Efficacy and immune response after administration of a booster dose against Mycoplasma hyopneumoniae in the termination phase using an oral vaccine containing the nanostructured silica SBA-15 as an adjuvant

• Grant number: 24/22516-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: June 01, 2025
• End date: April 30, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Pathology
• Principal Investigator: Luís Guilherme de Oliveira
• Grantee: Gabriel Alexandre de Aguiar
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Mycoplasma hyopneumoniae is the etiological agent of Porcine Enzootic Pneumonia (PEP), a chronic disease of the respiratory tract of these animals that leads to a continuous loss of performance of these animals, presenting high morbidity and low mortality, leading to great economic impacts for the producing farms. Commercially available vaccines, although they help in the control of clinical signs and lesions in the respiratory tract, do not prevent infection and colonization of the epithelium of these animals. Therefore, the objective of the study will be to evaluate the efficacy of different vaccination protocols against Mycoplasma hyopneumoniae with the administration of a booster dose of the oral vaccine containing the nanostructured silica SBA-15 as an adjuvant in the finishing phase. To carry out this project, 40 piglets with 21 days of age will be acquired from a farm free of M. hyopneumoniae, which will be divided into four experimental groups, namely: G1 (negative control): piglets that will not receive any type of immunization; G2: piglets vaccinated at 25 days of age with a single-dose commercial vaccine against M. hyopneumoniae; G3: piglets vaccinated at 25 days of age (D0) with a single-dose commercial vaccine against M. hyopneumoniae, receiving a booster dose of the oral vaccine containing SBA-15 silica at 65 days (D40); G4: piglets vaccinated at 25 days of age (D0) with one dose of the oral vaccine containing SBA-15 silica against M. hyopneumoniae, receiving a booster dose of the same oral vaccine at 65 days (D40). Fifteen days after administration of the booster doses of the vaccines (D55), two animals from each group will be euthanized and the other eight will be challenged with 10^6 CCU/ml of M. hyopneumoniae via the endotracheal route; the remaining animals will be euthanized 45 days after the last immunizations (D85). Immediately before immunization (D0), the animals will be weighed and undergo a physical examination, as well as blood collection and nasal and laryngeal swabs. After the first collection, the animals will be weighed at D15, D40, D55, DD65, D75, and D85 to calculate daily weight gain. To evaluate cytokine expression (IFN-¿, IL-6, and IL-10), blood serum from samples collected at D0, D3, D40, D43, D55, and D58 will be used by ELISA. The detection of IgA and IgG will be performed using nasal swabs and blood serum samples from D0, D15, D40, D55, D65, D75, and D85. After the animals are challenged (D55), laryngeal swabs will be collected to assess the excretion of M. hyopneumoniae on D58, D65, D75, and D85. The evaluation of macroscopic lesions in the lungs and the collection of lung and spleen fragments will be performed during the necropsy of the animals. The collected spleen samples will be used to assess the expression of cytokines (IFN-¿, IL-6, IL-10, IL-17, and TNF-¿). The histopathology technique will be used to detect lung lesions resulting from infection by the pathogen after the animals are challenged. The data obtained will first be subjected to the Shapiro-Wilk test to test for normality. If the data present a normal distribution, they will be subjected to analysis of variance (ANOVA) with Tukey's test (p<0.05) for comparison between groups. And if normality has not been proven or the data are nonparametric, the Kruskal-Wallis test with Dunn's test (p<0.05) will be used. The Pearson or Spearman test will be used to assess correlations between the variables studied. (AU)