No abstract

The present study developed and standardized an enzime-linked immunosorbent assay (ELISA)

The COVID-19 pandemic caused by infection with the betacoronavirus SARS-CoV-2 is the greatest public health defiant on a global scale in the last 100 years. Governments and health Institutes face challenges during the pandemic, related to the diagnosis, mitigation, treatment, and timely detection after the epidemic peak for the prevention of new infections and the evaluation of the real impact of the COVID-19 disease in different geographic areas. To develop a valuable tool to study the seroprevalence of SARS-CoV-2 infection in Colombia, an “in-house” ELISA was achieved for the detection of IgG anti-SARS-CoV-2 antibodies in serum. The test was standardized using a antigenic epitopes “Pool” of synthetic peptide as antigen derived from antigenic regions of the spike, nucleocapsid, envelope, and membrane structural proteins, which were designed, based on the genomic information of SARS-CoV-2 circulating in Colombia. In the ELISA standardization process, 34 positive sera were used, including sera from asymptomatic and symptomatic patients (mild and severe) and 68 negative sera, including pre-pandemic historical negatives originating from patients living in arbovirus endemic areas or patients with a history of respiratory diseases and sera from patients with a negative rRT-PCR test for SARS-CoV-2. The in-house peptide ELIPSE-COL test showed promising performance, being able to detect reactivity in sera from asymptomatic and symptomatic patients. The sensitivity and specificity of the assay were 91% for both parameters. The ELIPSE-COL assay was developed as an ELISA test using synthetic peptides for the study of the seroprevalence of SARS-CoV-2 infection in Colombia.

The traditional parasitological method to diagnose taeniasis is the microscopic observation of eggs in stool samples. However, this method does not allow differentiation between Taenia saginata and Taenia solium. This aim of this study was to achieve the detection of T. solium DNA by polymerase chain reaction (PCR) and to evaluate the cross-reaction with other species of the genus Taenia and other intestinal parasites. DNA was extracted from adult T. solium cestodes by cryolysis in liquid nitrogen and with the DNA stool extraction kit from Qiagen. The detection limit of the test was evaluated by DNA dilutions in water and in stool samples. DNA was extracted from proglottids of T. saginata and T. crassiceps and from stool samples containing other intestinal parasites using ethanol treatment, alkaline lysis, and the DNA stool extraction kit. Nested PCR was used to amplify a previously described fragment of the Tso31 gene, and the PCR products were analyzed by electrophoresis in 2% agarose gels followed by staining with GelRed. The nested PCR of the Tso31 gene allowed the detection of T. solium DNA in stool samples with a detection limit of 20 pg of parasite DNA. PCR showed no cross-reaction with T. saginata, T. crassiceps, or other intestinal parasites of public health importance in Colombia.