Co-administration of flagellin augments immune responses to inactivated foot-and-mouth disease virus (FMDV) antigen

Foot-and-mouth disease virus (FMDV) is one of the most contagious animal virus known that affects livestock health and production. This study aimed to investigate the effect of flagellin, a toll-like receptor 5 agonist, on the immune responses to inactivated FMDV antigen in guinea pig model. Our results showed that the co-administration of flagellin with FMDV antigen through intradermal route induces earlier and higher anti-FMDV neutralizing antibody responses as compared to FMDV antigen alone. Both IgG1 and IgG2 antibody-isotype responses were enhanced, but the IgG1/IgG2 ratios were relatively low, indicative of TH1 type of immune activation. On live viral challenge, flagellin + FMDV immunized guinea pigs showed 70% (7 out of 10) protection rate as compared to 40% (4 out of 10) in FMDV alone immunized guinea pigs. The results demonstrate that the co-administration of flagellin augments immune responses (preferably TH1 type) and protective efficacy against FMDV in guinea pigs.