Antibiotic Therapy Does Not Alter the Humoral Response to Vaccination for Porcine Circovirus 2 in Weaned Pigs

Abstract

Recent reports suggest that antibiotic therapy may either reduce or enhance the immune response to various porcine vaccines. Based upon these findings, we asked if antibiotic therapy alters immune cell populations, as measured by flow cytometry and/or vaccine-specific humoral immunity, as measured by sample to positive (S/P) antibody ratios. Here, we investigated the immuno-modulatory effects of enrofloxacin, ceftiofur, and tulathromycin on the immune response to a Mycoplasma hyopneumoniae (M. hyopneumoniae) and porcine circovirus type 2 (PCV-2) combination vaccine in weaned pigs. Maternal antibody likely interfered with the induction of immunity to M. hyopneumoniae. Antibiotic administration did not affect immune cell populations, as assessed by flow cytometry and did not affect the induction of humoral immunity to PCV-2.

Keywords: Pig; antibiotic; vaccine.

Figure 1

Sample to positive (S/P) ratios to Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV-2). Pigs were either unvaccinated (n = 31) or vaccinated with a Mhyo/PCV-2 vaccine (n = 32) prior to weaning. (a,b). For both unvaccinated and vaccinated groups, the Mhyo S/P ratios declined over time. (c). For the PCV-2 unvaccinated groups, the PCV-2 S/P ratio declined over time. (d). For the PCV-2 vaccinated groups, the PCV-2 S/P ratio declined and then rebounded over time. (c,d). For days 21 and 35 the PCV-2 S/P ratio was higher when compared to unvaccinated controls (p < .05, asterisks).

Figure 2

Assessment of PCV-2 S/P ratio over time for weanling pigs administered different antibiotics. There was no difference in PCV-2 S/P ratios when vaccinated pigs (VAX, diagonal bars) were compared to vaccinated pigs administered the three different antibiotics (n = 8 pigs per antibiotic treatment group, solid bars, see legend, each bar represents mean + SEM).