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 / Factores predictivos del COVID-19 en pacientes con RT-qPCR negativa

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

OBJETIVO: Evaluar los factores asociados con falsos negativos a RT-qPCR negativa y sintomatología leve o moderada de COVID-19. MATERIALES Y MÉTODOS: Estudio transversal. Se utilizó una muestra aleatoria de pacientes no hospitalizados de la Gerencia de Atención Primaria del Área de Salud de León (58 con RT-qPCR positiva y 52 con RT-qPCR negativa). Se recogió información sobre síntomas, y a todos se les realizaron simultáneamente dos pruebas de diagnóstico rápido (PDR): combinada (PRD-C) y diferenciada (PRD-D). La asociación de los síntomas con la infección por SARS-CoV-2 se evaluó mediante regresión logística no condicional, con el cálculo de odds ratio (OR). RESULTADOS: Se estudiaron un total de 110 personas, y el 52% de ellas fueron mujeres (edad media: 48,2±11,0años). El 42,3% de las RT-qPCR negativas dieron positivo en algún PDR. La fiebre de más de 38°C (presente en el 35,5% de los casos) y la anosmia (presente en el 41,2%) fueron los síntomas más asociados a la infección por SARS-CoV-2, relación que se mantuvo estadísticamente significativa en pacientes con RT-qPCR negativa y algún PDR positivo (ORa: 6,64; IC95%: 1,33-33,13, y ORa: 19,38; IC95%: 3,69-101,89, respectivamente). CONCLUSIONES: La RT-qPCR es la técnica de elección en el diagnóstico de la infección por SARS-CoV-2, pero no está exenta de falsos negativos. Nuestros resultados ponen de manifiesto que los pacientes que presentan síntomas leves o moderados con RT-qPCR negativa pero con fiebre y/o anosmia deben ser considerados casos sospechosos y deben ser valorados con otros métodos diagnósticos

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.