Serum concentration of acute phase proteins and cytokines in vaccinated pigs challenged with foot-and-mouth disease virus serotype O

ABSTRACT The present study aimed to investigate the kinetics of acute phase proteins and cytokines in the serum of immunized or naive pigs following infection with a field isolate of foot-and-mouth disease (FMD) virus. Five-month-old SPF pigs were intramuscularly immunized with or without the 146S antigen (7.5 μg per head) purified from FMD virus (O/Andong/SKR/2010) and were subsequently challenged 30 days post-vaccination (dpv) with FMD virus on each footpad. Serum samples were obtained at 28 dpv and on days 1, 3, and 5 post-infection (dpi). At 28 dpv, the serum concentrations of C-reactive protein and tumor necrosis factor alpha (TNF-α) were higher in the immunized pigs compared with the non-immunized control pigs. Upon challenge, the levels of all measured acute phase proteins (i.e., C-reactive protein, major acute phase protein, S-amyloid A, and haptoglobin) plateaued at 1 dpi in the immunized pigs whereas they gradually increased up to 5 dpi in the non-immunized control pigs. Levels of serum TNF-α remained higher in the immunized challenged pigs compared with the non-immunized challenged pigs. The serum concentration of interleukin (IL)-6 in the immunized challenged pigs was undetectable at all time points, but moderately increased upon challenge in the non-immunized challenged pigs. IL-1β was not detected in any of the pigs at any of the observed time points. Collectively, these findings show that the immunized pigs exhibit a rapid serum acute phase protein response following subsequent challenge with the field FMD virus compared with the non-immunized pigs.