What is really ongoing during occult HBV reactivation?

International audienc

Rolling Circle Amplification, a Powerful Tool for Genetic and Functional Studies of Complete Hepatitis B Virus Genomes from Low-Level Infections and for Directly Probing Covalently Closed Circular DNA▿

Complete characterization of the biological properties of hepatitis B virus (HBV) variants requires the generation of full-length genomes. The aim of this study was to develop new tools for the efficient full-length genome amplification of virus from samples with low viral loads. Rolling circle amplification (RCA) was used to amplify full-length HBV genomes from both sera and liver biopsy samples from chronic HBV carriers. Serum-derived relaxed circular HBV DNA could be amplified only after completion and ligation of plus-strand DNA. Covalently closed circular DNA (cccDNA) from liver biopsies could be amplified directly from as few as 13 copies, using RCA, followed by a full-length HBV PCR. Three serial liver biopsy samples were obtained from a lamivudine-resistant patient who cleared detectable serum HBV after adefovir dipivoxil was added to the lamivudine therapy and then seroconverted to anti-HBs. Only the genomes from the last biopsy specimen obtained after the emergence of lamivudine resistance contained the lamivudine resistance-associated mutations rtL180M and rtM204V (“rt” indicates reverse transcriptase domain). Defective genomes were also found in this biopsy sample. Genomes cloned from the liver biopsy specimens were transfected into HuH7 cells to study their replication competence and their susceptibility to lamivudine. RCA is a powerful tool for amplifying full-length HBV genomes and will be especially useful for the study of occult or inactive HBV infections and patients undergoing antiviral treatment. It can also be used to probe HBV cccDNA, the crucial intermediate in viral persistence and the archive of resistance mutations

Un matériau unique pour détecter le formaldéhyde et trouver ses sources d’émission

Le formaldéhyde est le principal polluant de l’air intérieur. Du fait de sa présence ubiquiste liée aux nombreuses sources d’émission, la teneur de ce polluant nocif dans l’air intérieur est représentative d’une bonne ou d’une mauvaise qualité de l’air. Les réglementations en matière d’exposition chronique au formaldéhyde en France sont les plus avancées dans toute l’Europe. Gérer la qualité de l’air intérieur dans les établissements publics ou dans les habitats nécessite donc non seulement de détecter et de mesurer la teneur en formaldéhyde dans l’air mais également de trouver les sources d’émission pour les éradiquer. Un exemple est montré ici avec l’utilisation d’un capteur nanoporeux appliqué aux fonctions multiples de détection