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@#Objective To explore the absorption characteristics of aluminum hydroxide adjuvant with inactivated enterovirus 71(EV71).Methods The morphology,purity and particle size distribution of inactivated EV71 particles were analyzed by transmission electron microscope,size exclusion chromatography HPLC(SEC-HPLC) and dynamic light scatter(DLS),and the morphology of aluminum hydroxide adjuvant nanoparticles was observed by transmission electron microscope.Using inactivated EV71 antigen content(4 000,6 000,8 000,10 000,11 000,12 000,13 000,14 000,20 000,30 000 U/mL),aluminum hydroxide adjuvant concentration [0.35,0.25,0.17,0.085 mg/mL(aluminum content)],adsorption time(0.30 and 120 min),ionic strength(sodium chloride concentration of 0.15,0.75 and 1.25 mol/L)and phosphorus-aluminum molar ratio(P/Al,0.15,0.64,2.08 and 7.87) as variables,the adsorption characteristics of aluminum hydroxide adjuvant with inactivated EV71 antigen were investigated.Results Inactivated EV71 particles mainly existed in the form of intact virus particles with a diameter of about 30 nm;Aluminum hydroxide adjuvant showed the characteristics of nanocrystallization,and the particle size was distributed within 200～700 nm.The inactivated EV71 antigen at the concentration of no more than 11 000 U/mL was completely absorbed by aluminum hydroxide adjuvant of 0.35 mg/mL(aluminum content),and no free antigen was detected in the supernatant;while from 12 000 U/mL,the content of free antigen in the supernatant increased with the increase of antigen content;the inactivated EV71 antigen of 250 U/mL was completely absorbed by various concentrations of aluminum hydroxide adjuvant,and no free antigen was detected in the supernatant;the adsorption effect of aluminum hydroxide adjuvant consistent after incubation for different time,and no free antigen was detected in the supernatant.Under the conditions of single dose of vaccine with aluminum hydroxide content(0.35 mg/mL) and inactivated EV71 antigen content(250 U/mL),sodium chloride ion strength had no effect on the adsorption of inactivated EV71 virus,while phosphate ion concentration significantly effected the adsorption.Conclusion Aluminum hydroxide adjuvant in a single dose of vaccine completely absorbed inactivated EV71 antigen,and group replacement played an important role.
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The bovine viral diarrhea virus (BVDV) infection control should be based on elimination of persistently infected animals and on immunization through vaccination, to prevent fetal infection. However, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. This study evaluated the humoral immune response against homologous and heterologous strains of 7 inactivated BVDV vaccines, in bovines and two experimental models (ovine and guinea pig) which might be used to test candidate vaccines. Vaccines formulated with BVDV Singer, Oregon, NADL, and multivalent, induced seroconversion in the three animal models studied, reaching antibody titres higher than 2. Vaccine containing 125C -genotype 2- only induced a low antibody response in ovine, while VS-115 NCP vaccine was not immunogenic. Furthermore, bovine sera at 60 dpv presented homologous as well as heterologous antibody response, indicating a high degree of cross-reactivity among the strains studied. However, when bovine sera were tested against the Argentine field strain 00-693, they showed the lowest levels of cross-reactivity, suggesting the need of continued surveillance to identify and characterize emerging field BVDV strains. Finally, optimal correlations between bovine-ovine and bovine-guinea pig models were observed, indicating that two alternative species could replace bovines when testing the immunogenicity of BVDV candidate vaccines.
El control del virus de la diarrea viral bovina (VDVB) se basa en la eliminación de animales persistentemente infectados, y la inmunización de hembras para prevenir infecciones fetales. La eficiencia de estas vacunas es variable por su baja inmunogenicidad. Se evaluó la respuesta inmune humoral contra virus homólogos y heterólogos de 7 vacunas experimentales inactivadas del VDVB en bovinos y en dos modelos experimentales (ovinos y cobayos). Las vacunas conteniendo VDVB Singer, Oregon, NADL y polivalentes indujeron seroconversión en los tres modelos y se alcanzaron títulos de anticuerpos mayores de 2. La vacuna con VDVB genotipo 2 VS-115, NCP, no resultó inmunogénica. La vacuna genotipo 2 125C sólo indujo baja respuesta humoral en ovinos, mientras que la VS-115, NCP, no resultó inmunogénica. En bovinos se determinó la respuesta a virus homólogos y heterólogos a 60 dpv, lo que indica un alto grado de inmunidad cruzada entre la mayoría de las cepas estudiadas. Cuando los sueros bovinos fueron ensayados con la cepa de campo de Argentina 00-693, los niveles de reacción cruzada fueron más bajos; esto sugiere la necesidad de una vigilancia epidemiológica sostenida a fin de identificar y caracterizar las cepas emergentes del VDVB. La óptima correlación en el modelo bovino-ovino y bovino-cobayo indica su utilidad para evaluar la inmunogenicidad de vacunas inactivadas de VDVB.