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Poult Sci ; 101(2): 101592, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34922043

RESUMO

Gram-positive Clostridium perfringens type G, the causative agent of necrotic enteritis (NE), has gained more attention in the poultry industry due to governmental restrictions on the use of growth-promoting antibiotics in poultry feed. Our previous work has proved that regulated delayed lysis Salmonella vaccines delivering a plasmid encoding an operon fusion of the nontoxic C-terminal adhesive part of alpha toxin and a GST-NetB toxin fusion were able to elicit significant protective immunity in broilers against C. perfringens challenge. We recently improved our S. Typhimurium antigen delivery vaccine strain by integrating a rhamnose-regulated O-antigen synthesis gene enabling a triple-sugar regulation system to control virulence, antigen-synthesis and lysis in vivo traits. The strain also includes a ΔsifA mutation that was previously shown to increase the immunogenicity of and level of protective immunity induced by Salmonella vectored influenza and Eimeria antigens. The new antigen-delivery vaccine vector system confers on the vaccine strain a safe profile and improved protection against C. perfringens challenge. The strain with the triple-sugar regulation system delivering a regulated lysis plasmid pG8R220 encoding the PlcC and GST-NetB antigens protected chickens at a similar level observed in antibiotic-treated chickens. Feed conversion and growth performance were also similar to antibiotic-treated chickens. These studies made use of a severe C. perfringens challenge with lesion formation and mortality enhanced by pre-exposure to Eimeria maxima oocysts. The vaccine achieved effectiveness through three different immunization routes, oral, spray and in drinking water. The vaccine has a potential for application in commercial hatcher and broiler-rearing conditions.


Assuntos
Toxinas Bacterianas , Infecções por Clostridium , Enterite , Doenças das Aves Domésticas , Vacinas contra Salmonella , Animais , Galinhas , Infecções por Clostridium/prevenção & controle , Infecções por Clostridium/veterinária , Clostridium perfringens , Enterite/prevenção & controle , Enterite/veterinária , Necrose/veterinária , Doenças das Aves Domésticas/prevenção & controle , Açúcares
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