RESUMEN
Cross-neutralizing activity of human antibody response against Dengue virus complex (DENV) changes importantly over time. Domain III (DIII) of the envelope protein of DENV elicits a potently neutralizing and mostly type-specific IgG response. We used sera from 24 individuals from early- or late convalescence of DENV1 infection to investigate the evolution of anti-DIII human IgG with the time lapse since the infection. We evaluated the correlation between the serotype-specific reactivity against recombinant DIII proteins and the neutralization capacity against the four serotypes, and examined its behavior with the time of convalescence. Also, we use a library of 71 alanine mutants of surface-exposed amino acid residues to investigate the dominant epitopes. In early convalescence anti-DIII titers and potency of virus neutralization were positively associated with correlation coefficients from 0.82 to 1.0 for the four serotypes. For late convalescence, a positive correlation (r = 0.69) was found only for DENV1. The dominant epitope of the type-specific response is centered in the FG-loop (G383, E384, and K385) and includes most of the lateral ridge. The dominant epitope of the anti-DIII cross-reactive IgG in secondary infections shifts from the A-strand during early convalescence to a site centered in residues E314-H317 of the AB-loop and I352-E368 of the DI/DIII interface, in late convalescence. An immunoassay based on the detection of IgG anti-DIII response can be implemented for detection of infecting serotype in diagnosis of DENV infection, either primary or secondary. Human dominant epitopes of the cross-reactive circulating antibodies change with time of convalescence.
Asunto(s)
Virus del Dengue , Dengue , Humanos , Epítopos , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Formación de Anticuerpos , Convalecencia , Proteínas del Envoltorio Viral , Proteínas Recombinantes/metabolismo , Inmunoglobulina G/metabolismo , Reacciones CruzadasRESUMEN
Dengue complex is formed by four viral serotypes that cause the disease of the same name. Dengue is the arthropod-borne disease with the highest incidence worldwide. The envelope glycoprotein comprises three structural domains. The domain III (DIII) induces neutralizing antibodies and is involved in the interactions with soluble plasma factors from human host. Recombinant DIII proteins have been used as analytical tools for the characterization of virus-host interactions and have been evaluated as sub-unit vaccines. Here, we report a purification procedure of recombinant DIII protein and seventy-four alanine mutants refolding by size exclusion chromatography that allows obtaining highly homogeneous protein preparations and suitable for efficient purification and folding check. Four positions are identified that significantly affect either the protein expression or folding of recombinant DIIIE1, K310, G304, D330 and P332.
RESUMEN
Introduction: Subjects with asymptomatic infections are not generally admitted to health care facilities, however, they may benefit from antiviral therapy. Objective: To evaluate the contribution to treatment with combined therapy based on recombinant human interferon alpha 2b + Lopinavir/Ritonavir + Chloroquine versus Lopinavir/Ritonavir + Chloroquine in asymptomatic and symptomatic patients. Material and Methods: An observational study was carried out in patients with a positive diagnosis of COVID-19 from April 1st to July 30th, 2020. From a total of 308 patients treated with interferon + Lopinavir/Ritonavir + Chloroquine, we selected a statistically representative sample of 40 patients using a simple randomization process. As a control group, 27 patients who only received treatment with Lopinavir/Ritonavir + Chloroquine were selected. These patients underwent determinations of anti-SARS-CoV-2 antibodies, determinations of inflammatory markers, and follow-up by RT-PCR to evaluate the time length of negativization. Results: The group treated with interferon had a significantly shorter time to negativization. Patients treated with interferon showed a significant decrease in inflammatory markers at the time of hospital discharge and they had an increase in antibody titers at two and four months after hospital discharge, compared to the group of patients who did not receive interferon. Conclusions: The treatment with exogenous interferon in patients with COVID-19 had a significant contribution to the regulation of the immune response of the patients(AU)
Introducción: Los sujetos con infección asintomática generalmente no son admitidos en centros de asistencia médica, sin embargo, pueden beneficiarse de la terapia antiviral. Objetivo: evaluar la contribución al tratamiento de la terapia combinada basada en interferón alfa 2b recombinante humano + Lopinavir/Ritonavir + Cloroquina contra Lopinavir/Ritonavir + Cloroquina en pacientes asintomáticos y sintomáticos. Material y Métodos: Se realizó un estudio observacional en pacientes con diagnóstico positivo de COVID-19, durante los días del 1 de abril al 30 de julio de 2020. De un total de 308 pacientes tratados con interferón + Lopinavir/Ritonavir + Cloroquina, se seleccionaron mediante un proceso de aleatorización simple, una muestra estadísticamente representativa de 40 pacientes. Como grupo control se seleccionaron 27 pacientes que solo recibieron tratamiento con Lopinavir/Ritonavir + Cloroquina. Estos pacientes se sometieron a determinaciones de anticuerpos anti-SARS-CoV-2, determinaciones de marcadores inflamatorios y seguimiento por RT-PCR para evaluar el tiempo de negativización. Resultados: El grupo tratado con interferón tuvo un tiempo significativamente más corto de negativización. Los pacientes tratados con interferón mostraron una disminución significativa de los marcadores inflamatorios en el momento del alta hospitalaria y tuvieron un incremento de los títulos de anticuerpos a los dos y cuatro meses posteriores al alta hospitalaria, en comparación con el grupo de pacientes que no recibió interferón. Conclusiones: El tratamiento con interferón exógeno en pacientes con COVID-19 tuvo una contribución significativa en la regulación de la respuesta inmune de los pacientes(AU)
Asunto(s)
HumanosRESUMEN
ABSTRACT Introduction: The detection of SARS-CoV-2 genetic material from nasopharyngeal swab samples by RT-PCR is the most specific and sensitive way to test suspected cases. However, factors such as the sampling process, the type of hyssop used, and the anatomical area from which the sample is collected can distort the result and cause false negatives. Objective: To evaluate the reliability of CNUERO hyssops for sample collection for the SARS-CoV-2 diagnosis versus IMPROSWAB hyssops. Material and Methods: To study the reliability of hyssops developed in Cuba for swabbing for the COVID-19 diagnosis by comparing them to other hyssops successfully used for this task, 2 swabbing samples were obtained from each patient (136). One of these two samples was taken using the hyssops made in Cuba, while the other was taken using another hyssop imported from Germany. The positive detections obtained with the use of both hyssops were compared using the Fisher's exact test. The result of the detection of each hyssop was evaluated and compared using the ROC curve. Results: The use of CNEURO hyssops allowed the detection of 45 out of 59 positive cases, while IMPROSAWAB hyssops detected 52 out of 59 true positive cases. There were no significant differences between positive cases detected with the use of each hyssop. The sensitivity of sample detection using CNEURO hyssops was 76,3 % while the one using IMPROSWAB hyssops was 88,1 %. Hence, there are no significant differences in the detection of cases using these two hyssops. Conclusion: CNEURO hyssops are safe and reliable to be used to take nasopharyngeal samples from COVID-19 patients.
RESUMEN Introducción: La detección de material genético del SARS-CoV-2 a partir de muestras de hisopos nasofaríngeos mediante RT-PCR es la forma más específica y sensible de analizar los casos sospechosos. Sin embargo, factores como el proceso de toma de muestra, el tipo de hisopo y el área anatómica de la que se extrae la muestra, pueden distorsionar el resultado y provocar falsos negativos. Objetivo: Evaluar la confiabilidad de hisopos CNUERO para la recolección de muestras en el diagnóstico de SARS-CoV-2 versus hisopos IMPROSWAB. Material y Métodos: Se obtuvieron 2 muestras de exudado de cada paciente (136). Una de estas dos muestras se tomó con hisopos CNEURO, mientras que la otra se tomó con el hisopo IMPROSWAB. Las detecciones positivas entre ambos hisopos se compararon mediante la prueba exacta de Fisher. El resultado de la detección de cada hisopo se evaluó y comparó utilizando la curva ROC. Resultados: El uso de hisopos CNEURO permitió detectar 45 de 59 casos positivos, mientras que los hisopos IMPROSAWAB detectaron 52 de 59 casos verdaderos positivos. Se detectaron diferencias no significativas entre los casos positivos detectados entre hisopos. La sensibilidad de detección de muestras utilizando hisopos CNEURO fue del 76,3 % y del 88,1 % cuando se utilizaron hisopos IMPROSWAB. Por tanto, no se detectaron diferencias significativas en la detección de casos utilizando estos dos hisopos. Conclusión: Los hisopos CNEURO son seguros y fiables para su uso en la toma de muestras nasofaríngeas de pacientes con COVID-19.
Asunto(s)
HumanosRESUMEN
Introduction: The SARS-CoV-2 virus is a positive-strand RNA virus. The virus can also be detected in many different specimens as throat swabs, nasal swabs, sputum, saliva, blood, etc. Objective: The aim of this paper is to compare the reliability of different types of specimen collection, saliva and swabs samples for the detection of SARS-CoV-2. Material and Methods: A sample of 22 COVID-19 positive patients was selected. Paired samples from saliva, nasopharyngeal, oropharyngeal and nasopharyngeal + oropharyngeal swabs were collected on the 7th day after diagnosis. The hyssops and medium employed was IMPROSWAB and IMPROVIRAL NAT Medium, Germany. The sample evaluation was conducted through RT-PCR. The results were compared using Fisher's exact test and ROC curve. The gold standard proposed in this paper was the nasopharyngeal + oropharyngeal swabs specimen. Results: The gold standard method detected 10 true positive cases, of which oropharyngeal swabs, nasopharyngeal swabs and saliva only detected three positive cases. Significant differences (Fisher's exact test p = 0.003) were detected in the comparison between saliva and the gold standart proposed. The ROC curve analysis showed that saliva had an area under the curve of 0.650, with a 30 percent of sensibility. However, the nasopharyngeal and nasopharyngeal + oropharyngeal samples had an area under curve of 0.950 and 1.000, respectively, with a sensibility of 90 percent and 100 percent, respectively. Conclusion: Saliva samples are not a reliable specimen for SARS-CoV-2 RNA detection. In turn, the most reliable specimens are nasopharyngeal and nasopharyngeal + oropharyngeal samples collected by swabbing(AU)
Introducción: El SARS-CoV-2 es un virus ARN positivo. Este virus puede ser detectado en diferentes tipos de secreción como hisopada bucal, nasal, esputo, saliva, sangre, etc. Objetivo: El objetivo de este estudio es comparar la confiabilidad de diferentes tipos de muestras, saliva y exudado, en la detección de SARS-CoV-2. Material y Métodos: Una muestra de 22 pacientes con diagnóstico de Covid-19 fue estudiada. Se tomaron muestras pareadas de saliva y exudado nasofaríngeo y orofaríngeo en cada paciente. Se emplearon los hisopos y medios de la firma alemana IMPROVE®. Los resultados de las determinaciones por RT-PCR se compararon mediante test de Fisher (test de la probabilidad exacta de Fisher) y cada sets de muestras fue evaluada individualmente y luego comparadas por curvas ROC. El estándar de oro propuesto fue el doble hisopado nasofaríngeo/orofaríngeo. Resultados: El método de oro propuesto detectó 10 casos positivos. La coincidencia de detección entre todos los sets de muestras fue de 3 casos (30 por ciento). Se obtuvieron diferencias significativas (Fisher p = 0.003) en la comparación de los casos detectados en saliva vs el estándar de oro. El análisis de curvas ROC mostró un área bajo la curva de 0.650 (30 por ciento de sensibilidad) para la saliva. En el caso del hisopado nasofaríngeo y el estándar de oro mostraron un área bajo la curva de 0.95 y 1.00, respectivamente, con una sensibilidad del 90 (AU) por ciento y 100 por ciento, respectivamente. Conclusiones: La saliva no es una muestra confiable para la detección de SARS-CoV-2. La muestra más confiable para el diagnóstico fue el hisopado nasofaríngeo y el doble hisopado(AU)