Research paper Effect of b-glucans on an ETEC infection in piglets E. Stuyven a, *, E. Cox a , S. Vancaeneghem a , S. Arnouts a , P. Deprez c , B.M. Goddeeris a,b a Laboratory of Immunology, Faculty of Veterinary Medicine, UGent, Salisburylaan 133, B-9820 Merelbeke, Belgium b Faculty of Bioscience Engineering, Department of Biosystems, K.U.Leuven, Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium c Department of Internal Medicine and Clinical Biology of Large Animals, Faculty of Veterinary Medicine, University Ghent, Merelbeke, Belgium 1. Introduction Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrhoea in neonatal, suckling and newly weaned piglets. During the neonatal and suckling period, the piglets can be passively protected by antibodies preset in milk (Rutters and Jones, 1973; Deprez et al., 1986; Osek et al., 1995). This protection disappears at weaning, making weaned piglets susceptible again to an ETEC infection (Hampson, 1994). Weaned piglets need an active immunity to be protected against ETEC. We have shown that an oral immunisation of weaned piglets with purified F4 fimbriae results in an immune response (Van den Broeck et al., 1999a,b) that completely protects piglets against a challenge infection that occurs 24 days later (Verdonck et al., 2004). This response, however, comes too late to protect piglets against ETEC-induced weaning diarrhoea, since ETEC infections most often occur the first week after weaning. Attempts to immunize piglets during the suckling period did not result in a complete protection (Snoeck et al., 2003). Therefore a vaccine inducing protective immunity at weaning that can be given during the suckling period is not available yet. The prophylactic use of antibiotics could also protect piglets, but is prohibited in Europe since January 2006. Therefore, alternatives are searched for in order to prevent infection on problem farms. b-Glucans, polymers of D-glucose extracted from the cell wall of bacteria, fungi or yeast, are known as immunostimulators. b-Glucans have the capacity to activate the innate immune system, thereby enhancing the defence barriers and thus providing protection against Veterinary Immunology and Immunopathology 128 (2009) 60–66 ARTICLE INFO Keywords: b-Glucans Immunostimulation In vivo Pigs ABSTRACT The effect of orally administered b-glucans in protecting pigs against an ETEC infection after weaning was analysed in this study. Three b-glucans that differed in origin (Saccharomyces cerevisiae (MCG (Macrogard) and G2) or Sclerotium rolfsii (G3)) and/or extraction procedure were tested. Pigs fed for 2 weeks after weaning with these glucans were less susceptible to an F4 + ETEC infection in comparison with the control group. This was evidenced by a reduction in the faecal excretion of F4 + Escherichia coli as well as a reduced F4-specific serum antibody response. This decrease in faecal excretion was statistically significant for pigs fed with the MCG glucan in a first experiment and with the G3 glucan in a second experiment; diarrhoea was milder in the glucan-supplemented groups and was significantly reduced in the MCG-supplemented group. Furthermore, a lower amount of F4-specific IgM antibody-secreting cells (ASC) was found in the lymphoid tissues of pigs fed with G2 or G3 glucans in comparison with the control pig, as well as lower F4-specific IgA ASC in G3-fed pigs in comparison with the control pig. This study showed that b-glucans can protect against an ETEC infection. Both MCG from S. cerevisiae and G3 from S. rolfsii, resulted in significant effects. To our knowledge, this is the first in vivo study, in which the use of b-glucans as feed ingredient for just-weaned piglets was tested for their protective effects against ETEC infection. ß 2008 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +32 92647384; fax: +32 92647496. E-mail address: Edith.Stuyven@UGent.be (E. Stuyven). Contents lists available at ScienceDirect Veterinary Immunology and Immunopathology journal homepage: www.elsevier.com/locate/vetimm 0165-2427/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2008.10.311