Padronização de técnicas moleculares e detecção de west nile virus em pacientes sintomáticos no estado do piauí

Abstract

Arboviruses are composed of hundreds of viruses transmitted by arthropod vectors. These viruses cause major public health concern worldwide, particularly in tropical and subtropical areas, where many of them are responsible for a high morbidity and mortality rate. West Nile virus (WNV) is an arbovirus of great clinical importance because it causes West Nile fever. Although most cases of WNV are asymptomatic, this virus may be capable of causing serious diseases in humans, such as encephalitis, and may lead to death. Piauí is a Brazilian state with favorable weather conditions for the spread of several arboviruses, presenting the only four cases for WNV in Brazil. Many cases of WNV are suspected to be underestimated and misdiagnosed because their initial manifestations are very similar to other arboviruses and because they are cross-reactive with phylogenetically related viruses, making it difficult to differentiate by serological tests. For this reason, this study aimed to investigate, through molecular methods, the possible circulation of West Nile virus during the years 2016-2019 in the State of Piauí. Primers were constructed to amplify the E gene, as well as standardize TR-PCR assays to amplify the WNV C / prM and E regions. Concomitantly with the standards were collected and selected 106 samples with symptoms for arbovirus, with a viremia period between 2-7 days and which were negative for other arboviruses by molecular techniques. The tests with the samples did not show viral genome amplification, however this does not indicate that this virus is not circulating, considering the detected cases in the state. One of the reasons that may contribute to the low detection of this virus is the cross immunity caused by other flaviviruses. The present study also succeeded in standardizing the qPCR technique for WNV RTU amplification, in order to broaden and improve the detection capacity of this virus, and it was possible to quantify the viral cDNA in the samples, correlating with the progression of atypical symptoms and forms. infection. Further studies based on the differential diagnosis of arboviruses should be continued, as they will inform the actual number of cases of these viruses, thus helping epidemiological surveillance to take appropriate vector control measures to prevent possible outbreaks and epidemics in the Piaui population.