Oropouche virus (OROV) is the causative agent of Oropouche fever, an urban febrile arboviral disease widespread in South America, with >30 epidemics reported in Brazil and other Latin American countries during 1960–2009. To describe the molecular epidemiology of OROV, we analyzed the entire N gene sequences (small RNA) of 66 strains and 35 partial Gn (medium RNA) and large RNA gene sequences. Distinct patterns of OROV strain clustered according to N, Gn, and large gene sequences, which suggests that each RNA segment had a different evolutionary history and that the classification in genotypes must consider the genetic information for all genetic segments. Finally, time-scale analysis based on the N gene showed that OROV emerged in Brazil ≈223 years ago and that genotype I (based on N gene data) was responsible for the emergence of all other genotypes and for virus dispersal.

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Saint Louis encephalitis virus (SLEV), a member of the genus Flavivirus (family Flaviviridae), is an encephalitogenic arbovirus broadly distributed in the Americas. Phylogenetic analysis based on the full-length E gene sequences obtained for 30 Brazilian SLEV strains was performed using different methods including Bayesian and relaxed molecular clock approaches. A new genetic lineage was suggested, hereafter named genotype VIII, which co-circulates with the previously described genotype V in the Brazilian Amazon region. Genotypes II and III were restricted to Sã o Paulo state (South-east Atlantic rainforest ecosystem). The analysis also suggested the emergence of an SLEV common ancestor between 1875 and 1973 (mean of 107 years ago), giving rise to two major genetic groups: genotype II, more prevalent in the North America, and a second group comprising the other genotypes (I and III-VIII), broadly dispersed throughout the Americas, suggesting that SLEV initially emerged in South America and spread to North America.In conclusion, the current study demonstrates the high genetic variability of SLEV and its geographical dispersion in Brazil and other New World countries. INTRODUCTIONSaint Louis encephalitis virus (SLEV) is an encephalitogenic arbovirus with a primary life cycle associated with Culex mosquitoes and wild birds (Travassos da Rosa et al., 1997; Vasconcelos et al., 1998;Reisen, 2003). Taxonomically, Saint Louis encephalitis virus is a recognized species of the genus Flavivirus, family Flaviviridae, and belongs to the Japanese encephalitis virus (JEV) group, which includes other important human pathogens such as West Nile virus (WNV), JEV and Murray Valley encephalitis virus (Calisher & Gould, 2003).SLEV is widely distributed throughout the western hemisphere from Canada to Argentina. SLEV was first isolated in 1933 during a major epidemic that occurred in St Louis, Missouri, USA, with more than 1000 encephalitis cases reported. Outbreaks or clusters of encephalitis cases associated with SLEV have been reported annually in the USA (Reisen, 2003). Usually, the fatality rate ranges from 5 to 20 % (Tsai & Mitchell, 1988), with higher mortality rates observed among the elderly (.75 years of age) (Reisen, 2003).The low number of human cases reported in tropical regions of the Americas may reflect inadequate laboratory diagnosis, circulation of less virulent virus strains and/or enzootic cycles involving mosquitoes that are not typically anthropophilic (Spense, 1980). Only three SLEV strains have been isolated from humans in Brazil. Two patients resident in Para state had clinical manifestations characterized by fever and jaundice (Pinheiro et al., 1981; Vasconcelos et al., 1998), whilst one from São Paulo was suspected of dengue-like disease (Rocco et al., 2005). None of them had neurological symptoms. Recently, the SLEV genome was detected by RT-PCR in four patients with clinical symptoms similar to those observed in dengue fever, as well as in two other patients clinically diagnosed as presenting with viral...

Dengue is the most important arbovirus disease in tropical and sub-tropical countries, and can be caused by infection with any of the four-dengue virus (DENV) serotypes. Infection with DENV can lead to a broad clinical spectrum, ranging from sub-clinical infection or an influenza-like disease known as dengue fever (DF) to a severe, sometimes fatal, disease characterized by hemorrhage and plasma leakage that can lead to shock, known as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). The diagnosis of dengue is routinely accomplished by serologic assays, such as IgM and IgG ELISAs, as well as HI tests, analyzing serum samples obtained from patients with at least 7 days of symptoms onset. These tests cannot be used for diagnosis during the early symptomatic phase. In addition, antibodies against dengue are broad reactive with other flaviviruses. Therefore, a specific diagnostic method for acute DENV infection is of great interest. In that sense, the real-time RT-PCR has become an important tool that can be used for early and specific detection of dengue virus genome in human serum samples. This study describes a simple, specific, and sensitive real-time RT-PCR for early diagnosis of dengue virus infection.