Human astrovirus types 1, 4 and 5 circulating among children with acute gastroenteritis in a rural Brazilian state, 2010-2016

This study combined conventional epidemiology of human astroviruses. From 2010 to 2016, 232 stool samples from children under 5 years of age were screened using NGS and conventional RT-PCR followed by genetic analysis in order to investigate the genotypic diversity of classical human astrovirus (HAstV) circulating in Tocantins State, Brazil. HAstV was detected in 16 cases (6.9%). Seven specimens (43.7%; 7/16) were positive according RT-PCR and next-generation sequencing (NGS) to investigate the molecular to both NGS and RT-PCR. NGS and RT-PCR individually revealed six (37.5%; 6/16) and three (18.8%; 3/16) additional positive samples, respectively. Sequencing of the HAstV-positive samples revealed HAstV-1a (9/16), HAstV-4c (3/16), and HAstV-5c (4/16) lineages.

Genetic and Phenotypic Characterization of Cryphonectria hypovirus 1 from Eurasian Georgia

Cryphonectria hypovirus 1 (CHV-1) infects the chestnut blight fungus Cryphonectria parasitica and acts as a biological control agent against this harmful tree disease. In this study, we screened the recently characterized C. parasitica population in Eurasian Georgia for the presence of CHV-1. We found 62 CHV-1 infected C. parasitica isolates (9.3%) among a total of 664 isolates sampled in 14 locations across Georgia. The prevalence of CHV-1 at the different locations ranged from 0% in the eastern part of the country to 29% in the western part. Sequencing of two specific regions of the viral genome one each in ORFA and ORFB revealed a unique CHV-1 subtype in Georgia. This subtype has a recombinant pattern combining the ORFA region from the subtype F2 and the ORFB region from subtype D. All 62 viral strains belonged to this Georgian CHV-1 subtype (subtype G). The CHV-1 subtype G strongly reduced the parasitic growth of C. parasitica isolates from Georgia, with a more severe effect on the European genepool compared to the Georgian genepool. The CHV-1 subtype detected in Georgia provides a valuable candidate for biological control applications in the Caucasus region.

Genome sequencing of an Indian peste des petits ruminants virus isolate, Izatnagar/94, and its implications for virus diversity, divergence and phylogeography

Peste des petits ruminants is an important transboundary disease infecting small ruminants. Genome or gene sequence analysis enriches our knowledge about the evolution and transboundary nature of the causative agent of this disease, peste des petits ruminants virus (PPRV). Although analysis using whole genome sequences of pathogens leads to more precise phylogenetic relationships, when compared to individual genes or partial sequences, there is still a need to identify specific genes/genomic regions that can provide evolutionary assessments consistent with those predicted with full-length genome sequences. Here the virulent Izatnagar/94 PPRV isolate was assembled and compared to all available complete genome sequences (currently in the NCBI database) to estimate nucleotide diversity and to deduce evolutionary relationships between genes/genomic regions and the full length genomes. Our aim was to identify the preferred candidate gene for use as a phylogenetic marker, as well as to predict divergence time and explore PPRV phylogeography. Among all the PPRV genes, the H gene was identified to be the most diverse with the highest evolutionary relationship with the full genome sequences. Hence it is considered as the most preferred candidate gene for phylogenetic study with 93% identity set as a nucleotide cutoff. A whole genome nucleotide sequence cutoff value of 94% permitted specific differentiation of PPRV lineages. All the isolates examined in the study were found to have a most recent common ancestor in the late 19th or in the early 20th century with high posterior probability values. The Bayesian skyline plot revealed a decrease in genetic diversity among lineage IV isolates since the start of the vaccination program and the network analysis localized the ancestry of PPRV to Africa.