RESUMEN
Schistosomiasis is a worldwide parasitic disease. Currently, chemotherapy is the main effective method to treat schistosomiasis; however, it does not prevent reinfection. No effective vaccine is currently available to prevent schistosomiasis. Sj-F1 (GenBank accession number AY261995) is a novel gene that was discovered through screening adult Schistosoma japonicum worm cDNA library with female S. japonicum antigen-immunized sera. Streptococcus gordonii, a normal inhabitant of the human oral cavity, has been a prime candidate in recent investigations toward developing a live oral vaccine vector. One of the approaches for the surface expression of heterologous antigens in S. gordonii is to surface-localize them with the M6 protein from Streptococcus pyogenes. Here, we develop a recombinant S. gordonii strain that expresses the M6-Sj-F1 fusion protein on the bacterial surface. Intranasal immunization in mice with such M6-Sj-F1-expressing S. gordonii bacteria induced strong serum IgG, serum IgA, and saliva IgA against Sj-F1. The results of protective immunity against a challenge with cercariae of S. japonicum showed statistically significant protection following this treatment, with a worm reduction rate of 21.45% and an egg reduction rate of 34.77%. Our data indicate that the described M6-Sj-F1-expressing S. gordonii is highly immunogenic and can partially protect mice from challenge infection with S. japonicum. Intranasal immunization with recombinant S. gordonii may be an alternative to developing a novel S. japonicum vaccine in a safe, effective, and feasible way.
Asunto(s)
Antígenos Helmínticos/inmunología , Portadores de Fármacos , Schistosoma japonicum/inmunología , Esquistosomiasis Japónica/prevención & control , Streptococcus gordonii/genética , Vacunas Sintéticas/inmunología , Administración Oral , Animales , Anticuerpos Antihelmínticos/análisis , Anticuerpos Antihelmínticos/sangre , Antígenos Bacterianos/genética , Antígenos Bacterianos/inmunología , Antígenos Helmínticos/genética , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas Portadoras/genética , Proteínas Portadoras/inmunología , Técnicas de Visualización de Superficie Celular , Modelos Animales de Enfermedad , Femenino , Inmunoglobulina A/análisis , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Ratones , Carga de Parásitos , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Saliva/inmunología , Schistosoma japonicum/genética , Esquistosomiasis Japónica/inmunología , Vacunas Atenuadas/administración & dosificación , Vacunas Atenuadas/genética , Vacunas Atenuadas/inmunología , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/genéticaRESUMEN
Severe corrosion of Mg and Mg alloys is a major issue hindering their wider application in transportation industry, medical implants and aqueous batteries. Previously, no Mg-based material has been found with a significantly lower corrosion rate than that of ultra-high-purity Mg, i.e. 0.25 mm y-1 in concentrated NaCl solution. In this work for the first time, highly corrosion-resistant Mg is found to be accomplishable by Ca micro-alloying, bringing "stainless Mg" closer. The designed Mg-Ca lean alloys possess incredibly low corrosion rates, less than 0.1 mm y-1 in 3.5 wt% NaCl solution, which are significantly lower than that of ultra-high-purity Mg and all Mg alloys reported thus far. The outstanding corrosion resistance is attributed to inhibition of cathodic water reduction kinetics, impurities stabilizing and a protective surface film induced by Ca micro-alloying. Combined with the environmental benignity and economic viability, Ca micro-alloying renders huge feasibility on developing advanced Mg-based materials for diverse applications.