Th1-biased immunoadjuvant effect of the recombinant B subunit of anEscherichia coli heat-labile enterotoxin on an inactivated porcinereproductive and respiratory syndrome virus antigen via intranasal immunization inmice

摘要

Porcine reproductive and respiratory syndrome (PRRS) is one of the major swine diseasesresponsible for a significant challenge in the global swine industry. The current PRRSinactivated vaccine only confers limited protection against PRRSV. Thus, using anappropriate adjuvant via a suitable administration route may help improve vaccineefficacy. In this study, the recombinant B subunit of the heat-labile enterotoxin rLTB, was highly expressed in , through high-density fermentation. rLTB intranasal adjuvantproperties were evaluated on an inactivated PRRS antigen in mice. Compared to the groupimmunized with solely PRRS antigen, a dose of 50 g rLTB remarkablyraised antigen-specific IgA antibodies at mucosal sites, and increased serum IgGantibodies, preferentially the IgG2a and IgG2b subclasses. Further, rLTB induced increasesin Th1- (IFN-γ and IL-12) and Th17 (IL-6) cytokine profiles, but had little effect on Th2cytokine profiles (IL-4 and IL-10). Moreover, there were no overt toxicities associatedwith intranasal rLTB administration. Our data provide evidence that the rLTB produced by fermentation portrays low toxicity, and its intranasaladjuvant effect involves immune system modulation to a Th1 profile.