The screening of flu-like syndrome is difficult due to nonspecific symptoms or even oligosymptomatic presentation and became even more complex during the Covid-19 pandemic. However, an efficient screening tool plays an important role in the control of highly contagious diseases, allowing more efficient medical-epidemiological approaches and rational management of global health resources. Infrared thermography is a technique sensitive to small alterations in the skin temperature which may be related to early signs of inflammation and thus being relevant in the detection of infectious diseases. Thus, the objective of this study was to evaluate the potential of facial thermal profiles as a risk evaluator of symptoms and signs of SARs diseases, using COVID-19 as background disease. A total of 136 patients were inquired about the most common symptoms of COVID-19 infection and were submitted to an infrared image scanning, where the temperatures of 10 parameters from different regions of the face were captured. We used RT-qPCR as the ground truth to compare with the thermal parameters, in order to evaluate the performance of infrared imaging in COVID-19 screening. Only 16% of infected patients had fever at the hospital admission, and most infrared thermal variables presented values of temperature significantly higher in infected patients. The maximum eye temperature (MaxE) showed the highest predictive value at a cut-off of >35.9°C (sn = 71.87%, sp = 86.11%, LR+ = 5.18, LR- = 0.33, AUC = 0.850, p < 0.001). Our predictive model reached an accuracy of 86% for disease detection, indicating that facial infrared thermal scanning, based on the combination of different facial regions and the thermal profile of the face, has potential to act as a more accurate diagnostic support method for early COVID-19 screening, when compared to classical infrared methods, based on a single spot with the maximum skin temperature of the face.
Lyssavirus rabies (RABV) is an RNA virus and, therefore, is subject to mutations due to low RNA polymerase replication fidelity, forming a population structure known as a viral quasispecies, which is the core of RNA viruses’ adaptive strategy. Under new microenvironmental conditions, the fittest populations are selected, and the study of this process on the molecular level can help determine molecular signatures related to virulence. Our aim was to survey gene signatures on nucleoprotein and glycoprotein genes that might be involved in virulence modulation during the in vitro evolution of RABV lineages after serial passages in a neuronal cell system with or without the presence of neutralizing antibodies based on replicative fitness, in vivo neurotropism and protein structure and dynamics. The experiments revealed that amino acids at positions 186 and 188 of the glycoprotein are virulence factors of Lyssavirus rabies, and site 186 specifically might allow the attachment to heparan as a secondary cell receptor, while polymorphism at position 333 might allow the selection of escape mutants under suboptimal neutralizing antibodies titers.
The control of vampire bat rabies (VBR) in Brazil is based on the culling of Desmodus rotundus and the surveillance of outbreaks caused by D. rotundus in cattle and humans in addition to vaccination of susceptible livestock. The detection of anti-rabies antibodies in vampire bats indicates exposure to the rabies virus, and several studies have reported an increase of these antibodies following experimental infection. However, the dynamics of anti-rabies antibodies in natural populations of D. rotundus remains poorly understood. In this study, we took advantage of recent outbreaks of VBR among livestock in the Sao Paulo region of Brazil to test whether seroprevalence in D. rotundus reflects the incidence of rabies in nearby livestock populations. Sixty-four D. rotundus were captured during and after outbreaks from roost located in municipalities belonging to three regions with different incidences of rabies in herbivores. Sixteen seropositive bats were then kept in captivity for up to 120 days, and their antibodies and virus levels were quantified at different time points using the rapid fluorescent focus inhibition test (RFFIT). Antibody titers were associated with the occurrence of ongoing outbreak, with a higher proportion of bats showing titer >0.5 IU/ml in the region with a recent outbreak. However, low titers were still detected in bats from regions reporting the last outbreak of rabies at least 3 years prior to sampling. This study suggests that serological surveillance of rabies in vampire bats can be used as a tool to evaluate risk of outbreaks in at risk populations of cattle and human.
Our results indicate the possible occurrence of a recent peak in infection by the rabies virus in these bat populations, which represents an important alert, given that attacks by hematophagous bats are a constant threat in the study area, contributing to the probability of the occurrence of new cases of rabies.
A raiva é uma encefalite viral aguda e quase sempre fatal, tem distribuição global e causa cerca de 59 mil mortes/ano, principalmente em crianças de países em desenvolvimento. Provocada pelo Lyssavirus rabies (RABV) -vírus de genoma RNA, formado por cinco genes (N, P, M, G e L), é um dos mais antigos patógenos já descritos pela humanidade, capaz de acometer todos os mamíferos, mas mantém os morcegos (Chiroptera) como hospedeiro reservatório. Os quirópteros são os únicos mamíferos com capacidade para voar, o que os possibilita percorrer grandes distâncias e facilita a disseminação de vírus, como o RABV. Com o intuito de comparar a taxonomia morfológica e molecular de quirópteros, foi realizado o sequenciamento parcial do gene COI de 384 indivíduos, utilizando o SNC de diversas espécies do Estado de São Paulo. Todas as sequências foram depositadas e se encontram disponíveis no banco de dados GenBank (NCBI). A identificação genética das espécies pelo gene COI (DNA barcoding) foi resultado do sistema BOLD de identificação, as relações filogenéticas entre os indivíduos foram avaliadas com a elaboração de árvores de Máxima Verossimilhança e com análise dos parâmetros de diversidade genética (número de haplótipos, número de sítios variáveis, diversidade haplotípica e nucleotídica), além da construção das redes de haplótipos, incluindo sequências do gene COI disponíveis em banco de dados. Durante o estudo, foram encontrados indivíduos com sequências do gene COI idênticas, separados por mais de 3mil km de distância geográfica. Diferenças significativas entre a taxonomia morfológica e molecular do gênero Myotis foram destacadas, evidenciando anecessidade do uso de marcadores moleculares na identificação de espécies, principalmente as mais complexas. Em paralelo, o viés de uso de códons foi avaliado no genoma completo de RABV, utilizando 51 sequências de isolados já disponíveis em banco de dados. O mRNA da β-actina foi eleito para gerar 43 sequências parciais de quirópteros e utilizá-las como conjunto de referência de genes altamente expressos, empregados na análise dos indicadores de uso de códons, além de gerar a filogenia baseada em β-actina. Índices como conteúdo GC, RSCU, Enc, CAI e RCDI foram calculados, a fim de avaliar o viés de uso e inferir a força evolutiva que o influencia, apesar de RABV apresentar baixo viés de utilização. Valores de RSCU foram convertidos em dados binários e possibilitaram gerar cinco árvores de Neighbor-Joining. Um ensaio in vivo foi realizado em camundongos inoculados com amostra de quiróptero positivo para raiva, com finalidade de comparar a carga viral na mudança de hospedeiros e verificar suas implicações no uso de códons. De maneira geral, RABV mostrou-se um vírus de baixo viés de uso de códons, preferindo utilizar os terminados em A/T, além de indicar que o viés é influenciado pela seleção natural. Os padrões de uso de códons são diretamente influenciados pela coevolução entre vírus e hospedeiros.
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