PCR assay as an innovative and promising highly sensitive assay to unveil residual and cryptic HBV replication in peripheral compartment

: Droplet digital PCR is an innovative and promising approach for highly sensitive quantification of nucleic acids that is being increasingly used in the field of clinical virology, including the setting of hepatitis B virus (HBV). Here, we comprehensively report a robust and reproducible ddPCR assay for the highly sensitive quantification of serum HBV-DNA. The assay showed a limit of detection of 4 copies/ml (<1IU/ml) by Probit analysis, showed a good linearity (R2 = 0.94) and a high intra- and inter-run reproducibility with differences between the values obtained in the same run or in two independent runs never exceeding 0.14logcopies/mL and 0.21logcopies/mL, respectively. By analysing serum samples from chronically HBV infected patients (mostly under antiviral treatment), ddPCR successfully quantified serum HBV-DNA in 89.8% of patients with detectable serum HBV-DNA < 20 IU/mL [equivalent to <112copies/ml] by classical Real-Time PCR assay, with a median (IQR) of 8(5-14)IU/mL [45(28-78)copies/ml], and in 66.7% of patients with undetectable serum HBV-DNA, with a median (IQR) of 5(4-9)IU/mL [28(20-50)copies/ml]. Similarly, by analysing serum samples from patients with a serological profile compatible with occult HBV infection (anti-HBc+/HBsAg-), ddPCR successfully quantified serum HBV-DNA in 40% of patients with a median (IQR) value of 1(1-2)IU/mL [5(5-11)copies/ml], in line with the extremely limited viral replication typically observed in occult HBV infection. Overall, the availability of assays for the highly sensitive quantification of serum HBV-DNA can provide an added value in optimizing the diagnosis of occult hepatitis B infection, improving the therapeutic management of chronically HBV infected patients, also in the light of innovative drugs (upcoming in clinical practise) aimed at achieving HBV functional cure

Formal Modeling and Discrete-Time Analysis of BPEL Web Services

International audienceWeb services are increasingly used for building enterprise information systems according to the Service Oriented Architecture (SOA) paradigm. We propose in this paper a tool-equipped methodology allowing the formal modeling and analysis of Web services described in the BPEL language. The discrete-time transition systems modeling the behavior of BPEL descriptions are obtained by an exhaustive simulation based on a formalization of BPEL semantics using the Algebra of Timed Processes (ATP). These models are then analyzed by model checking value-based temporal logic properties using the CADP toolbox. The approach is illustrated with the design of a Web service for GPS navigation