BackgroundSince the discovery of giant viruses infecting amoebae in 2003, many dogmas of virology have been revised and the search for these viruses has been intensified. Over the last few years, several new groups of these viruses have been discovered in various types of samples and environments.In this work, we describe the isolation of 68 giant viruses of amoeba obtained from environmental samples from Brazil and Antarctica.MethodsIsolated viruses were identified by hemacolor staining, PCR assays and electron microscopy (scanning and/or transmission).ResultsA total of 64 viruses belonging to the Mimiviridae family were isolated (26 from lineage A, 13 from lineage B, 2 from lineage C and 23 from unidentified lineages) from different types of samples, including marine water from Antarctica, thus being the first mimiviruses isolated in this extreme environment to date. Furthermore, a marseillevirus was isolated from sewage samples along with two pandoraviruses and a cedratvirus (the third to be isolated in the world so far).ConclusionsConsidering the different type of samples, we found a higher number of viral groups in sewage samples. Our results reinforce the importance of prospective studies in different environmental samples, therefore improving our comprehension about the circulation anddiversity of these viruses in nature.Electronic supplementary materialThe online version of this article (doi: 10.1186/s12985-018-0930-x) contains supplementary material, which is available to authorized users.

As the depth increases and the light fades in oceanic cold seeps, a variety of chemosynthetic-based benthic communities arise. Previous assessments reported polychaete annelids belonging to the family Siboglinidae as part of the fauna at cold seeps, with the 'Vestimentifera' clade containing specialists that depend on microbial chemosynthetic endosymbionts for nutrition. Little information exists concerning the microbiota of the external portion of the vestimentiferan trunk wall. We employed 16S rDNA-based metabarcoding to describe the external microbiota of the chitin tubes from the vestimentiferan Escarpia collected from a chemosynthetic community in a cold seep area at the southwestern Atlantic Ocean. The most abundant operational taxonomic unit (OTU) belonged to the family Pirellulaceae (phylum Planctomycetes), and the second most abundant OTU belonged to the order Methylococcales (phylum Proteobacteria), composing an average of 21.1 and 15.4% of the total reads on tubes, respectively. These frequencies contrasted with those from the surrounding environment (sediment and water), where they represent no more than 0.1% of the total reads each. Moreover, some taxa with lower abundances were detected only in Escarpia tube walls. These data constitute on the first report of an epibiont microbial community found in close association with external surface of a cold-seep metazoan, Escarpia sp., from a chemosynthetic community in the southwestern Atlantic Ocean.

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During the 2009 influenza A pH1N1 pandemics in Brazil, the state that was most affected was Rio Grande do Sul (RS), with over 3,000 confirmed cases, including 298 deaths. While no cases were confirmed in 2010, 103 infections with 14 deaths by pH1N1 were reported in 2011. Genomic analysis of the circulating viruses is fundamental for understanding viral evolution and supporting vaccine development against these pathogens. This study investigated whole genomes of six pH1N1 virus isolates from pandemic and post-pandemic periods in RS, Brazil. Phylogenetic analysis using the concatenated genome segments demonstrated that at least two lineages of the virus co-circulated in RS during the 2009 pandemic period. Moreover, our analysis showed that the post-pandemic pH1N1 virus from 2011 constitutes a distinct clade whose ancestor belongs to clade 7. All six isolates contained amino acid substitutions in their proteins when compared to the archetype strains California/04/2009 and California/07/2009. The 2011 isolates contained more amino acid substitutions, and most of their genes were under purifying selection. Based on the amino acid substitutions in HA epitopes from strains isolated in RS, Brazil, in silico analysis predicted a decrease in vaccine efficacy against post-pandemic strains (median 31.562 %) in relation to pandemic ones (median 39.735 %).