Human enteric adenovirus species F (HAdV-F) is one of the most common pathogens responsible for acute gastroenteritis worldwide. Brazil is a country with continental dimensions where continuous multiregional surveillance is vital to establish a more complete picture of the epidemiology of HAdV-F. The aim of the current study was to investigate the molecular epidemiology of HAdV-F using full-genome data in rural and low-income urban areas in northern Brazil. This will allow a genetic comparison between Brazilian and global HAdV-F strains. The frequency of HAdV-F infections in patients with gastroenteritis and molecular typing of positive samples within this period was also analysed. A total of 251 stool samples collected between 2010 and 2016 from patients with acute gastroenteritis were screened for HAdV-F using next-generation sequencing techniques. HAdV-F infection was detected in 57.8 % (145/251) of samples. A total of 137 positive samples belonged to HAdV-F41 and 7 to HAdV-F40. HAdV-F40/41 dual infection was found in one sample. Detection rates did not vary significantly according to the year. Single HAdV-F infections were detected in 21.9 % (55/251) of samples and mixed infections in 37.4 % (94/251), with RVA/HAdV-F being the most frequent association (21.5 %; 54/251). Genetic analysis indicated that the HAdV-F strains circulating in Brazil were closely related to worldwide strains, and the existence of some temporal order was not observed. This is the first large-scale HAdV-F study in Brazil in which whole-genome data and DNA sequence analyses were used to characterize HAdV-F strains. Expanding the viral genome database could improve overall genotyping success and assist the National Center for Biotechnology Information (NCBI)/GenBank in standardizing the HAdV genome records by providing a large set of annotated HAdV-F genomes.

Plasma from patients with dengue-like symptoms was collected in 2013 to 2016 from the Brazilian states of Tocantins and Amapa. 781 samples testing negative for IgM against Dengue, Zika, and Chikungunya viruses and for flaviviruses, alphaviruses and enteroviruses RNA using RT-PCRs were analyzed using viral metagenomics. Viral particles-associated nucleic acids were enriched, randomly amplified, and deep sequenced in 102 mini-pools generating over 2 billion reads. Sequence data was analyzed for the presence of known and novel eukaryotic viral reads. Anelloviruses were detected in 80%, human pegivirus 1 in 19%, and parvovirus B19 in 17% of plasma pools. HIV and enteroviruses were detected in two pools each. Previously uncharacterized viral genomes were also identified, and their presence in single plasma samples confirmed by PCR. Chapparvovirus and ambidensovirus genomes, both in the Parvoviridae family, were partially characterized showing 33% and 34% identity in their NS1 sequences to their closest relative. Molecular surveillance using pre-existing plasma from febrile patients provides a readily scalable approach for the detection of novel, potentially emerging, viruses.

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Diarrhea remains one of the most common causes of deaths in children. Although many studies have investigated the prevalence of enteric pathogens around the globe some diarrheal episodes remain unexplained. It is possible that some yet-unidentified viral agents could be related to these cases of gastroenteritis. By using viral metagenomics techniques, we screened 251 fecal samples of children between 0.5 to 2.5-year-old with acute diarrhea not associated with common pathogens. These children live in rural areas and have different levels of contact with animals such as pigs, cows and bats. Here we report a complete genome of one mammalian orthoreovirus (MRV) type 3, denoted TO-151/BR, detected in a female child in the state of Tocantins (north of Brazil). Brazilian TO-151/BR strain was classified as MRV-3 based on S1 phylogeny and was closely related to porcine Asian strains. Phylogenetic analyses showed that other segments were more similar to MRV-3s of different geographic locations and hosts, including human and bats, highlighting genome reassortment and lack of host-specific barriers. This is the first report of MRV-3 in South America and a hypothesis of a silent long-term circulation of this virus in Brazil has been raised.