Efficacy of a Self-Vaccination Strategy for Influenza A Virus, Mycoplasma hyopneumoniae, Erysipelothrix rhusiopathiae, and Lawsonia intracellularis in Swine

Abstract

Background/Objectives: Environmental enrichment (EE) devices are required in various countries and markets to promote animal welfare, with dual-purpose devices more likely to encourage adoption. We developed an EE device that allows pigs to self-administer liquids, designed to align with natural and play behaviors, and utilized a maternal pheromone (MP) to attract pigs to the device. This study aimed to evaluate the efficacy of this device in delivering vaccines for Erysipelas, Ileitis, Mycoplasma, and Influenza to growing pigs. Methods: Pigs were assigned to three treatments groups: Control (unvaccinated), Hand-Vaccinated (via oral gavage or intramuscular injection), and Self-Vaccinated using the EE device. Baseline samples were collected to determine initial antibody status, and serum and oral fluids' IgG and IgA levels were measured post-vaccination to assess immune response. Four studies were conducted with 36 pigs (12 per treatment) over a 49-day period. Results: Self-vaccination pigs receiving the avirulent live Erysipelas vaccine developed oral and serum antibodies comparable to Hand-Vaccinated pigs. Pigs self-administering the avirulent live Lawsonia intracelluaris vaccine developed oral fluid antibodies. In contrast, pigs who received Mycoplasma or Influenza vaccines through self-vaccination exhibited significantly lower antibody levels compared to the Hand-Vaccinated group. Conclusions: These findings demonstrated that self-vaccination using EE devices for the oral administration of avirulent live vaccines offers benefits such as reduced labor and improved animal welfare. However, killed vaccines did not elicit sufficient antibody responses, suggesting the need for modified vaccine formulations or administration strategies to improve self-vaccination efficacy.

Keywords: behavior; environmental enrichment; pigs; self-vaccination.

Figure 1

(A) Example of a pig self-vaccinating using the EE device. (B) Pigs exposed to EE device. The blue dye was added to the vaccine to identify that the pig had been exposed to the vaccine.

Figure 2

The effect of MP on spray occurrence (total sprays over 5 h) pig interaction with the EE device. The frequency of spray occurrence was significantly (p < 0.05) higher in the MP treatment group compared to Control. Data were collected over 24 h periods: one day without MP (Control), and another day with MP. An asterisk (*) indicates a significant difference (p < 0.05).

Figure 3

Time course of IgG antibody (data transformed) development for Trial A—MHP. Control group received no vaccine, Hand-Vaccinated received IM, and Self-Vaccinated group used the EE device. (A)—Serum IgG levels and (B)—oral fluid IgG levels. Box-plot illustrates the distribution of IgG levels across the groups. Different letters (a, b) indicate statistically significant differences between groups at each time point (Tukey–Kramer post hoc test, p < 0.05).

Figure 4

Time course of IgG antibody development for Trial B—IAV. Control group received no vaccine, Hand-Vaccinated received IM, and Self-Vaccinated group used the EE device. (A)—Serum IgA levels, (B)—serum TAB, and (C)—oral fluid IgA. Box-plot illustrates the distribution of IgG levels across the groups. Different letters (a, b) indicate statistically significant differences between groups at each time point (Tukey–Kramer post hoc test, p < 0.05).

Figure 5

Time course of IgG antibody (data transformed—serum) development for Trial C—ERY. Control group received no vaccine, Hand-Vaccinated received IM, and Self-Vaccinated group used the EE device. (A)—serum IgG levels and (B)—oral fluid IgG levels. Box-plot illustrates the distribution of IgG levels across the groups. Different letters (a, b, and c) indicate statistically significant differences between groups at each time point (Tukey–Kramer post hoc test, p < 0.05).

Figure 6

Time course of IgG antibody development for Trial D, LAW. Control group received no vaccine, Hand-Vaccinated group received IM, and Self-Vaccinated group used the EE device. (A)—Serum IgA levels, (B)—serum TAB, and (C)—oral fluid IgA. Box-plot illustrates the distribution of IgG levels across the groups. Different letters (a, b) indicate statistically significant differences between groups at each time point (Tukey–Kramer post hoc test, p < 0.05).