Dengue virus serotype 2 genotype III evolution during the 2019 outbreak in Mato Grosso, Midwestern Brazil.

DENV-2 was the main responsible for a 70% increase in dengue incidence in Brazil during 2019. That year, our metagenomic study by Illumina NextSeq on serum samples from acute febrile patients (n = 92) with suspected arbovirus infection, sampled in 22 cities of the state of Mato Grosso (MT), in the middle west of Brazil, revealed eight complete genomes and two near-complete sequences of DENV-2 genotype III, one Human parvovirus B19 genotype I (5,391 nt) and one Coxsackievirus A6 lineage D (4,514 nt). These DENV-2 sequences share the aminoacidic identities of BR4 lineage on E protein domains I, II and III, and were included in a clade with sequences of the same lineage circulating in the southeast of Brazil in the same year. Nevertheless, 11/34 non-synonymous mutations are unique to three strains inthis study, distributed in the E (n = 6), NS3 (n = 2) and NS5 (n = 3) proteins. Other 14 aa changes on C (n = 1), E (n = 3), NS1 (n = 2), NS2A (n = 1) and NS5 (n = 7) were first reported in a genotype III lineage, having been already reported only in other DENV-2 genotypes. All 10 sequences have mutations in the NS5 protein (14 different aa changes). Nine E protein aa changes found in two sequences, six of which are unique, are in the ectodomain; where the E:M272T change is on the hinge of the E protein at domain II, in a region critical for the anchoring to the host cell receptor. The NS5:G81R mutation, in the methyltransferase domain, was found in one strain of this study. Altogether, these data points to an important evolution of DENV-2 genotype III lineage BR4 during this outbreak in 2019 in MT. Genomic surveillance is essential to detect virus etiology and evolution, possibly related to immune evasion and viral fitness changes leading to future novel outbreaks.

30th Brazilian Society for Virology 2019 Annual Meeting-Cuiabá, Mato Grosso, Brazil.

The 30th meeting of the Brazilian Society for Virology (SBV) was held, for the first time in its 30 years of existence, in Cuiabá, the capital of Mato Grosso State, Central Western Brazil, a tropical region between the three richest biomes in the world: Amazon Florest, Cerrado and Pantanal. In recent years, the field of virology has been built in the State. The aim of this report is to support participants and virologists to receive the most up-to-date information about the meeting, which occurred from 16 to 19 October 2019. National and international speakers gave SBV the opportunity to learn about their experience on their virology fields, sharing recent scientific findings, compiling conferences, round table presentations and work presentations in oral and poster sessions. The meeting held over 300 attendants, who were also involved on oral and poster presentations, showing a great variety of recent unpublished studies on environmental, basic, animal, human, plant and invertebrate virology. In addition, SBV offered the Helio Gelli Pereira award for the best research studies in each field presented during the meeting. The 30th meeting of SBV was very productive and has also encouraged scientific partnership and collaboration among virologists worldwide.

SAINT LOUIS ENCEPHALITIS VIRUS IN MATO GROSSO, CENTRAL-WESTERN BRAZIL.

The dengue virus (DENV), which is frequently involved in large epidemics, and the yellow fever virus (YFV), which is responsible for sporadic sylvatic outbreaks, are considered the most important flaviviruses circulating in Brazil. Because of that, laboratorial diagnosis of acute undifferentiated febrile illness during epidemic periods is frequently directed towards these viruses, which may eventually hinder the detection of other circulating flaviviruses, including the Saint Louis encephalitis virus (SLEV), which is widely dispersed across the Americas. The aim of this study was to conduct a molecular investigation of 11 flaviviruses using 604 serum samples obtained from patients during a large dengue fever outbreak in the state of Mato Grosso (MT) between 2011 and 2012. Simultaneously, 3,433 female Culex spp. collected with Nasci aspirators in the city of Cuiabá, MT, in 2013, and allocated to 409 pools containing 1-10 mosquitoes, were also tested by multiplex semi-nested reverse transcription PCR for the same flaviviruses. SLEV was detected in three patients co-infected with DENV-4 from the cities of Cuiabá and Várzea Grande. One of them was a triple co-infection with DENV-1. None of them mentioned recent travel or access to sylvatic/rural regions, indicating that transmission might have occurred within the metropolitan area. Regarding mosquito samples, one pool containing one Culex quinquefasciatus female was positive for SLEV, with a minimum infection rate (MIR) of 0.29 per 1000 specimens of this species. Phylogenetic analysis indicates both human and mosquito SLEV cluster, with isolates from genotype V-A obtained from animals in the Amazon region, in the state of Pará. This is the first report of SLEV molecular identification in MT.