Research Progress in Antibody Responses Against SARS-CoV-2 Variants of Concern / 中国医学科学院学报

So far,the coronavirus disease 2019(COVID-19)has been persisting for nearly three years,infecting about 700 million people and causing more than 6 million deaths,which has seriously affected the human society.According to Global Initiative on Sharing All Influenza Data,there are more than 12 million SARS-CoV-2 variants,of which the five major variants of concern are Alpha,Beta,Gamma,Delta and Omicron.Their infectivity,pathogencity,and neutralization resistance have changed greatly compared with the original strain,which has brought great pressure to the prevention and control of the pandemic.Antibody level testing is critical for confirming infection,epidemiological investigation,vaccine development,and neutralizing drug preparation.Focusing on the humoral immunity against SARS-CoV-2,this paper introduces the mutation sites,neutralization resistance,and vaccination efficacy of the five variants of concern,and briefly summarizes the evolutionary characteristics,future mutation directions,and host immunity.

Manejo clínico y diagnóstico para pacientes con enfermedades de inmunodeficiencia primaria por déficit de producción de anticuerpos / Clinical management and diagnosis for patients with primary immunodeficiency diseases due to deficiency of antibody production

1. INTRODUCCIÓNLas inmunodeficiencias primarias son un grupo de más de 400 enfermedades, en las cuales el sistema inmune pierde sus funciones de reconocimiento de patógenos o funciona de forma inapropiada. Algunas de ellas son relativamente comunes; mientras otras son raras. Estas enfermedades son en ocasiones de por vida, debilitantes y costosas1,2.Sin embargo, muchos progresos se han hecho desde su des-cripción original en el año de 1952. Se han dado grandes pasos en cuanto a su entendimiento de las Inmunodeficiencias Pri-marias a nivel genético, de sus características, y tratamiento. Algunos tipos afectan un único tipo de célula; otros afectan más de un componente del sistema inmune2,3.Tomando en cuenta que la aproximación es entre 1-2% de la población, a nivel país se puede decir que un aproximado entre 170 000 a 340 000 pacientes en el país no cuentan con un diagnóstico y muchos mueren por falta de este. El número de afiliados al Instituto Ecuatoriano de Seguridad Social hasta julio de 2021 es de 3 672,611 por lo que se considera que un estimado de 36 726 a 73 452 pacientes podrían presentar este tipo de enfermedades y requerir de atención por infecciones a repetición, enfermedad autoinmune y enfermedades linfopro-liferativas, además de que sin un tratamiento específico po-drían fallecer debido a infecciones graves o tener discapacidad permanente, lo que implica mayor carga para el sistema de Seguridad Social en subsidios y menores ingresos. Ecuador, cuenta con 86 pacientes diagnosticados, según la base de datos de la Sociedad Latino-Americana de Inmunodeficiencias4.Algunas terapias, como la de reemplazo para inmunoglobu-linas, a la que es tributaria más del 60% de estas patologías permite que la esperanza de vida y la morbilidad casi alcancen a aquellos que no presentan la enfermedad5­7.

1. INTRODUCTIONPrimary immunodeficiencies are a group of more than 400 diseases, in which the immune system loses its pathogen recog-nition functions or functions inappropriately. Some of them are relatively common, while others are rare. These diseases are sometimes lifelong, debilitating, and costly1,2. However, much progress has been made since its original description in 1952. Great strides have been made in understanding Primary Immunodeficiencies at the genetic level, their characteristics, and treatment. Some types affect only one type of cell; others affect more than one component of the immune system2,3. Considering that the approximation is between 1 to 2% of the population, at the country level we could say that approximately between 170 000 to 340 000 patients in the country do not have a diagnosis and many die due to lack of it. The number of social security affiliates until July 2021 is 3 672,611, so we could consider that approximately 36 726 to 73 452 patients could present this type of disease and require care for recurrent infections, autoimmune disease and lymphoproliferative diseases, in addition to the fact that without specific treatment they could die due to serious infections or have permanent disability, which implies a greater burden for the social security system in subsidies and lower income. Currently the country has 86 diagnosed patients, according to the database of the Latin American Society of Immunodeficiencies4. Many of the therapies, such as immunoglobulin replacement therapy, to which more than 60% of these pathologies are de-pendent, allow life expectancy and morbidity to almost reach those who do not have the disease 5­7.

Effect of dietary plants on the production of immunoglobulins A in healthy Wistar rats / Efeito de plantas dietéticas na produção de imunoglobulinas A em ratos Wistar saudáveis

Introduction: some plants such as turmeric, cinnamon, and okra are known to have therapeutic functions such as antioxidant and anti-inflammatory activity. Furthermore, an immunomodulatory role has been observed in the production of antibodies, in particular immunoglobulin A (IgA), which mediates a variety of protective functions for the organism. Objective: the aim of the present study was to investigate the effect of dietary plants on the production of IgA in healthy Wistar rats. Methods: thus, 48 male Wistar rats of 90 days of age were allocated to four groups. The animals were treated for 14 days with dried turmeric, cinnamon, or okra (50, 50, 12.5 mg/day, respectively) in phosphate buffered saline, or with only phosphate buffered saline by gavage. The animals received water and feed ad libitum. Body mass and relative weight ofperitoneal fat, adrenal gland, kidney, spleen, liver and thymus, biochemical parameters, and IgA levels were analyzed. Results: no significant changes were observed in the body mass, relative weight of organs and tissues, and biochemical parameters. An increase in serum IgA levels was observed in animals treated with turmeric or cinnamon. Conclusion: we conclude that the treatment with turmeric and cinnamon increased IgA production. Therefore, our study supports the idea that dietary supplementation with these plants may improve humoral immunity.

Introdução: algumas plantas como a cúrcuma, a canela e o quiabo são conhecidas por apresentar funções terapêuticas, como atividade antioxidante e anti-inflamatória. Além disso, tem sido observado um papel imunomodulador sobre a produção de anticorpos, em especial a imunoglobulina A (IgA), a qual medeia uma variedade de funções protetoras para o organismo. Objetivo: o objetivo do presente estudo foi investigar o efeito de plantas dietéticas na produção de IgA em ratos Wistar saudáveis. Métodos: destarte, 48 ratos machos Wistar com 90 dias de idade foram alocados em quatro grupos. Os animais foram tratados por 14 dias com cúrcuma seca, canela ou quiabo (50, 50, 12,5 mg/dia, respectivamente) em solução salina tamponada com fosfato ou apenas solução salina tamponada com fosfato, por gavagem. Os animais receberam água e ração ad libitum. Foram analisados a massa corporal e o peso relativo da gordura peritoneal, glândula adrenal, rim, baço, fígado e timo, parâmetros bioquímicos e níveis de IgA. Resultados: não foram observadas alterações significativas na massa corporal, no peso relativo dos órgãos e tecidos e nos parâmetros bioquímicos. Foi observado aumento dos níveis séricos de IgA nos animais tratados com cúrcuma ou canela. Conclusão: podemos concluir que o tratamento com cúrcuma e canela aumentou a produção de IgA. Portanto, nosso estudo suporta a ideia de que a suplementação alimentar com essas plantas pode melhorar a imunidade humoral.

Respuesta humoral inducida por la vacuna BBIBP-CorV/Sinopharm COVID-19 en trabajadores de primera línea / BBIBP-CorV/Sinopharm COVID-19 vaccine-induced humoral response in frontline workers

Con la llegada de la vacuna contra el COVID-19 se evidenció la disminución de casos de Infección por SARS-CoV-2. El objetivo del estudio fue cuantificar la producción de anticuerpos neutralizantes (An) e inmunoglobulina G (S-IgG) en trabajadores de primera línea inmunizados con dos dosis de la vacuna BBIBP-CorV/Sinopharma. Se realizó un estudio observacional analítico transversal en personal de salud inmunizado con la vacuna inactivada (BBIBP-CorV). Sus muestras sanguíneas se recogieron tres meses después de la segunda dosis, para medir las respuestas de anticuerpos (An, S-IgG). De un total de 172 personas evaluadas, 110 (64%) personas ya habían tenido COVID-19 antes de ingresar al estudio, los títulos de An fueron superiores a 10 AU/mL en el 60,5% de los vacunados y el 89,3% mostró S-IgG superior a 50 UA/mL. Los trabajadores mayores de 60 años fueron el grupo que no desarrolló suficientes anticuerpos. La correlación de An y S-IgG fue positiva (r=0,84) (p<0,001). La administración de dos dosis de la vacuna inactivada BBIBP-CorV/Sinopharma provocó una notable respuesta An y S-IgG, excepto en mayores de 60 años(AU)

With the arrival of the vaccine against COVID-19, the decrease in cases of SARS-CoV-2 infection was evidenced. The objective of the study was to quantify the production of neutralizing antibodies (An) and immunoglobulin G (S-IgG) in frontline workers immunized with two doses of the BBIBP-CorV/Sinopharma vaccine. A cross-sectional analytical observational study was carried out in health personnel immunized with the inactivated vaccine (BBIBP-CorV). Their blood samples were collected three months after the second dose, to measure antibody responses (An, S-IgG). Of a total of 172 people evaluated, 110 (64%) people already had COVID-19 before entering the study, An titers were greater than 10 AU/mL in 60.5% of those vaccinated and 89, 3% showed S-IgG greater than 50 AU/mL. Workers older than 60 years were the group that did not develop enough antibodies. The correlation of An and S-IgG was positive (r=0.84) (p<0.001). The administration of two doses of the inactivated BBIBP-CorV/Sinopharma vaccine caused a notable An and S-IgG response, except in those over 60 years of age(AU)

Human follicular helper T lymphocytes critical players in antibody responses / Linfócitos T auxiliares foliculares humanos: células essenciais para a resposta de anticorpos

ABSTRACT Follicular helper T lymphocytes are a subpopulation of CD4+ T lymphocytes initially identified in germinal centers of follicles found in secondary lymphoid organs. The primary function of follicular helper T lymphocytes is to help B lymphocytes' antibody production. Changing of antibody class and affinity, B cell differentiation and memory generation depend on cooperation between follicular helper T lymphocytes and B cells. In blood, follicular helper T lymphocytes are called circulating follicular helper T lymphocytes. They are considered to have specificities similar to those developed in the secondary lymphoid organs. The phenotype of human follicular helper T lymphocytes is given by simultaneous expression of the markers CXCR5, Bcl-6, CD40L, PD-1, and ICOS. In germinal centers, follicular helper T lymphocytes synthesize interleukin 21 as predominant cytokine. In blood, subpopulations of circulating follicular helper T lymphocytes can be recognized, with different expressions of the classical follicular helper T lymphocytes markers and, in addition, can express other markers such as CXCR3 and CCR6. Presently, there is great interest in follicular helper T lymphocytes and circulating follicular helper T lymphocytes in vaccination studies as indicators of immunization efficacy. In addition, follicular helper T lymphocytes are investigated as possible markers of activity in many diseases and potential therapeutic intervention. This short review describes aspects of immunobiology and quantification of follicular helper T lymphocytes and circulating follicular helper T lymphocytes, and presents a few examples of related findings in systemic lupus erythematosus, rheumatoid arthritis, HIV infection and vaccination.

RESUMO Linfócitos T auxiliares foliculares são uma subpopulação de linfócitos T CD4+ identificada inicialmente nos centros germinativos dos folículos dos órgãos linfoides secundários. Sua função primordial é auxiliar os linfócitos B na produção de anticorpos. A mudança de classe e de afinidade dos anticorpos, a diferenciação das células B e a geração de memória dependem da cooperação entre os linfócitos T auxiliares foliculares e as células B. No sangue, recebem o nome de linfócitos T auxiliares circulantes. Considera-se que possuem especificidades semelhantes às desenvolvidas nos órgãos linfoides secundários. O fenótipo dos linfócitos T auxiliares humanos é dado pela expressão conjunta dos marcadores CXCR5, Bcl-6, CD40L, PD-1 e ICOS. Nos folículos, linfócitos T auxiliares sintetizam a interleucina 21 como citocina predominante. No sangue, são descritas várias subpopulações de linfócitos T auxiliares circulantes com expressões variadas dos marcadores clássicos de linfócitos T auxiliares, além de poderem agregar outros, como CXCR3 e CCR6. Existe um enorme interesse no estudo de linfócitos T auxiliares e linfócitos T auxiliares circulantes, para a avaliação de eficácia de vacinação. São também investigados como possíveis marcadores de atividade em muitas doenças e potenciais intervenções terapêuticas. Esta breve revisão descreve aspectos da imunobiologia e da quantificação de linfócitos T auxiliares humanos e linfócitos T auxiliares circulantes, além de apresentar alguns achados relacionados em lúpus eritematoso sistêmico, artrite reumatoide, infecção por HIV e vacinação.

Enhanced epitope immunoreactivity of the dominant epitope of Toxoplasma gondii fused at the "N terminus" of HPV16L1 / 生物工程学报

For improving epitope immunogenicity and achieving the co-immunization, late protein 1 (L1) of HPV type 16 (HPV16L1) was selected as the vector to carry the dominant epitope of Toxoplasma gondii because of the shared common population between Toxoplasma gondii and human papillomavirus (HPV). RSepitope-HPV16L1 (RSepitope fused at the "N-terminus" of HPV16L1) and HPV16L1-RSepitope (RSepitope fused at the "C-terminus" of HPV16L1) chimeras were constructed. After transfection of COS-7 cells with the recombinants, Western blot, RT-PCR, and immunofluorescence experiments confirmed that RSepitope-HPV16L1 could successfully express the corresponding mRNA and protein of RSepitope and HPV16L1, but the HPV16L1-RSepitope construct could not. A "prime-boost" immunization program was applied in mice to further evaluate the immune response elicited by the constructs, and the RSepitope-HPV16L1 immunization group produced the most significantly increased humoral and cellular immune responses (the highest RSepitope-specific IgG antibody level and the highest IFN-γ production, respectively), in which both elevated Th1 and Th2 immune responses were obtained. Moreover, the advantage of HPV16L1 as an epitope carrier was remarkable for RSepitope-HPV16L1, which induced a more prominent immunological response than RSepitope alone (without fusion with HPV16L1). Our research indicated that the N-terminus of HPV16L1 could be a better insertion site for enhancing target epitope immunogenicity, and our study offers a design for epitope vaccine of reasonable combination.

Avaliação da resposta de anticorpos IgG contra diferentes variantes alélicas do Antígeno 1 de Membrana Apical (AMA-1) de Plasmodium vivax em indivíduos de áreas endêmicas de malária / Evaluation of IgG antibody response against different variants of Plasmodium vivax apical membrane antigen 1 (AMA-1) in individuals from malaria endemic areas

O Plasmodium vivax é a espécie com maior distribuição geográfica no mundo e a que predomina nas Américas, incluindo o Brasil. Comparado ao Plasmodium falciparum, poucas vacinas contra o P. vivax encontram-se em fase de testes clínicos. Um dos antígenos de formas sanguíneas de P. vivax candidato a vacina é o Antígeno 1 de Membrana Apical (PvAMA-1). Entretanto, a diversidade antigênica do mesmo na natureza representa um grande desafio para seu uso no desenvolvimento de uma vacina de ampla cobertura. No presente estudo, avaliamos se os polimorfismos de sequências já descritos são capazes de influenciar na eficácia de uma vacina baseada em PvAMA-1. Para isso, geramos 9 proteínas recombinantes a partir da levedura Pichia pastoris, as quais são representativas de diferentes variantes alélicas do antígeno PvAMA-1, a saber: Belem, Chesson I, Sal-1, Indonesia XIX, SK0814, TC103, PNG_05_ESP, PNG_62_MU e PNG_68_MAS. Após expressão e purificação das proteínas selecionadas, avaliamos comparativamente por ELISA a resposta de anticorpos IgG naturalmente adquiridos em indivíduos expostos a malária, procedentes da Região Amazônica. Todas as proteínas foram obtidas com rendimento e pureza apropriados para os estudos propostos. A prevalência total de indivíduos expostos a malária com anticorpos contra PvAMA-1 Belem foi de 53,68%, em 611 amostras de soro testadas. Entre 100 das amostras sorologicamente positivas para PvAMA-1 Belem, os maiores valores de DO492 foram obtidos para as variantes Chesson I, SK0814 e Sal-1, sugerindo que epítopos comuns ou de reatividade cruzada estão sendo reconhecidos nessas variantes. Por outro lado, níveis mais baixos de DO492 foram obtidos para as variantes Indonesia XIX, TC103, PNG_05_ESP, PNG_62_MU e PNG_68_MAS, o que pode significar que essas variantes são menos prevalentes ou não circulam no Brasil. Soros policlonais de camundongos C57BL/6 previamente imunizados com PvAMA-1 Belem foram testados quanto ao reconhecimento das diferentes variantes por ELISA. Nossos resultados demonstraram que as variantes Chesson I, Indonesia XIX, SK0814, Sal-1 e a proteína homóloga foram predominantemente reconhecidas. Por fim, ensaios de competição baseados em ELISA revelaram que as proteínas Chesson I, Indonesia XIX, SK0814 e Sal-1, na fase solúvel, foram capazes de inibir a ligação de anticorpos à variante Belem aderida a placa, sugerindo a presença de epítopos comuns ou de reatividade cruzada entre as mesmas. Nossos dados sugerem que uma vacina baseada na variante PvAMA-1 Belem gera anticorpos variante-transcendentes. Entretanto, para gerar uma vacina universal baseada em PvAMA-1, uma formulação multi-alélica, incluindo variantes da Tailândia e Papua Nova Guiné, deverão ser testadas

Plasmodium vivax has the largest geographical distribution Plasmodium species in the world, and is predominant in the Americas, including Brazil. Fewer P. vivax vaccines than P. falciparum vaccines have successfully reached clinical trials. One of the candidate antigens for a blood-stage P. vivax vaccine is the apical membrane antigen 1 (PvAMA-1). However, the high natural variability found in this antigen presents a major challenge for its development into a wide-range vaccine. In the present study, we evaluated whether sequence polymorphisms would influence a vaccine based on PvAMA-1. To achieve this, we generated 9 recombinant proteins from the yeast Pichia pastoris, representative of different allelic variants of the PvAMA-1 antigen: Belem, Chesson I, Sal-1, Indonesia XIX, SK0814, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS. After expression and purification of these proteins, we compared, by ELISA and IgG blocking, the natural acquired response from malaria-exposed individuals in the Amazon Region. All proteins selected had the appropriate yield and purity for the proposed studies. The total prevalence of malaria-exposed individuals with reactivity to PvAMA-1 Belem was 53,68%, from 611 serum samples tested. One hundred of these serologically positive samples were further tested against recombinant proteins representing the other allelic variants. The highest OD values resulted from Sal-1, Chesson I and SK0814 variants, suggesting that common epitopes or cross-reactivity exist across the variants. On the other hand, the lowest OD values resulted from the variants Indonesia XIX, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS, which may mean these variants are less prevalent or do not circulate in Brazil. Polyclonal sera from C57BL/6 mice immunized with PvAMA-1 Belem were tested for recognition of different variants by ELISA. Our results showed that the variants Chesson I, Sal-1, Indonesia XIX, SK0814 and the homologous protein were predominantly recognized. Lastly, ELISA-based competition assays revealed that Chesson I, Sal-1, Indonesia XIX and SK0814 proteins were able to inhibit antibody binding to the Belem variant, suggesting the presence of common epitopes or cross-reactivity between these variants. Our data suggest that a vaccine based on the PvAMA-1 Belem variant displays strain-transcendent antibodies. However, to generate a universal vaccine based on PvAMA-1, a multiallelic formulation including variants from Thailand and Papua New Guinea must be tested

Association between circulating exhausted CD4+ T cells with poor meningococcal C conjugate vaccine antibody response in HIV-infected children and adolescents

OBJECTIVES: To investigate the expression levels of surface markers of activation (CD38 and HLA-DR), inhibition (PD-1, TIGIT and CD57) and co-stimulation (CD28 and CD127) on CD4+ T cells of children/adolescents with vertical HIV infection (HI patients) and HIV-uninfected (HU) controls vaccinated with the meningococcal C conjugate vaccine (MCC). METHODS: HI patients (n=12), aged 8-17 years, were immunized with two MCC injections, while HU controls (n=9), aged 5.3-10.7 years, received a single MCC dose (as per national recommendation at the time of this study, a single MCC vaccine dose should be given for healthy children and youth aged 1-18 years). The HI patients were categorized according to the combined antiretroviral therapy (cART) treatment. Blood samples were obtained before vaccination, after priming, and after the administration of a booster dose of vaccine to determine the serum bactericidal antibody (SBA) titers and the expression levels of surface markers on CD4+ T cells by flow cytometry. The levels of serum cytokines, IL-4 and CXCL-13 were also measured using Luminex kits. RESULTS: The co-expression of the TIGIT-HLA-DR-CD38 molecules increased in the CD4+ T cells of HI patients/no-cART who also showed a lower frequency of CD127+CD28+ CD4+ T cells than HI patients/cART and HU group subjects. There were significant negative correlations between the frequency of exhausted CD4+ T cells and the SBA response. IL-4 levels were higher in HI patients/cART and positively correlated with SBA titers but negatively associated with the expression of exhaustion markers. Moreover, the CXCL-13 levels were positively correlated with the exhausted CD4+ T cells. CONCLUSION: The results of our study suggest that the co-expression of exhaustion markers and/or loss of co-stimulatory molecules influence the SBA response in HI patients.

El síndrome de fatiga crónica en el curso de la hepatitis C. Presentación de un caso / Chronic fatigue syndrome in the course of Hepatitis C

RESUMEN Se supone que aproximadamente 80 millones de personas a nivel mundial están infectadas con el virus de la hepatitis C. Un aproximado del 60 % de dichos pacientes aqueja síndrome de fatiga crónica. Se presentó un paciente portador de hepatitis crónica de tipo C, con manifestaciones clínicas de síndrome de fatiga crónica por más de dos años. Se han reportado estudios internacionales que han demostrado la relación existente entre el desarrollo de la respuesta inmune y el daño que ocasiona en el tejido cerebral la infección por virus de hepatitis C. Este trabajo tiene como objetivo la presentación del primer caso que se tiene referencia (AU).

ABSTRACT It is believed that almost 80 million persons are infected with the Hepatitis C virus around the world, and 60 % of them suffer the chronic fatigue syndrome. For that reason we present the case of a patient who is a carrier of the chronic fatigue syndrome for more than two years. Reports of international research have showed the relation between the immune answer and the damage caused by the infection of the hepatitis C virus in the brain tissues. The aim of this work is presenting the first case reported in Cuba (AU).

Uso complementario de las pruebas moleculares y pruebas de detección de anticuerpos para el diagnóstico de COVID-19 / Complementary use of molecular tests and antibody screening tests for the diagnosis of COVID-19

ANTECEDENTES: El COVID-19 es una infección producida por una cepa de coronavirus denominada SARS-CoV-2. En la actualidad, esta infección es una pandemia que afecta a más de 209 países y territorios a nivel mundial. En el Perú, se han reportado hasta el 07 de abril de 2020, 2 954 casos y un total de 107 fallecidos. El diagnóstico rápido de la infección juega un papel importante en el manejo de la enfermedad y de los brotes, permitiendo implementar medidas de vigilancia, prevención y control. Una dificultad para el diagnóstico oportuno es la gran proporción de portadores asintomáticos del virus, quienes representan un contribuyente importante en la propagación de la enfermedad. El método estándar para el diagnóstico de COVID-19 es la prueba molecular basada en la reacción en cadena de la polimerasa con transcriptasa inversa (RT-PCR). Sin embargo, esta prueba presenta algunas limitaciones como el alto costo, la necesidad de procesamiento por personal especializado, en un laboratorio con medidas de bioseguridad, la posibilidad inicial de falsos negativos y la tendencia a negativizarse conforme transcurre la enfermedad. Asimismo, existen pruebas basadas en la detección de anticuerpos, principalmente inmunoglobulinas (Ig) M y G. Estas pruebas podrían usarse en la comunidad, no requieren personal altamente calificado ni condiciones estrictas de operación como en caso de las pruebas de RT-PCR. Sin embargo, pueden pasar algunos días desde el inicio de la infección hasta que se produzcan anticuerpos detectables. La utilización complementaria de ambas pruebas podría mejorar la identificación correcta de pacientes con COVID-19, incluyendo a los pacientes asintomáticos o con enfermedad leve, contribuyendo a disminuir su propagación. OBJETIVO: Describir la evidencia científica disponible sobre la utilidad del uso complementario de pruebas moleculares y de detección de anticuerpos para mejorar el diagnóstico de sospechosos de COVID-19. MÉTODO: Búsqueda sistemática de estudios en idioma español o inglés publicados entre el 01 de diciembre de 2019 y el 04 de abril de 2020 en Medline, Cochrane Central Register of Controlled Trials (CENTRAL), MedRxiv, Chinese Clinical Trial Registry (CCTR), y LILACS, complementada con una búsqueda de literatura gris en Google Scholar. RESULTADOS: Se incluyeron 06 estudios que respondieron a la pregunta PICO de interés Tres estudios evaluaron la variación de sensibilidad de diferentes pruebas para el diagnóstico de COVID-19 según los días transcurridos desde el inicio de síntomas. Estos estudios coinciden en observar mayor sensibilidad de las pruebas de RT-PCR durante los primeros siete días del inicio de síntomas (rango: 66,7% a 100%), en comparación con las pruebas de detección de anticuerpos totales (rango: 38,3% a 64,1%), IgG (rango: 19,1% a 53,8%) o IgM (rango: 23,0% a 33,3%). En el intervalo mayor de tiempo de medición de los estudios considerando el inicio de síntomas (más de 15 días), se observó una reversión de la tendencia, con una mayor sensibilidad de la prueba de anticuerpos totales (100% en dos estudios), IgM (rango: 52,2% a 96,7%) e IgG (rango: 79,8% a 93,3%), en comparación con las pruebas de RT-PCR (rango: 13% a 70,7%). Un estudio comparó la disminución de sensibilidad de la prueba de RT-PCR según el tipo de muestra, observando que en las muestras obtenidas de hisopado nasofaríngeo la disminución de sensibilidad fue más acentuada (desde 69,2% a los 7 días, hasta 13% a más de 15 días), en comparación a las muestras de esputo (desde 92,3% a los 7 días, hasta 60,8% a más de 15 días). Un estudio observó que la aplicación de una regla basada en realizar una prueba de detección de anticuerpos a todos los casos negativos según RT-PCR, incrementó la sensibilidad diagnóstica desde un 51,9% hasta un 98,6%, reduciendo el porcentaje de falsos negativos. CONCLUSIONES: Se observó mayor positividad de las pruebas de RT-PCR durante los primeros días del inicio de síntomas, comparado con las pruebas de detección de anticuerpos. Conforme transcurre la enfermedad, la tendencia se revierte, mostrando las pruebas de detección de anticuerpos IgG/IgM una mayor sensibilidad en comparación con las pruebas de RT-PCR. La reducción de la positividad en las pruebas de RT-PCR conforme transcurre la enfermedad, es más acentuada en muestras de hisopado faríngeo, en comparación con muestras de esputo. La aplicación de una regla basada en realizar una prueba de detección de anticuerpos a todos los casos negativos según RT-PCR, incrementa la sensibilidad desde un 51,9% hasta un 98,6%, reduciendo el porcentaje de falsos negativos. Los hallazgos de la presente revisión apoyan el uso complementario de pruebas de RT-PCR y de detección de anticuerpos para el diagnóstico de pacientes con COVID-19.(AU)

Epitope of dengue virus E protein detect human antibodies associated with mild disease: a potential peptide for vaccine development

ABSTRACT The antigenic potential of seven immunogenic peptides of the dengue virus was evaluated in the sera of patients with dengue confirmed by IgM/IgG serology. Antibodies IgM and IgG against dengue virus peptides were analyzed by ELISA in 31 dengue sero-positive and 20 sero-negative patients. The P5 peptide showed significant IgG immunoreactivity mostly in the sera of patients with dengue without warning signs in comparison with patients with dengue with warning signs, correlating with mild disease. This finding suggests that the low antibody response against P5 epitope could be a risk factor for higher susceptibility to dengue virus infection with warning signs, and that P5 could be a potential antigen for vaccine development.

Susceptibility of the elderly to SARS-COV-2 infection: ace-2 overexpression, shedding, and antibody-dependent enhancement (ADE)

The world is currently facing a serious SARS-CoV-2 infection pandemic. </mac_aq>This virus is a new isolate of coronavirus, and the current infection crisis has surpassed the SARS and MERS epidemics</mac_aq> that occurred in 2002 and 2013, respectively. SARS-CoV-2 has currently infected more than 142,000 people, causing </mac_aq>5,000 deaths and spreading across more than 130 </mac_aq>countries worldwide. The spreading capacity of the virus clearly demonstrates the potential threat </mac_aq>of respiratory viruses to human health, thereby reiterating to the governments around the world that preventive </mac_aq>health policies and scientific research are pivotal to overcoming the crisis. Coronavirus disease (COVID-19) causes flu-like symptoms in most cases. However, approximately 15% of the patients need hospitalization, and 5% require assisted ventilation, depending on the cohorts studied. What is intriguing, however, is the higher susceptibility of the elderly, especially individuals who are older than 60 years of age, and have comorbidities, including hypertension, diabetes, and heart disease. In fact, the death rate in this group may be up to 10-12%. Interestingly, children are somehow less susceptible and are not considered as a risk group. Therefore, in this review, we discuss some possible molecular and cellular mechanisms by virtue of which the elderly subjects may be more susceptible to severe COVID-19. Toward this, we raise two main </mac_aq>points, i) increased ACE-2 expression in pulmonary and heart tissues in users of chronic angiotensin 1 </mac_aq>receptor (AT1R) blockers; and ii) antibody-dependent enhancement (ADE) after previous exposure to other circulating coronaviruses. We believe that these points are pivotal for a better understanding of the pathogenesis of severe COVID-19, and must be carefully addressed by physicians and scientists in the field.

Human B1 Cells are the Main Blood Group A-Specific B Cells That Have a Moderate Correlation With Anti-A Antibody Titer

BACKGROUND: Anti-carbohydrate antibody responses, including those of anti-blood group ABO antibodies, are yet to be thoroughly studied in humans. Because anti-ABO antibody-mediated rejection is a key hurdle in ABO-incompatible transplantation, it is important to understand the cellular mechanism of anti-ABO responses. We aimed to identify the main human B cell subsets that produce anti-ABO antibodies by analyzing the correlation between B cell subsets and anti-ABO antibody titers. METHODS: Blood group A-binding B cells were analyzed in peritoneal fluid and peripheral blood samples from 43 patients undergoing peritoneal dialysis and 18 healthy volunteers with blood group B or O. The correlation between each blood group A-specific B cell subset and anti-A antibody titer was then analyzed using Pearson's correlation analysis. RESULTS: Blood group A-binding B cells were enriched in CD27⁺CD43⁺CD1c− B1, CD5⁺ B1, CD11b⁺ B1, and CD27⁺CD43⁺CD1c+ marginal zone-B1 cells in peripheral blood. Blood group A-specific B1 cells (P=0.029 and R=0.356 for IgM; P=0.049 and R=0.325 for IgG) and marginal zone-B1 cells (P=0.011 and R=0.410 for IgM) were positively correlated with anti-A antibody titer. Further analysis of peritoneal B cells confirmed B1 cell enrichment in the peritoneal cavity but showed no difference in blood group A-specific B1 cell enrichment between the peritoneal cavity and peripheral blood. CONCLUSIONS: Human B1 cells are the key blood group A-specific B cells that have a moderate correlation with anti-A antibody titer and therefore constitute a potential therapeutic target for successful ABO-incompatible transplantation.

Sequential battery of COVID-19 testing to maximize negative predictive value before surgeries / Bateria sequencial de testes para COVID-19 para maximizar o valor preditivo negativo antes de operações

ABSTRACT SARS-CoV-2 is a novel virus which has proven to be highly contagious. Specific viral dynamics and immune response to the virus are yet to be fully defined and determining the sensitivity and specificity of the available testing methods is still a work in progress. This study examines the published information on the testing methods, and finds that yield of COVID-19 tests changes with specimen types and with time through course of illness. We propose a sequential battery of testing consisting of an epidemiologic survey, RT-PCR tests, serologic tests and chest CT on surgical candidates which may increase the negative predictive value, and facilitate surgical procedures.

RESUMO O SARS-CoV-2 é um novo vírus que provou ser altamente contagioso. A dinâmica viral específica e a resposta imunológica ao vírus ainda não foram totalmente definidas e a determinação da sensibilidade e especificidade dos métodos de teste disponíveis ainda está em andamento. Este estudo examina as informações publicadas sobre os métodos de testagem e conclui que o rendimento dos testes COVID-19 muda de acordo com o tipo de amostra e com o tempo de progressão da doença. Propomos uma bateria sequencial de testes, que consiste em um levantamento epidemiológico, testes de RT-PCR, testes sorológicos e tomografia computadorizada de tórax em candidatos a cirurgia, que podem aumentar o valor preditivo negativo e facilitar procedimentos cirúrgicos.

Obtención de una versión IgG1 de ratón del rituximab para detectar la molécula CD20 humana / Obtaining a mouse IgG1 version of rituximab to detect the human CD20 molecule

Introducción: El rituximab, anticuerpo quimérico que reconoce la molécula CD20 humana, se ha utilizado en el tratamiento de diversos trastornos linfoproliferativos de células B. Para la selección de los potenciales beneficiarios del tratamiento con rituximab se han desarrollado técnicas que, mediante el uso de anticuerpos monoclonales, detectan la presencia del CD20 en los linfocitos de estos pacientes. Objetivo: Obtener y caracterizar un anticuerpo recombinante IgG1 de ratón específico para la molécula CD20 humana, que contenga las regiones variables del anticuerpo rituximab. Métodos: Para la expresión estable del anticuerpo recombinante se empleó la transducción lentiviral de células de embrión de riñón humano (HEK293). La caracterización inmunoquímica del anticuerpo se realizó por la técnica de Western Blot y su capacidad de reconocimiento de la molécula CD20 humana se evaluó por citometría de flujo e inmunohistoquímica. Resultados: Se obtuvo el anticuerpo 1F5 que reconoce, por citometría de flujo, la molécula CD20 en líneas celulares humanas de origen linfoide, así como en células de sangre periférica de humanos sanos y pacientes con trstornos linfoproliferativos de células B. Sin embargo, la técnica de inmunohistoquímica solo permitió detectar con este anticuerpo la molécula CD20 en tejidos frescos, no así en los embebidos en parafina. Conclusiones: Este trabajo sugiere las potencialidades del uso del anticuerpo 1F5 para las mediciones de la expresión de CD20 por citometría de flujo en pacientes con leucemias B o linfomas B avanzados en fase de leucemización. Esto complementaría los estudios para la selección apropiada de pacientes para el tratamiento con el rituximab(AU)

Introduction: Rituximab, chimeric antibody specific for human CD20 molecule, has been widely used in the treatment of several B-cell linfoproliferative disorders. For the selection of patients with the greatest potential to benefit from the therapy with rituximab, a number of techniques using monoclonal antibodies have been developed to detect the CD20 molecule. Objective: To obtain and to characterize a mouse IgG1 recombinant antibody, specific for human CD20, that contains the variable regions of rituximab. Methods: The lentiviral transduction of human embryonic kidney cells (HEK293) was used for the stable expression of the recombinant antibody. The immunochemical characterization of the antibody was performed by Western Blot and the recognition of CD20 was evaluated by immunohistochemistry and flow cytometry. Results: We generated the antibody 1F5, able to recognize by flow cytometry the CD20 molecule expressed on lymphoid human cell lines, as well as peripheral blood mononuclear cells from healthy donors and patients with B-cell lymphoproliferative disorders. However, 1F5 antibody detected the CD20 molecule on fresh tissues, but not on formalin-fixed paraffin embedded tissues,by immunohistochemistry. Conclusions: This work suggests the potential use of 1F5 antibody for the measurement of CD20 expression by flow cytometry in patients with B-cell leukemias or B-cell lymphomas in phase of leukemization. This could complement the studies to ensure the appropriate selection of patients for the treatment with rituximab(AU)

Characteristic profile of antibody responses to PPD, ESAT-6, and CFP-10 of Mycobacterium tuberculosis in pulmonary tuberculosis suspected cases in Surabaya, Indonesia

Abstract Accurate and rapid diagnostic tools are important aspects of managing tuberculosis (TB) cases appropriately. However, the sensitivity and specificity of diagnostic kits based on immune response such as the tuberculin skin test (TST) and interferon gamma release assay (IGRA) are still debated. Thus, the exploration and assessment of specific biomarker-targeted antibodies are needed for the development of an accurate and rapid diagnostic tool. The present study was conducted in patients with a respiratory problem suspected to be TB at Dr. Soetomo Hospital, Surabaya, Indonesia. Among 102 patients tested by GeneXpert and AFB, 59 serum samples were from cases retrospectively determined to have active TB. A total of 102 serum of healthy controls (HC) was also collected. The PPD antigen and the recombinant CFP-10 and ESAT-6 proteins were prepared. Antibody responses against these proteins were evaluated by ELISA. All samples were also screened for the possibility of Mycobacterium avium-intracellulare complex (MAC) infection using Capilla MaC kit. The results showed that TB patients had a significantly higher concentration of IgG antibody in response to PPD than the HC. In addition, the receiver operating characteristic (ROC) curve analysis showed that PPD was acceptable for diagnostic purposes with an AUC value of 0.835 (95% CI 0.770-0.900, p < 0.0001). However, ESAT-6 and CFP-10 had low AUCs, and 32 samples from both groups showed a low concentration of IgA antibody against all antigens. The MAC detection results also showed that the concentration of IgA in the HC group was the highest. The current results indicate that PPD is a better antigen for antibody-based detection of TB than ESAT-6 and CFP-10. Based on the MAC detection assay, 53 people in the HC group were probably infected with rapidly growing nontuberculous mycobacteria (NTM), although antibody response to PPD was low.

Nucleoprotein vaccine induces cross-protective cytotoxic T lymphocytes against both lineages of influenza B virus

PURPOSE: The influenza B virus diverges into two antigenically distinct lineages: B/Yamagata and B/Victoria. Influenza B is the dominant circulating virus during some influenza seasons, and recent data demonstrated that influenza A and B infection similarly cause severe clinical symptoms in hospitalized patients. Nucleoprotein (NP) is a good target for a universal influenza vaccine. This study investigated whether NP epitope variation within two lineages affects the dominant cytotoxic T lymphocyte (CTL) responses induced by vaccination and the resultant protective immunity. MATERIALS AND METHODS: The NP of B/Yamagata/16/1988, the representative strain of the Yamagata lineage, includes a dominant CTL epitope, FSPIRITFL, while B/Shangdong/7/1997 from the Victoria lineage has one amino acid difference in this sequence, FSPIRVTFL. Two recombinant replication-deficient adenovirus (rAd)-vectored vaccines expressing either NP were prepared (rAd/B-NP(I) and rAd/B-NP(V), respectively) and administered to BALB/c mice intranasally. To examine the efficacy of vaccination, antibody responses, CTL responses, and morbidity/mortality after challenge were measured. RESULTS: Both vaccines induce similar antibody and CD8 T-cell responses cross-reacting to both epitopes, and also confer cross-protection against both lineages regardless of amino acid difference. CONCLUSION: The rAd-vectored vaccine expressing the NP could be developed as universal influenza B vaccine which provides broader protection.

A phase 1/2a, dose-escalation, safety and preliminary efficacy study of oral therapeutic vaccine in subjects with cervical intraepithelial neoplasia 3 / 부인종양

OBJECTIVE: Persistent infection of HPV increases the chance of carcinoma in situ of cervix through stages of cervical intraepithelial neoplasia (CIN) 1, 2, and 3, and finally progresses into cervical cancer. We aimed to explore the safety and efficacy of BLS-M07 which is orally administered agent expressing human papillomavirus (HPV) 16 E7 antigen on the surface of Lactobacillus casei in patients with CIN 3. METHODS: Patients with CIN 3 were recruited in our clinical trial. Reid Colposcopic Index (RCI) grading and serum HPV16 E7 specific antibody production were used to evaluate efficacy of BLS-M07. In phase 1, BLS-M07 was administered orally, 5 times a week, on weeks 1, 2, 4, and 8 with dosages of 500 mg, 1,000 mg, and 1,500 mg. In phase 2a, patients were treated with 1,000 mg. The primary endpoints were the safety and the pathologic regression on colposcopic biopsy. RESULTS: Nineteen patients were enrolled in the CIN 3 cohort. In phase 1, no patients experienced dose limiting toxicity. No grade 3 or 4 treatment-related adverse events or deaths were observed. At 16 weeks after treatment, RCI grading was improved and serum HPV16 E7 specific antibody production increased (p<0.05). Six of 8 (75%) patients with CIN 3 were cured in phase 2a. CONCLUSIONS: Oral immunization with BLS-M07 increases production of serum HPV16 E7 specific antibody which induces protective humoral immunity. The safety of this oral vaccine was proved and could be a competitive non-surgical therapeutic agent of CIN 3. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02195089

Curcumin Elevates T(FH) Cells and Germinal Center B Cell Response for Antibody Production in Mice

Curcumin is a natural product extracted from Curcuma longa. It has been reported as a potent antioxidant and anti-inflammatory compound. Previous studies have demonstrated that curcumin suppresses pro-inflammatory cytokine production via inhibition of NF-κB in macrophages. However, its role in adaptive immune cells such as T cells, in vivo, has not clearly been elucidated. Here, we examined the effects of curcumin in T follicular helper (T(FH)) cells and on Ab production during NP-ovalbumin immunization in mice. The results revealed that curcumin administered daily significantly increased CXCR5⁺B-cell lymphoma 6⁺ T(FH) cells and CD95⁺GL-7⁺ germinal center (GC) B cells in draining lymph nodes. In addition, curcumin treatment in mice induced total Ab production as well as high affinity IgG1 and IgG2b Ab production. Collectively, these results suggest that curcumin has positive regulatory roles in T(FH) cell functions and GC responses. Thus, this could be an advantageous supplement to enhance humoral immunity against infectious diseases and cancer.

Advances in Serological Diagnosis of Taenia solium Neurocysticercosis in Korea

Cysticercosis, a parasitic disease caused by Taenia solium metacestode (TsM), has a major global public health impact in terms of disability-adjusted life years. The parasite preferentially infects subcutaneous tissue, but may invade the central nervous system, resulting in neurocysticercosis (NC). NC is an important neglected tropical disease and an emerging disease in industrialized countries due to immigration from endemic areas. The prevalence of taeniasis in Korea declined from 0.3%–12.7% during the 1970s to below 0.02% since the 2000s. A survey conducted from 1993 to 2006 revealed that the percentage of tested samples with high levels of specific anti-TsM antibody declined from 8.3% to 2.2%, suggesting the continuing occurrence of NC in Korea. Modern imaging modalities have substantially improved the diagnostic accuracy of NC, and recent advances in the molecular biochemical characterization of the TsM cyst fluid proteome also significantly strengthened NC serodiagnosis. Two glycoproteins of 150 and 120 kDa that induce strong antibody responses against sera from patients with active-stage NC have been elucidated. The 150 kDa protein showed hydrophobic-ligand binding activities and might be critically involved in the acquisition of host-derived lipid molecules. Fasciclin and endophilin B1, both of which play roles in the homeostatic functions of TsM, showed fairly high antibody responses against calcified NC cases. NC is now controllable and manageable. Further studies should focus on controlling late-onset intractable seizures and serological diagnosis of NC patients infected with few worms. This article briefly overviews diagnostic approaches and discusses current issues relating to NC serodiagnosis.