Development of new inovation vaccine protocols against Mycoplasma hyopneumoniae and Circovirus (PCV-2) for the control of Porcine Respiratory Disease Complex

• Grant number: 24/21712-3
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2025
• End date: August 31, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Luís Guilherme de Oliveira
• Grantee: Luís Guilherme de Oliveira
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The Porcine Respiratory Disease Complex is one of the sanitary challenges in intensive pig farming, with a particular focus on infections caused by Mycoplasma (M.) hyopneumoniae and porcine circovirus type 2 (PCV-2). These co-infections cause significant production losses, and current vaccination protocols, while reducing clinical signs and lesions, do not completely prevent infection and pathogen dissemination. This project aims to evaluate the efficacy and immune response of different vaccination protocols, including commercial vaccines and a new oral vaccine, with booster doses during the finishing phase. For this study, 120 piglets aged 21 days will be selected from a farm certified as free of M. hyopneumoniae. These piglets will be divided into 8 groups, each subjected to different vaccination protocols as follows: G1: Piglets without vaccination; G2: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2; G3: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2, revaccinated with the same M. hyopneumoniae vaccine at 65 days; G4: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2, revaccinated at 65 days with a different M. hyopneumoniae vaccine; G5: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2, revaccinated with both vaccines at 65 days; G6: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2, revaccinated at 65 days against PCV-2; G7: Piglets vaccinated at 25 days against M. hyopneumoniae and PCV-2, revaccinated with an oral vaccine at 65 days; G8: Piglets vaccinated at 25 days with an oral M. hyopneumoniae vaccine and PCV-2, revaccinated with the oral vaccine at 65 days. Fifteen days after the administration of the second dose of vaccines, the animals will be challenged with M. hyopneumoniae by endotracheal route on D55. The animals will be euthanized 45 days after receiving the last dose of the vaccination protocol. Physical examinations, weighing, and biological sample collection will begin on the day of the first vaccination (D0), when blood samples and nasal and laryngeal swabs will be collected. Clinical evaluation will include cough monitoring and animal weighing to calculate daily weight gain on D15, D40, D55, D65, D75, and D85. Blood samples will be collected for the analysis of cytokines IFN-gamma, IL-6, and IL-10 by ELISA at different points, D0, D3, D40, D43, D55, and D58. These same cytokines will also be analyzed in the bronchoalveolar lavage fluid (BALF). Blood samples and nasal swabs will be collected to detect IgG and IgA, respectively, on D0, D15, D40, D55, D65, D75, and D85. The serum collected will be used to analyze PCV-2 viremia through qPCR. Acute phase proteins will be evaluated from serum collected 8, 24, and 72 hours after the second vaccination. After the challenge with M. hyopneumoniae, laryngeal swabs will be collected on D58, D65, D75, and D85 to assess pathogen shedding. Lung lesions will be monitored by computed tomography on D54 and D83. Nasal swabs and BALF samples will be analyzed for respiratory microbiota. The Pneumonia Index and collection of lung, lymph nodes, and BALF samples will occur during necropsy. Lung samples will be evaluated for cytokine expression (IFN-gamma, IL-6, IL-10, IL-17, and TNF-alpha). Lymph node fragments will be used to detect PCV-2. Lung fragments will be subjected to histopathological analysis and qPCR for both agents. These detailed analyses will allow a precise evaluation of the vaccines' efficacy and their influence on the animals' immune responses. Normality will be verified using Shapiro-Wilk and Bartlett tests. If assumptions are met, ANOVA and Tukey's test for multiple comparisons will be applied. If normality is not achieved, non-parametric tests (Kruskal-Wallis) will be used. Pearson or Spearman correlation will analyze potential correlations between quantitative variables based on the assumption of compliance (AU)