Pathological and immunohistochemical assessment of the impact of three different strains of swine enteric coronaviruses in the intestinal barrier

Swine enteric coronaviruses, such as porcine epidemic diarrhea virus (PEDV) or transmissible gastroenteritis virus (TGEV), have risen concern for the porcine industry and research community due to the increase in their virulence, their potential recombination capacity and the emergence of new variants. This in vivo study aims to compare the impact of three different strains of swine enteric coronaviruses [(two G1b (S-INDEL) PEDV strains and a recombinant TGEV-PEDV or Swine enteric coronavirus (SeCoV)] in the intestine of 3-weeks-old infected piglets, focusing on the pathology and main components of the intestinal barrier, including the number of goblet cells, and the expression of IgA as well as FoxP3, a regulatory T cell marker. Severity of lesions was evidenced in the three infected groups and was highly correlated with the viral load in feces and the frequency of viral antigen-positive cells. Furthermore, higher cellular death together with an increase in the expression of the FoxP3 marker was detected in the duodenum and jejunum of infected animals at 3 days post-infection. Our results highlight a recruitment of FoxP3+ cells in the small intestine of infected animals which may represent a response to the tissue damage caused by viral replication and cell death. Further studies should be addressed to determine the potential role of these cells during swine enteric coronavirus infections.

Predictive factors of COVID-19 in patients with negative RT-qPCR

OBJECTIVE

To evaluate the factors associated with false negatives in RT-qPCR in patients with mild-moderate symptoms of COVID-19.

MATERIALS AND METHODS

This was a cross-sectional study that used a random sample of non-hospitalized patients from the primary care management division of the Healthcare Area of Leon (58 RT-qPCR-positive cases and 52 RT-qPCR-negative cases). Information regarding symptoms was collected and all patients were simultaneously tested using two rapid diagnostic tests - RDTs (Combined - cRDT and Differentiated - dRDT). The association between symptoms and SARS-CoV-2 infection was evaluated by non-conditional logistic regression, with estimation of Odds Ratio.

RESULTS

A total of 110 subjects were studied, 52% of whom were women (mean age: 48.2±11.0 years). There were 42.3% of negative RT-qPCRs that were positive in some RDTs. Fever over 38°C (present in 35.5% of cases) and anosmia (present in 41.8%) were the symptoms most associated with SARS-CoV-2 infection, a relationship that remained statistically significant in patients with negative RT-qPCR and some positive RDT (aOR=6.64; 95%CI=1.33-33.13 and aOR=19.38; 95% CI=3.69-101.89, respectively).

CONCLUSIONS

RT-qPCR is the technique of choice in the diagnosis of SARS-CoV-2 infection, but it is not exempt from false negatives. Our results show that patients who present mild or moderate symptoms with negative RT-qPCR, but with fever and/or anosmia, should be considered as suspicious cases and should be evaluated with other diagnostic methods.