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COVID-19 has had severe consequences worldwide. It has been estimated that the contribution of genetic factors to the disease is about 50%. The A16974C polymorphism of the IL-12 p40 gene has been described as being related to resistance or susceptibility to other infectious diseases; therefore, it is likely that it can also be related to COVID-19. The objective of this study was to describe the relationship between the A16974C polymorphism of the IL12 p40 gene with clinical forms of COVID-19 in Cuban patients. The genotypes of the A16974C polymorphism of gene IL-12 p40 were determined through PCR in 102 persons with a COVID-19 epidemiologic discharge from the hospital. In this research, the CC genotype of this polymorphism was found only in symptomatic cases of this disease; since there are signs of relationship between the A16974C polymorphism of the IL12 p40 gene with clinical forms of COVID-19 in the studied Cuban patients, the variations of this polymorphism may be a predisposing risk factor in the development of COVID-19.

La uveítis anterior no infecciosa es una enfermedad inflamatoria del ojo que afecta al tracto uveal y que puede causar ceguera total y otras discapacidades visuales. Esta enfermedad se ubica en el espectro de enfermedades autoinmunes y autoinflamatorias. Se han descrito respuestas no adecuadas a la vacunación en enfermedades mediadas por el sistema inmune, por lo que se evaluaron los niveles de antitoxina tetánica y diftérica en pacientes cubanos con uveítis anterior no infecciosa, relacionada con el alelo HLA-B27. Se determinaron los niveles de antitoxina tetánica y diftérica mediante ELISA en 190 pacientes con uveítis anterior no infecciosa y controles supuestamente sanos. El 97,37% de los pacientes con uveítis mostraron niveles de protección de antitoxina tetánica mayor o igual a 0,1 UI/mL, similar a lo observado en los controles sanos (98,95%) (p=0,4385). Las proporciones de pacientes con uveítis anterior no infecciosa y sus controles en los diferentes niveles de protección de antitoxina tetánica fueron similares (p>0,05), al igual que los títulos medios geométricos (p=0,2907). En los pacientes con uveítis, de 65 años o más, se detectó una mayor proporción de individuos con títulos protectores de larga duración (>1,0 UI/mL) de antitoxina diftérica (p=0,0065). En los pacientes con uveítis no se observó asociación entre la presencia del alelo HLA-B27 y la respuesta de anticuerpos frente al toxoide tetánico (p=0,6196) y diftérico (p=0,1917). El 37,9% de los pacientes con uveítis y el 42% de los controles, presentaron títulos no protectores (

BackgroundTumor necrosis factor-alpha (TNFɑ) is a cytokine that manages the host defense mechanism, which may play a role in the pathogenesis of COVID-19 patients. Several single-nucleotide polymorphisms, described in the promoter region of the TNFα gene, have a significant role on its transcriptional activity. These include the − 308A > G polymorphism which increases the TNFα levels with the expression of the A allele. The aim of this study was to explore whether the TNFα.− 308A > G polymorphism affects the clinical state of COVID-19 patients. The study included a total of 1028 individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which were distributed in 3 groups: asymptomatic, mild symptomatic and severe symptomatic patients. The amplification-refractory mutation system was used to determine the genotype of the TNFα.− 308A > G polymorphism.ResultsResults show a higher tendency of being asymptomatic in individuals carrying the GG genotype (336 of 411; OR 1.24, 95% CI 0.91–1.70). The development of a severe form of SARS-CoV-2 infection was not found in subjects with the A allele compared to those with the G allele (OR 0.96, 95% CI 0.51–1.79), except in the eastern region of the country where the risk increased (OR 4.41, 95% CI 1.14–17.05). However, the subjects carrying the A allele had a higher chance of developing symptoms (OR 1.24, 95% CI 0.91–1.70) compared to those with the G allele.ConclusionThe TNFα.− 308A allele has an influence on developing symptoms of COVID-19 in Cuban patients, and that it particularly increases the risk of presenting severe forms of the disease in the eastern region of the country.

Purpose To determine the relationship between the genotypes of the TaqI polymorphism of VDR gene and the clinical forms of COVID-19 in Cuban patients. Methods TaqI polymorphism was determined by the PCR in 104 Cuban patients, who suffered different clinical forms of COVID-19. Results There was a greater possibility of presenting symptomatic forms [OR = 2.081, 95% CI: 0.243–17.842], even severe [OR = 1.200, 95% CI: 0.217–6.638], related to the tt genotype. Conclusion There are signs of association between the risk of developing COVID-19 and the genotypes of the TaqI polymorphism of the VDR gene in the studied Cuban patients.

The immune response during and after SARS-CoV-2 infection can be complex and heterogeneous, and it can be affected by the severity of the disease. It can also contribute to an unfavorable evolution and bring about short and long term effects. The aim of this study was to characterize the lymphocyte composition according to the severity of COVID-19, as well as its degree of relationship to the specific humoral response to SARS-CoV-2 in convalescents up to 106 days after the infection and in their exposed relatives.An applied research was carried out with a cross-section analytical design, from March 11 to June 11, 2020 in Cuba. The sample consisted of 251 convalescents from COVID-19 over 18 years of age and 88 exposed controls who did not become ill. The B and T cell subpopulations, including memory T cells, as well as the relationship with the humoral immune response against SARS-CoV-2, were identified by flow cytometry and enzyme immunoassay.Convalescent patients, who evolved with severe forms, showed a decrease in frequency and a greater proportion of individuals with values ​​lower than the minimum normal range of B cells, CD3 + CD4 + cells and the CD4 + / CD8 + ratio, as well as a higher frequency and a greater proportion of individuals with values ​​above the normal maximum range of CD3 + CD8 + and NK cells. Convalescent patients with severe forms of COVID-19 that exhibited IgG / RBD titers ≥ 1/200 had a lower frequency of TEMRA CD8 + cells (p = 0.0128) and TEMRA CD4 + (p = 0.0068). IgG / RBD titers were positively correlated with the relative frequency of CD4 + CM T memory cells (r = 0.4352, p = 0.0018).The identified alterations of B and T lymphocytes suggest that convalescent patients with the severe disease could be vulnerable to infectious, autoimmune or autotinflammatory processes; therefore, these individuals need medical follow-up after recovering from the acute disease. Furthermore, the role of T cells CD4 + CM in the production of antibodies against SARS-CoV-2 is confirmed, and it is noted that the defect of memory T cells CD8 + TEMRA could contribute to the development of severe forms of COVID-19.

Background: the relationship between the reduced and oxidized form of glutathione, GSH/ GSSG, is frequently used as an indicator of the cellular redox state. Under conditions where high levels of oxidizing species are generated, reduced glutathione requirements can be increased, and therefore, the cellular redox state can be affected. Objective: to determine the relationship between the cellular redox state and systemic markers of inflammation. Methods: a descriptive study was carried out in a series of 56 cases referred from the immunogenetics clinic, aged between 1 and 76 years old, of both sexes. Erythrocyte sedimentation rate and serum levels of C-reactive protein were determined as systemic markers of inflammation. The GSH/GSSG ratio was calculated from the intraerythrocyte concentrations of reduced glutathione and its oxidized form, which were determined by an HPLC-UV method. Results: the average GSH/GSSG ratio was 7.9 (95 % CI: 6.4-9.4) and age did not influence this proportion. In the cases that had altered values of the inflammation markers, they showed a decrease in the GSH/GSSG ratio. Cellular redox status was negatively correlated with erythrocyte sedimentation values (r=0.41; p=0.017). However, this association does not appear when C-reactive protein levels are analyzed. Conclusions: the patients who present alterations in the inflammation markers show changes in the cellular redox state. The combined study of these biomarkers allows a more comprehensive analysis of the health status of patients with inflammatory diseases.

Introduction: Diphtheria still persists in many countries. In Cuba, studies conducted in different age groups have demonstrated that there are non-protective levels of diphtheria antitoxin in the population, so it is necessary to have methods that allow the serologic survey of population immunity. The quantification of antibodies against vaccine antigens such as diphtheria toxin is also a useful, rapid and economic method to evaluate the immune response.Objective: To validate an ELISA-type immune-enzymatic test to quantify the levels of diphtheria antitoxin in human serum.Material and Method: An experimental study of technological development was carried out in the Immunology Laboratory of the National Medical Genetics Center, Havana, Cuba. The optimal values of the variables that influence on the result of the indirect heterogeneous immune-enzymatic test for the quantification of diphtheria antitoxin were determined. The calibration curve obtained was evaluated against the WHO standard (Diphtheria Antitoxin Human Serum 00/496). The analytical validation of the standardized method was performed.Results: The intra-assay and inter-assay coefficients of variation were less than 10% and 20%, respectively. Recovery values between 90 and 110% were found in accuracy and selectivity. The parallelism between the standard curve and the samples studied showed a coefficient of variation lower or equal to 10%. The limit of quantification was 0,015 IU/mL and the one of detection was 0,0039 IU/mL. Conclusions: The result obtained in the precision, accuracy and selectivity of the ELISA-type immune-enzymatic test developed and validated in the National Medical Genetics Center demonstrated that it can be used in the clinical practice to quantify the values of diphtheria antitoxin in human serum.Keywords: diphtheria antitoxin, immune-enzymatic test, ELISA, validation.

Background: As a first step towards a vaccine protecting COVID-19 convalescents from reinfection, we evaluated FINLAY-FR-1A vaccine in a clinical trial. Methods: Thirty COVID-19 convalescents aged 22-57 years were studied: convalescents of mild COVID-19, asymptomatic convalescents, both with PCR-positive at the moment of diagnosis; and individuals with subclinical infection detected by viral-specific IgG. They received a single intramuscular injection of the FINLAY-FR-1A vaccine (50 µg of the recombinant dimeric receptor binding domain). The primary outcomes were safety and reactogenicity, assessed over 28 days after vaccination. The secondary outcome was vaccine immunogenicity. Humoral response at baseline and following vaccination was evaluated by ELISA and live-virus neutralization test. The effector T cellular response was also assessed. Cuban Public Registry of Clinical Trials, WHO-ICTRP: https://rpcec.sld.cu/en/trials/RPCEC00000349-En. Findings: No serious adverse events were reported. Minor adverse events were found, the most common, local pain: 3 (10%) and redness: 2 (6·7%). The vaccine elicited a >21 fold increase in IgG anti-RBD antibodies 28 days after vaccination. The median of inhibitory antibody titres (94·0%) was three times greater than that of the COVID-19 convalescent panel. Virus neutralization titres higher than 1:160 were found in 24 (80%) participants. There was also an increase in RBD-specific T cells producing IFN-I³ and TNF-α. Interpretation: A single dose of the FINLAY-FR-1A vaccine against SARS-CoV-2 was an efficient booster of pre-existing natural immunity, with excellent safety profile. Funding: Partial funding for this study was received from the Project-2020-20, Fondo de Ciencia e Innovacion (FONCI), Ministry of Science, Technology and the Environment, Cuba.   RESUMEN. Antecedentes: Como un primer paso hacia una vacuna que proteja a los convalecientes de COVID-19 de la reinfeccion, evaluamos la vacuna FINLAY-FR-1A en un ensayo clinico. Metodos: Se estudiaron treinta convalecientes de COVID-19 de 22 a 57 anos: convalecientes de COVID-19 leve y convalecientes asintomaticos, ambos con prueba PCR positiva al momento del diagnostico; e individuos con infeccion subclinica detectada por IgG especifica viral. Los participantes recibieron una dosis unica por via intramuscular de la vacuna FINLAY-FR-1A (50 µg del dominio de union al receptor recombinante dimerico del SARS CoV-2). Las variables de medida primarias fueron la seguridad y la reactogenicidad, evaluadas durante 28 dias despues de la vacunacion. La variable secundaria, la inmunogenicidad. La respuesta humoral, al inicio del estudio y despues de la vacunacion, se evaluo por ELISA y mediante la prueba de neutralizacion del virus vivo. Tambien se evaluo la respuesta de celulas T efectoras. Registro Publico Cubano de Ensayos Clinicos, WHO-ICTRP: https://rpcec.sld.cu/en/trials/RPCEC00000349-En. Resultados: No se reportaron eventos adversos graves. Se encontraron eventos adversos leves, los mas comunes, dolor local: 3 (10%) y enrojecimiento: 2 (6·7%). La vacuna estimulo un incremento >21 veces de los anticuerpos IgG anti-RBD 28 dias despues de la vacunacion. La mediana de los titulos de anticuerpos inhibidores (94·0%) fue aproximadamente tres veces mayor que la del panel de convalecientes de COVID-19. Se encontraron titulos de neutralizacion viral superiores a 1:160 en 24 (80%) de los participantes. Tambien hubo un aumento en las celulas T especificas de RBD que producen IFN-I³ y TNF-α. Interpretacion: Una sola dosis de la vacuna FINLAY-FR-1A contra el SARS-CoV-2 reforzo eficazmente la inmunidad natural preexistente, con un excelente perfil de seguridad. Financiamiento: Se recibio un financiamiento parcial del Proyecto-2020-20, Fondo de Ciencia e Innovacion (FONCI), Ministerio de Ciencia, Tecnologia y Medio Ambiente, Cuba.

Introduccion: Durante la etapa aguda de la infeccion por el virus de la hepatitis B y el periodo inicial de una infeccion cronica, el DNA esta en forma episomal (libre o extracromosomal) y replica en el hepatocito produciendo entre otros viriones infectivos, DNA polimerasa y antigeno de superficie del virus (HBsAg). Objetivo: Validar un inmunoensayo tipo ELISA para cuantificar los niveles de HBsAg en pacientes con hepatitis B cronica. Metodo: Se realizo un estudio experimental de desarrollo tecnologico. Se llevo a cabo la normalizacion y validacion de un inmunoensayo enzimatico heterogeneo de doble anticuerpo para la cuantificacion de HBsAg en sueros humanos. 115 muestras de sueros de pacientes con hepatitis B cronica con resultados de carga viral se correlacionaron con las concentraciones de HBsAg. Resultados y discusion: El metodo presento coeficientes de variacion intra e interensayo de 9,8 y 13,2% respectivamente. El rango de trabajo se estimo entre 0.15 y 60ng/mL. El porcentaje de recuperacion estuvo entre el 90 y 110% y el ajuste lineal de la curva estandar presento un coeficiente de determinacion superior a 0,99. La correlacion alcanzada entre los niveles de DNA y la concentracion de HBsAg fue de 62.5%. Conclusiones : La evaluacion del ELISA para la cuantificacion de HBsAg desarrollado en el laboratorio mostro que cumple los parametros de validacion para su uso clinico.

Introducción: la cuantificación de antitoxina tetánica es útil para la evaluación de la respuesta inmune humoral frente a antígenos vacunales. Objetivo: desarrollar la estandarización y validación técnica de un ensayo de inmunoabsorción ligado a enzima (ELISA) de tipo indirecto para cuantificar antitoxina tetánica en suero humano. Material y Método: el estándar preparado para la curva del ensayo se calibró frente al preparado en el Instituto Finlay. Se normalizaron los indicadores óptimos para el desarrollo de cada paso de la técnica. Resultados y Discusión: durante la validación se alcanzó una buena precisión intraensayo e interensayo en todos los casos. Al evaluar el paralelismo el coeficiente de variación fue menor de 10%. El ensayo mostró una excelente exactitud, con valores de recuperación entre 90% y 110%. El límite de detección fue 0,002 UI/mL. La sensibilidad analítica alcanzada fue de 0,01 UI/mL. Conclusiones: el ensayo puede ser utilizado para la cuantificación de antitoxina tetánica en suero humano. Palabras clave: antitoxina tetánica, ensayo inmunoenzimático, ELISA, validación.