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Background In France, there are no consistent data estimating hepatitis delta virus (HDV) prevalence in the general population. Objectives To better characterize HDV/HBV infection and its trends over a 15-years period from 1997 to 2011, we used data retrieved from the National Epidemiological Donors database including viral and demographic characteristics of all French HBV infected blood donors. Study design Of the 39,911,011 donations collected over the 15 year-study-period, 6214 (1.56 in 10 4 donations) were confirmed positive for HBV from which 72.3% were tested for HDV antibodies (Ab). HDV viral load was performed using a real-time PCR assay on positive HDV Ab samples and HDV genotype determined for each positive viremic sample. Results Among the 4492 HBV donations, 89 (1.98%) were HDV Ab positive. After being stable around 1.1% from 1997 to 2005, this rate has continuously increased to reach 6.5% in 2010, before declining to 0.85% in 2011. Of the 61 investigated HDV Ab positive individuals, 22.9% were viremic with a viral load ranging from 10 4 to 9.8 × 10 7 copies mL −1 . Genotyping revealed 12 HDV-1, 1 HDV-6 and 1 HDV-7 in accordance with the geographical origin of individuals. Conclusion Such a study gives unexpected features of HBV–HDV infection in the population of blood donors which is a priori, a healthy population. The increase of HDV prevalence mainly linked to migration of population from endemic countries, demonstrates that there is still no complete control of HBV infection and must encourage HBV vaccination campaigns and systematic screening for HDV in HBV-infected.

Background: the heterogeneity of the TT virus (TTV) DNA prevalence values reported from comparable human cohorts suggests that diagnostic PCR protocols still require to be optimized. Objectives: to design TTV PCR primer sets with low genotype restriction and to compare their performances with commonly used amplification systems. Study design: we compared full length TTV genomic sequences and identified conserved nucleotide patterns in the 5′ and 3′ non-coding regions of the viral genome. This permitted to design two new primer sets usable for the PCR amplification of the most divergent human isolates of TTV described to date. The performances of these amplification systems were compared with those of three other PCR systems earlier used for prevalence studies. Results: the primer systems P5Bx and P3Bx exhibited higher PCR scores than the other systems tested; 14 to 34% improvement values were obtained, and divergent positive results of earlier described PCR systems were confirmed systematically by our new detection assays. Conclusions: an optimized detection of TT virus DNA is a pre-requisite for the accurate epidemiological survey of viral infection and for the realization of phylogenetic studies. Such PCR systems with low genotype restriction will be helpful in the future for a better knowledge of natural history of TT virus infection.

Background: TT virus (TTV) is a recently discovered virus, which is not related to any other known virus infecting humans. Objectives: To investigate: (i) the world-wide distribution of the three major TTV genotypes; and (ii) the possible routes of viral transmission. Study design: (i) The phylogenetic distribution of 494 TTV isolates originating from 31 countries was analysed, using partial ORF1 sequences. (ii) Faeces samples (n=22) and saliva samples (n=72) from French individuals were tested for the presence of TTV DNA. (iii) Viral titres in paired serum and saliva samples were compared. Results: (i) Genotypes 1, 2 and 3 were distributed world-wide, with a high proportion of type 1 in Asia (71%) and no type 3 identified in Africa to date. In the USA, 77% of isolates were grouped in four clusters only (genetic distances