The immune response of pregnant sow after vaccination with crude fimbriae (F4) extracts vaccine and immunoprotection of nursery pig against pathogenic E. coli (F4+ETEC)

• Published in: Acta tropica 2024-06, Vol.254, p.107173-107173, Article 107173
• Main Authors: Nguyet, Luong Thi Yen, Ounjai, Puey, Ngamwongsatit, Natharin, Kaeoket, Kampon
• Format: Article
• Language: English
• Subjects: Diarrhea; E. coli; F4 fimbriae; pig; vaccine
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2024.107173

•We prepared Frimbria F4 protein as use as antigen to stimulate immune response in the sow serum and follows the level in the sow colostrum and serum of piglets for the first time.•We also used the same antigen to stimulate the immune response in weaned pig and challenging them, the pathogen was cleared from the GI tract faster in vaccinated group. Neonatal and post-weaning diarrhea is a concern disease caused by enterotoxigenic Escherichia coli fimbriae F4 (F4+ETEC) in pig farms. Diarrhea outbreaks are often severe and costly due to the high prevalence and spread of the disease within the same herd. Vaccine is one of strategic solution in protecting pig against F4+ETEC infection in particular pig farm. In present study, we conducted two trials of vaccination with crude F4 fimbriae extract vaccine in pregnant sow and nursery pigs. In experiment 1 (20 sows; non-vaccinated control, n=10), we vaccinated pregnant sows (n=10) twice at 4 wk and 2 wk before farrowing and evaluated impact of vaccination on maternal immunity. The sow serum and colostrum were collected before vaccination, 2 and 4 weeks after vaccination, 6 hours after farrowing, respectively, and the piglet's serum from both groups (2 piglet/sow, 10 piglets from each group) were also collected on 3 days old to measure F4 specific IgG, F4 specific IgA using in house ELISA kit. In experiment 2, to optimize doses and dosage of candidate vaccine in piglets, 18 piglets (3 piglets/group) were allocated into five immunized groups and one control group (unimmunized group), we immunized piglets twice at 4 and 6 weeks old with difference doses (i.e., 0, 50, 100, 150, 200 µg), and for a dose 150 µg, we immunized with two dosages at 1 ml and 2 ml. Piglets were challenged with a 3 ml dose of 3 × 109 CFU/ml bacterial culture of enterotoxigenic Escherichia coli (F4+ETEC) in order to evaluate the efficacy of vaccine. After challenging, the clinical sign of the piglets was daily observed and the rectal swab was performed every day for investigation of the fecal shedding of Escherichia coli (F4+ETEC) by using PCR technique. Serum were collected before, 2 and 4 weeks after vaccination and 1 week after challenge to measure F4 specific IgG, F4 specific IgA using in house ELISA kit and cytokines levels (i.e., IL-1 beta, IL-6, IL-8 and TNF alpha) before and 1 week after challenge using commercial ELISA kit. The levels of antibody results showed that in experiment 1, the anti-F4 antibody levels both F4 specific IgG and F4