RESUMO
The emergence and global dissemination of Severe Acute Respiratory Syndrome virus 2 (SARS-CoV-2) variants of concern (VOCs) have been described as the main factor driving the Coronavirus Disease 2019 pandemic. In Brazil, the Gamma variant dominated the epidemiological scenario during the first period of 2021. Many Brazilian regions detected the Delta variant after its first description and documented its spread. To monitor the introduction and spread of VOC Delta, we performed Polymerase Chain Reaction (PCR) genotyping and genome sequencing in ten regional sentinel units from June to October 2021 in the State of Minas Gerais (MG). We documented the introduction and spread of Delta, comprising 70 per cent of the cases 8 weeks later. Comparing the viral loads of the Gamma and Delta dominance periods, we provide additional evidence that the latter is more transmissible. The spread and dominance of Delta did not culminate in the increase in cases and deaths, suggesting that the vaccination may have restrained the epidemic growth. Analysis of 224 novel Delta genomes revealed that Rio de Janeiro state was the primary source for disseminating this variant in the state of MG. We present the establishment of Delta, providing evidence of its enhanced transmissibility and showing that this variant shift did not aggravate the epidemiological scenario in a high immunity setting.
RESUMO
The laboratory diagnosis of visceral leishmaniasis (VL) presents limitations related to its sensibility and/or specificity. In this context, the aim of this study was to evaluate an enzyme-linked immunoassay to detect IgG antibodies against Leishmania infantum exo-antigens for diagnosis of VL, called ELISA-Exo. This assay was applied in 309 masked serum samples from VL, tegumentary leishmaniasis, Chagas disease, schistosomiasis mansoni, malaria patients, and healthy individuals. The results were compared with those from ELISA using rK39 as antigen (ELISA-rK39). The ELISA assays presented sensitivity of 96.8% and 98.4% (p = 0.68), specificity of 92.4% for both, and diagnostic accuracy of 94.2% and 94.8% (p = 0.48) by the ELISA-Exo and ELISA-rK39, respectively. An excellent agreement beyond chance (Kappa index = 0.82) was obtained when the results from ELISA assays were cross-tabulated. The Western blotting showed that false-positive results presented by ELISA-Exo probably were produced by cross-reactivity of antigens shared with the species of the family Trypanosomatidae. In the future, an immunoproteomic approach can contribute for identification of main immunoreactive L. infantum exo-antigens.
