Point-of-care testing for COVID-19: a simple two-step molecular diagnostic development and validation during the SARS-CoV-2 pandemic.

BACKGROUND: During the coronavirus disease 19 (COVID-19) pandemic, diagnostic testing of the general population proved challenging due to limitations of the gold-standard diagnostic procedure using reverse transcription real-time polymerase chain reaction (RT-qPCR) for large-scale testing on the centralised model, especially in low-resource areas. OBJECTIVES: To address this, a point-of-care (PoC) diagnostic protocol for COVID-19 was developed, providing fast, reliable, and affordable testing, particularly for low-mid develop areas. METHODS: The PoC diagnostic process combines a simple paper-based RNA extraction method housed within a 3D-printed plastic device with a colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay. Nasopharyngeal/oropharyngeal swabs (NOS) and saliva samples were tested between 2020 and 2021, with the assistance of Santa Catarina's State Health Secretary, Brazil. FINDINGS: The developed diagnostic protocol showed a limit of detection of 9,900 copies and an overall diagnostic specificity of 98% for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from 1,348 clinical analysed samples. The diagnostic sensitivity was 95% for NOS samples, 85% for early morning saliva, and 69% for indiscriminate saliva. MAIN CONCLUSIONS: In conclusion, the developed device successfully extracted SARS-CoV-2 viral RNA from swabs and saliva clinical samples. When combined with colorimetric RT-LAMP, it provides results within 45 min using minimal resources, thus delivering a diagnostic kit protocol that is applicable in large-scale sampling.

Therapeutic effects of vaccine derived from amastigote surface protein-2 (ASP-2) against Chagas disease in mouse liver.

This study investigated the efficacy of the vaccine in liver of mice infected with the Trypanosoma cruzi (T. cruzi) and immunized with AdASP-2. For this purpose, histopathological analysis and gene expression of COX-2, TNF-alpha, TNFR, iNOS, cytochrome C, caspase-3, TLR4, IL-6 and IL10 were evaluated. The following groups were used in this study: Group 1 - Control Group (CTRL) animals received AdßGal vehicle; Group 2 - Infected Group (TC) animals were infected with T. cruzi; Group 3 - Immunized Group (AdASP-2): animals were immunized by AdASP-2 vaccine; Group 4 - Immunized and Infected Group (AdASP-2+TC) animals were infected with T. cruzi and immunized by AdSP-2 vaccine. A significant decrease of amastigote nests was noticed in the group of animals that were immunized with AdASP-2 and infected on the same day. COX-2 and TNF-alpha gene expressions increased in TC group, whereas TNF-alpha decreased in the TC+AdASP-2 group. TNFR expression was high in AdASP-2+TC group. iNOS expression was high for all experimental groups whereas cytochrome C decreased for all experimental groups. Caspase 3 increased in TC and TC+AdASP-2 groups. The gene expression of TLR4 and IL-10 showed an increase in AdASP-2+TC group. Finally, hepatic fibrosis was noticed to TC and AdASP-2 + TC groups. Taken together, our results demonstrated that vaccination with AdASP-2 was effective against the acute phase of experimental Chagas disease as a result of a more powerful and rapid immune response closely related to expression of some inflammatory genes, such as iNOS, TNF-alpha, TLR 4, and IL-10.

Prophylactic effect of physical exercise on Aß1-40-induced depressive-like behavior and gut dysfunction in mice.

Alzheimer's disease (AD) is a prevalent neurodegenerative disease that is highly comorbid with depression. Gut dysfunction has been proposed as a possible risk factor for both clinical conditions. In the present study, we investigated the ability of treadmill exercise for 4 weeks (5 days/week, 40 min/day) to counteract amyloid ß1-40 peptide (Aß1-40)-induced depressive-like behavior, alterations in morphological parameters of the duodenum, and the abundance of Firmicutes and Bacteroidetes phyla. Aß1-40 administration (400 pmol/mouse, i.c.v.) increased immobility time in the tail suspension test (TST) and reduced time spent sniffing in the female urine sniffing test (FUST), indicating behavioral despair and impairment in reward-seeking behavior. These behavioral alterations, indicative of depressive-like behavior, were accompanied by reduced villus width in the duodenum. Moreover, photomicrographs obtained by transmission electron microscopy revealed abnormal epithelial microvilli in the duodenum from sedentary Aß1-40-exposed mice, characterized by shorter microvilli and heterogeneity in the length of these structures that exhibit a disordered packing. Regarding the ultrastructure of Paneth cells, Aß1-40 administration caused a reduction in the secretory granule diameter, as well as an enlarged peripheral halo. These animals also presented reduced Firmicutes and increased Bacteroidetes abundance, and increased Bacteroidetes/Firmicutes ratio. Most of the alterations observed in Aß1-40-exposed mice were prevented by the practice of physical exercise. Altogether the results provide evidence of the prophylactic effect of physical exercise on Aß1-40-induced depressive-like behavior and gut dysfunction in mice, suggesting that physical exercise could be useful for preventing depression associated with AD.