Search Results (4)

Discrepancies in human hepatitis delta virus (HDV) genotypes impact the virus’ biological behavior, clinical manifestation, and treatment response. Herein, this report aims to explore the role of recombination in the worldwide genotypic distribution and genetic diversity of HDV. Three-hundred-forty-eight human HDV full-length genomic sequences of ~1678 nt in length, isolated in twenty-eight countries worldwide between 1986 and 2018, were analysed. Similarity analysis and recombination mapping were performed, and forty-eight recombination events were identified, twenty-nine of which were isolated from Kyrgyzstan and determined to be involved in the diversity and extension of HDV sub-genotypes. HDV recombination occurred only between the genetically close genotypes (genotype 5 and genotype 2) or mainly within genotype 1, suggesting the complex replicative molecular mechanisms of HDV-RNA. The global distribution and classification of HDV genotypes have been updated, indicating that HDV recombination is one of the driving forces behind the biodiversity and the evolution of human HDV genomes. The outcome analysis suggests that the expansion of HDV sub-genotypes and the complex recombination networks might be related to the genomic character of Kyrgyzstan circulating strains and extensive mobility within countries and across borders. These findings will be of great importance in formulating more effective public health HDV surveillance strategies and guiding future molecular and epidemiological research to achieve better clinical outcomes. Full article

Modern metagenomic approaches enable the effective discovery of novel viruses in previously unexplored organisms. Termites are significant ecosystem converters and influencers. As with the majority of tropical forest insects, termites are studied insufficiently, and termite virome remains especially understudied. Here, we studied the virome of lichenophagous and mycophagous termites (Hospitalitermes bicolor, Macrotermes carbonarius and Odontotermes wallonensis) collected in the Cat Tien National Park (Vietnam). We assembled four full genomes of novel viruses related to Solemoviridae, Lispiviridae, Polycipiviridae and Kolmioviridae. We also found several contigs with relation to Chuviridae and Deltaflexiviridae that did not correspond to complete virus genomes. All the novel viruses clustered phylogenetically with previously identified viruses of the termites. Deltaflexi-like contigs were identified in the fungi-cultivating M. carbonarius and showed homology with viruses recently discovered in the edible basidiomycete mushrooms. Full article

Human hepatitis D virus (HDV) depends on hepatitis B virus co-infection and its glycoproteins for infectious particle formation. HDV was the sole known deltavirus for decades and believed to be a human-only pathogen. However, since 2018, several groups reported finding HDV-like agents from various hosts but without co-infecting hepadnaviruses. In vitro systems enabling helper virus-independent replication are key for studying the newly discovered deltaviruses. Others and we have successfully used constructs containing multimers of the deltavirus genome for the replication of various deltaviruses via transfection in cell culture. Here, we report the establishment of deltavirus infectious clones with 1.2× genome inserts bearing two copies of the genomic and antigenomic ribozymes. We used Swiss snake colony virus 1 as the model to compare the ability of the previously reported “2× genome” and the “1.2× genome” infectious clones to initiate replication in cell culture. Using immunofluorescence, qRT-PCR, immuno- and northern blotting, we found the 2× and 1.2× genome clones to similarly initiate deltavirus replication in vitro and both induced a persistent infection of snake cells. The 1.2× genome constructs enable easier introduction of modifications required for studying deltavirus replication and cellular interactions. Full article

Chronic hepatitis delta virus infection (CHD) is a condition arising from super-infection of hepatitis B virus (HBV)-infected patients, resulting in a more rapid advance in liver pathology and hepatocellular carcinoma than is observed for HBV mono-infection. Although hepatitis delta virus (HDV) is structurally simple, its life cycle involves the complex participation of host enzymes, HBV-derived surface antigen (HBsAg), and HDV-auto-ribozyme and hepatitis delta antigen (HDAg) activities. Unsatisfactory clinical trial results with interferon-based therapies are motivating researchers to adjust and redirect the approach to CHD drug development. This new effort will likely require additional structural and functional studies of the viral and cellular/host components involved in the HDV replication cycle. This review highlights recent work aimed at new drug interventions for CHD, with interpretation of key pre-clinical- and clinical trial outcomes and a discussion of promising new technological approaches to antiviral drug design. Full article