Use of Nanostructured Silica SBA-15 as an Oral Vaccine Adjuvant to Control Mycoplasma hyopneumoniae in Swine Production.

Mycoplasma hyopneumoniae is a difficult-to-control bacterium since commercial vaccines do not prevent colonization and excretion. The present study aimed to evaluate the performance of an orally administered vaccine composed of antigens extracted from Mycoplasma hyopneumoniae and incorporated into mesoporous silica (SBA-15), which has an adjuvant-carrier function, aiming to potentiate the action of the commercial intramuscular vaccine. A total of 60 piglets were divided into four groups (n = 15) submitted to different vaccination protocols as follows, Group 1: oral SBA15 + commercial vaccine at 24 days after weaning, G2: oral vaccine on the third day of life + vaccine commercial vaccine at 24 days, G3: commercial vaccine at 24 days, and G4: commercial vaccine + oral vaccine at 24 days. On the first day, the piglets were weighed and, from the third day onwards, submitted to blood collections for the detection and quantification of anti-Mycoplasma hyopneumoniae IgG. Nasal swabs were collected to monitor IgA by ELISA, and oropharyngeal swabs were used to assess the bacterial load by qPCR. Biological samples were collected periodically from the third day of life until the 73rd day. At 41 days of life, 15 individuals of the same age, experimentally challenged with an inoculum containing M. hyopneumoniae, were co-housed with the animals from groups (1 to 4) in a single pen to increase the infection pressure during the nursery period. At 73 days, all piglets were euthanized, and lungs were evaluated by collecting samples for estimation of bacterial load by qPCR. Quantitative data obtained from physical parameters and laboratory investigation were analyzed by performing parametric or non-parametric statistical tests. Results indicate that animals from G2 showed smaller affected lung areas compared to G3. Animals from G2 and G4 had a low prevalence of animals shedding M. hyopneumoniae at 61 days of age. Additionally, no correlation was observed between lung lesions and M. hyopneumoniae load in lung and BALF samples in animals that received the oral vaccine, while a strong correlation was observed in other groups. In the present study, evidence points to the effectiveness of the oral vaccine developed for controlling M. hyopneumoniae in pig production under field conditions.

Efficacy evaluation of a novel oral silica-based vaccine in inducing mucosal immunity against Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae, the main etiological agent of Porcine Enzootic Pneumonia, is widely spread in swine production worldwide. Its prevention is of great interest for the productive system, since its colonization in the lung tissue leads to intense production losses. This study aimed to compare the M. hyopneumoniae shedding and acute-phase response in 30 pigs submitted to different vaccination protocols: an experimental oral vaccine using a nanostructured mesoporous silica (SBA-15) as adjuvant (n = 10); an intramuscular commercially available vaccine at 24 days of age (n = 10); and a control group (n = 10) following experimental challenge with M. hyopneumoniae. Laryngeal and nasal swabs were collected weekly and oral fluids were collected at 7, 10, 14, 17, 23, 28, 35, 42, and 49 days post-infection to monitor pathogen excretion by qPCR. Nasal swabs were also used to detect anti-M. hyopneumoniae IgA by ELISA. Blood samples were collected for monitoring acute phase proteins. The antibody response was observed in both immunized groups seven days after vaccination, while the control group became positive for this immunoglobulin at 4 weeks after challenge. Lung lesion score was similar in the immunized groups, and lower than that observed in the control. SBA-15-adjuvanted oral vaccine provided immunological response, decreased shedding of M. hyopneumoniae and led to mucosal protection confirmed by the reduced pulmonary lesions. This study provides useful data for future development of vaccines against M. hyopneumoniae.

Oral vaccination of piglets against Mycoplasma hyopneumoniae using silica SBA-15 as an adjuvant effectively reduced consolidation lung lesions at slaughter.

Mycoplasma (M.) hyopneumoniae is the main pathogen of porcine enzootic pneumonia (PEP). Its controlling is challenging, and requires alternative strategies. This study aimed to develop an oral vaccine against M. hyopneumoniae using a nanostructured mesoporous silica (SBA-15) as an adjuvant, and compare its effect with an intramuscular (IM) commercial vaccine (CV). Fifty 24 day-old M. hyopneumoniae-free piglets composed five equal groups for different immunization protocols, consisting of a CV and/or oral immunization (OI). Control piglets did not receive any form of immunization. All piglets were challenged with M. hyopneumoniae strain 232 on D49 by tracheal route. IgA antibody response in the respiratory tract, bacterial shedding and serum IgG were evaluated. The piglets were euthanized on 28 (D77) and 56 (D105) days post-infection. Lung lesions were macroscopically evaluated; lung fragments and bronchoalveolar fluid (BALF) were collected for estimation of bacterial loads by qPCR and/or histopathology examination. All immunization protocols induced reduction on Mycoplasma-like macroscopic lung lesions. IgA Ab responses anti-M. hyopneumoniae, the expression of IL-4 cytokine and a lower expression of IL-8 were induced by CV and OI vaccines, while IgG was induced only by CV. Oral immunization using silica as a carrier-adjuvant can be viable in controlling M. hyopneumoniae infection.