Humoral immune response after different SARS-CoV-2 vaccination regimens.

BACKGROUND: The humoral immune response after primary immunisation with a SARS-CoV-2 vector vaccine (AstraZeneca AZD1222, ChAdOx1 nCoV-19, Vaxzevria) followed by an mRNA vaccine boost (Pfizer/BioNTech, BNT162b2; Moderna, m-1273) was examined and compared with the antibody response after homologous vaccination schemes (AZD1222/AZD1222 or BNT162b2/BNT162b2). METHODS: Sera from 59 vaccinees were tested for anti-SARS-CoV-2 immunoglobulin G (IgG) and virus-neutralising antibodies (VNA) with three IgG assays based on (parts of) the SARS-CoV-2 spike (S)-protein as antigen, an IgG immunoblot (additionally contains the SARS-CoV-2 nucleoprotein (NP) as an antigen), a surrogate neutralisation test (sVNT), and a Vero-cell-based virus-neutralisation test (cVNT) with the B.1.1.7 variant of concern (VOC; alpha) as antigen. Investigation was done before and after heterologous (n = 30 and 42) or homologous booster vaccination (AZD1222/AZD1222, n = 8/9; BNT162b2/BNT162b2, n = 8/8). After the second immunisation, a subgroup of 26 age- and gender-matched sera (AZD1222/mRNA, n = 9; AZD1222/AZD1222, n = 9; BNT162b2/BNT162b2, n = 8) was also tested for VNA against VOC B.1.617.2 (delta) in the cVNT. The strength of IgG binding to separate SARS-CoV-2 antigens was measured by avidity. RESULTS: After the first vaccination, the prevalence of IgG directed against the (trimeric) SARS-CoV-2 S-protein and its receptor binding domain (RBD) varied from 55-95% (AZD1222) to 100% (BNT162b2), depending on the vaccine regimen and the SARS-CoV-2 antigen used. The booster vaccination resulted in 100% seroconversion and the occurrence of highly avid IgG, which is directed against the S-protein subunit 1 and the RBD, as well as VNA against VOC B.1.1.7, while anti-NP IgGs were not detected. The results of the three anti-SARS-CoV-2 IgG tests showed an excellent correlation to the VNA titres against this VOC. The agreement of cVNT and sVNT results was good. However, the sVNT seems to overestimate non- and weak B.1.1.7-neutralising titres. The anti-SARS-CoV-2 IgG concentrations and the B.1.1.7-neutralising titres were significantly higher after heterologous vaccination compared to the homologous AZD1222 scheme. If VOC B.1.617.2 was used as antigen, significantly lower VNA titres were measured in the cVNT, and three (33.3%) vector vaccine recipients had a VNA titre < 1:10. CONCLUSIONS: Heterologous SARS-CoV-2 vaccination leads to a strong antibody response with anti-SARS-CoV-2 IgG concentrations and VNA titres at a level comparable to that of a homologous BNT162b2 vaccination scheme. Irrespective of the chosen immunisation regime, highly avid IgG antibodies can be detected just 2 weeks after the second vaccine dose indicating the development of a robust humoral immunity. The reduction in the VNA titre against VOC B.1.617.2 observed in the subgroup of 26 individuals is remarkable and confirms the immune escape of the delta variant.

Evaluation of Three Vaccination Schemes Against Clostridium perfringens Alpha Toxin and Their Effects on the Performance, Level of Intestinal Lesions, and Serum Antibody Titers in Broilers.

The objective of the trial was to evaluate three vaccination schemes against Clostridium perfringens (CP) alpha-toxoid through drinking water to determine if they can protect against clinical signs of necrotic enteritis and coccidiosis in broiler chickens. Three hundred 1-day-old Cobb 500 male chicks were used in 4 treatments with 10 repetitions. Each group received 1 of the following treatments over the course of 29 days: T1, no vaccination; T2, vaccination on Day 1; T3, vaccination on Day 7; and T4, vaccination on Days 7 and 17. The birds were vaccinated with inactivated CP toxoid type A, administered via drinking water. During the first 14 days, a high-protein diet (27%) consisting of corn, soy, and fish meal was fed. On Day 14 Eimeria acervulina (EA), Eimeria maxima (EMx), Eimeria tenella (ET), Eimeria necatrix, and Eimeria brunetti were used in a coccidial challenge. The field isolate CP type A was then inoculated on Days 18, 19, and 20. Ten birds were slaughtered by treatment to obtain serology samples for antibody titers and intestine samples for CP and Eimeria lesion score and gut integrity indicators. Productive performance was assessed using complete randomized design and compared statistically using the Tukey test, whereas intestinal integrity variables and antibodies against CP alpha toxin were assessed using a Kruskal-Wallis nonparametric method. The results revealed that the treatments had an effect on productive performance (P < 0.05); T3 had better body weight and weight gain than T1. In terms of lesion score at Day 21, T4 had a lower lesion score by EA, EMx, and ET than T1. Cell desquamation in T2 was lower than in T4, and excess mucus (EM) in T1 was the worst in gut integrity indicators at Day 21. On the other hand, T2 had more EM than T3 and T4 at Day 25. In the measurement of antibodies, no statistical differences (P > 0.05) were found. These findings indicate that vaccination on Day 7 (T3) outperformed double vaccination on Days 7 and 17 (T4) and single on Day 1 (T2), in terms of productive performance, gut integrity, and lesion scores; and on the last day of the experiment T3 had the best performance in immunology response.

Evaluación de tres esquemas de vacunación contra la toxina alfa de Clostridium perfringens y sus efectos sobre el rendimiento, el nivel de lesiones intestinales y los títulos de anticuerpos séricos en pollos de engorde. El objetivo del ensayo fue evaluar tres programas de vacunación contra Clostridium perfringens (CP) con un alfa-toxoide a través del agua de bebida para determinar si protegían contra signos clínicos de enteritis necrótica y coccidiosis en pollos de engorde. Para ello se emplearon 300 pollitos machos Cobb 500 de un día de edad, distribuidos en 4 tratamientos con 10 repeticiones. Cada grupo recibió, durante 29 días, uno de los siguientes tratamientos: T1: sin vacunación; T2: vacunación en el día uno; T3: vacunación en el día siete y T4, vacunación en los días siete y 17. Las aves fueron vacunadas con toxoide inactivado de C. perfringens tipo A, que se administró en el agua de bebida. Durante los primeros 14 días se alimentó con una dieta alta en proteína (27%) que consistía en maíz, soya y harina de pescado. El desafío coccidial se realizó en el día 14 con Eimeria acervulina (EA), Eimeria maxima (EMx), Eimeria tenella (ET), Eimeria necatrix and Eimeria brunetti. Posteriormente, en los días 18, 19 y 20 se inoculó una cepa aislada de campo de C. perfringens tipo A. Se sacrificaron diez aves por tratamiento para obtener muestras de sueros para determinar los títulos de anticuerpos y muestras de intestino para determinar la puntuación de lesiones por C. perfringens, por Eimeria y los indicadores de integridad intestinal. El comportamiento productivo se analizó bajo un diseño completamente al azar (DCA) y la comparación estadística se realizó mediante la prueba de Tukey, mientras que para las variables de integridad intestinal y los títulos de anticuerpos contra alfa toxina de C. perfringens se utilizó el método no paramétrico Kruskal-Wallis. Los resultados mostraron que el comportamiento productivo fue influenciado por los tratamientos (P < 0.05); el tratamiento T3 mostró el mejor peso corporal y ganancia de peso en comparación con el tratamiento T1. Con relación al puntaje de lesiones en el día 21, el tratamiento T4 tuvo el menor puntaje de lesiones por E. acervulina, E. maxima y E. tenella en comparación con el tratamiento T1. La descamación celular en el tratamiento T2 fue menor que en el T4 y el exceso de moco en el tratamiento T1 fue peor entre los indicadores de integridad intestinal en el día 21. Por otro lado, el tratamiento T2 tenía más exceso de moco en comparación con los tratamientos T3 y T4 en el día 25. No se encontraron diferencias estadísticas (P > 0.05) en la medición de títulos de anticuerpos. Estos hallazgos indican que la vacunación en el día siete (T3) superó a la vacunación doble en los días 7 y 17 (T4) y única en el día uno (T2), en términos de rendimiento productivo, integridad intestinal y puntajes de lesiones, además en el último día del experimento, el tratamiento T3 tuvo el mejor desempeño en la respuesta inmunológica.

Clinical and Virological Features of Patients Hospitalized with Different Types of COVID-19 Vaccination in Mexico City.

Coronavirus disease 2019 (COVID-19) vaccines effectively protect against severe disease and death. However, the impact of the vaccine used, viral variants, and host factors on disease severity remain poorly understood. This work aimed to compare COVID-19 clinical presentations and outcomes in vaccinated and unvaccinated patients in Mexico City. From March to September 2021, clinical, demographic characteristics, and viral variants were obtained from 1014 individuals with a documented SARS-CoV-2 infection. We compared unvaccinated, partially vaccinated, and fully vaccinated patients, stratifying by age groups. We also fitted multivariate statistical models to evaluate the impact of vaccination status, SARS-CoV-2 lineages, vaccine types, and clinical parameters. Most hospitalized patients were unvaccinated. In patients over 61 years old, mortality was significantly higher in unvaccinated compared to fully vaccinated individuals. In patients aged 31 to 60 years, vaccinated patients were more likely to be outpatients (46%) than unvaccinated individuals (6.1%). We found immune disease and age above 61 years old to be risk factors, while full vaccination was found to be the most protective factor against in-hospital death. This study suggests that vaccination is essential to reduce mortality in a comorbid population such as that of Mexico.