The Brazilian Cerrado fauna shows very wide diversity and can be a potential viral reservoir. Therefore, the animal’s susceptibility to some virus can serve as early warning signs of potential human virus diseases. Moreover, the wild animal virome of this biome is unknown. Based on this scenario, high-throughput sequencing contributes a robust tool for the identification of known and unknown virus species in this environment. In the present study, faeces samples from cerrado birds (Psittacara leucophthalmus, Amazona aestiva, and Sicalis flaveola) and mammals (Didelphis albiventris, Sapajus libidinosus, and Galictis cuja) were collected at the Veterinary Hospital, University of Brasília. Viral nucleic acid was extracted, submitted to random amplification, and sequenced by Illumina HiSeq platform. The reads were de novo assembled, and the identities of the contigs were evaluated by Blastn and tblastx searches. Most viral contigs analyzed were closely related to bacteriophages. Novel archaeal viruses of the Smacoviridae family were detected. Moreover, sequences of members of Adenoviridae, Anelloviridae, Circoviridae, Caliciviridae, and Parvoviridae families were identified. Complete and nearly complete genomes of known anelloviruses, circoviruses, and parvoviruses were obtained, as well as putative novel species. We demonstrate that the metagenomics approach applied in this work was effective for identification of known and putative new viruses in faeces samples from Brazilian Cerrado fauna.

A non-transgenic approach based on RNA interference was employed to induce protection against tomato mosaic virus (ToMV) infection in tomato plants. dsRNA molecules targeting the cp gene of ToMV were topically applied on plants prior to virus inoculation. Protection was dose-dependent and sequence-specific. While no protection was achieved when 0–16 µg dsRNA were used, maximum rates of resistance (60 and 63%) were observed in doses of 200 and 400 µg/plant, respectively. Similar rates were also obtained against potato virus Y when targeting its cp gene. The protection was quickly activated upon dsRNA application and lasted for up to 4 days. In contrast, no detectable antiviral response was triggered by the dsRNA from a begomovirus genome, suggesting the method is not effective against phloem-limited DNA viruses. Deep sequencing was performed to analyze the biogenesis of siRNA populations. Although long-dsRNA remained in the treated leaves for at least 10 days, its systemic movement was not observed. Conversely, dsRNA-derived siRNA populations (mainly 21- and 22-nt) were detected in non-treated leaves, which indicates endogenous processing and transport through the plant. Altogether, this study provides critical information for the development of novel tools against plant viruses; strengths and limitations inherent to the systems are discussed.

Orthotospoviruses (genus Orthotospovirus, family Tospoviridae) are amongst the most devastating plant viruses worldwide, causing severe damage to many economically important vegetable crops, such as tomato and sweet pepper. Monitoring virus populations is an important step for estimating virus damage and epidemiology, and gaining insights into the adaptation processes undergone by orthotospoviruses. Here, we studied the orthotospovirus populations infecting vegetable crops in Brazil and the Dominican Republic, including species diversity, genome comparison and phylogenetic analyses. Comparisons of virus populations showed that in Brazil, which is considered a center of orthotospovirus diversity, groundnut rinspot virus (GRSV) is prevalent, infecting 41% of the plants, whereas tomato spotted wilt virus (TSWV) and tomato chlorotic spot virus (TCSV) were present in 4% and 9% of the samples, respectively. In the Dominican Republic, which can be considered an environment with low orthotospovirus diversity, 55% of the samples were infected with TSWV, 11% showed TCSV infection and no GRSV was detected. The occurrence of mixed infection was low in Brazil, at only 5%, but no mixed infection was detected in the Dominican Republic. The low rates of mixed infections may prevent the emergence of genomes resulting from reassortment. Indeed, no reassortant viruses were detected in either country, except for TCSV, recently proposed as representing a reassortant orthotospovirus species.

Apple stem grooving virus (ASGV, genus Capillovirus) is disseminated worldwide, usually causing a latent infection in most commercial apple cultivars. However, infected scions grafted onto sensitive material display reduction of yield, loss of fruit quality and tree decline. In Brazil ASGV is associated with severe phloem necrosis, xylem pitting and decline of apple trees on Maruba-kaido (Malus prunifolia cv. Ringo) rootstocks usually in a complex with other latent viruses. Two Brazilian ASGV isolates from a mixed infection causing differing reactions on apple cv. Fuji on Maruba-kaido rootstocks, i.e., normal growth vs. tree decline, have been completely sequenced. The differing intensity of symptoms they co-induced on several woody indicator species/cultivars are indicative of biological differences between the two inocula. Their nucleotide sequences are 92.2% identical and display between 79.2% and 97.1% identity with other ASGV isolates available in GenBank. The two isolates (M219-3 and M220) shared 92.3% deduced amino acid (daa) sequence identity for ORF1, 95.3% for ORF2 and 93.3% for the CP gene. A high degree of daa identity, 95.8% and 96.6%, was observed between the CPs of M219-3 and M220, respectively, with the Brazilian isolate UV01. Potential recombination events and phylogenetic relationships to major parents were investigated in isolates M219-3 and M220.

No abstract