This study aimed to investigate the effects of dietary live yeast (LY) supplementation on growth, intestinal permeability and immunological parameters of piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Piglets weaned at 21 d were allocated into three treatments with six pens and six piglets per pen, receiving the control diet (CON), diets supplemented with antibiotics plus zinc oxide (ANT-ZnO) and LY (Saccharomyces cerevisiae strain CNCM I-4407), respectively, for a period of 2 weeks. On day 8, thirty-six piglets were selected as control without ETEC (CON), CON-ETEC, ANT-ZnO-ETEC and LY-ETEC groups challenged with ETEC until day 10 for sample collections. Piglets fed ANT-ZnO diet had the highest average daily gain and average daily feed intake (P<0·05) during the 1st week, but ADG of piglets fed the ANT-ZnO diet was similar as piglets fed LY diet during the second week. Piglets with LY-ETEC or ANT-ZnO-ETEC had markedly lower diarrhoea score (P<0·05) than piglets with CON-ETEC during the 24 h after ETEC challenge. Relative to piglets with CON, the counts of E. coli, urinary ratio of lactulose to mannitol, plasma IL-6 concentration, mRNA abundances of innate immunity-related genes in ileum and mesenteric lymph node tissues were increased (P<0·05), whereas the villous height of jejunum and relative protein expression of ileum claudin-1 were decreased (P<0·05) in piglets with CON-ETEC; however, these parameters did not markedly change in piglets with LY-ETEC or ANT-ZnO-ETEC. In summary, dietary LY supplementation could alleviate the severity of diarrhoea in piglets with ETEC, which may be associated with the improved permeability, innate immunity and bacterial profile.

One mechanism through which S . cerevisiae may improve the performance of pigs is by altering the composition of the gut microbiota, a response that may be enhanced by early postnatal supplementation of probiotics. To test this hypothesis, newborn piglets (16 piglets/group) were treated with either S . cerevisiae yeast (5 x 10 9 cfu/pig: Low) or (2.5 x 10 10 cfu/piglet: High) or equivalent volume of sterile water (Control) by oral gavage every other day starting from day 1 of age until weaning (28±1 days of age). Piglet body weight was recorded on days 1, 3, 7, 10, 17, 24 and 28 and average daily gain (ADG) calculated for the total period. At weaning, piglets were euthanized to collect cecum content for microbial profiling by sequencing of the 16S rRNA gene. ADG was higher in both Low and High yeast groups than in Control group ( P <0.05). Alpha diversity analyses indicated a more diverse microbiota in the Control group compared with Low yeast group; the High yeast being intermediate ( P < 0.01). Similarly, Beta diversity analyses indicated differences among treatments ( P = 0.03), mainly between Low yeast and Control groups ( P = 0.02). The sparse Partial Least Squares Discriminant Analysis (sPLS-DA) indicated that Control group was discriminated by a higher abundance of Veillonella , Dorea , Oscillospira and Clostridium ; Low yeast treated pigs by higher Blautia , Collinsella and Eubacterium ; and High yeast treated pigs by higher Eubacterium , Anaerostipes , Parabacteroides , Mogibacterium and Phascolarctobacterium . Partial Least Squares (PLS) analysis showed that piglet ADG was positively correlated with genus Prevotella in High yeast group. Yeast supplementation significantly affected microbial diversity in cecal contents of suckling piglets associated with an improvement of short chain fatty acid producing bacteria in a dose-dependent manner. In conclusion, yeast treatment improved piglet performance and shaped the piglet cecum microbiota composition in a dose dependent way.

As an alternative to antibiotic growth promoters, live yeast supplementation has proven useful in reducing weaning stress and improving performance parameters of piglets. Here, we compared the performance and hindgut microbiota of weanling piglets subjected to different pre- and post-weaning yeast supplementation regimens using a live strain of Saccharomyces cerevisiae (Actisaf Sc 47). Average feed intake and average daily weight gain of piglets within Yeast-Control and Yeast-Yeast groups were higher than those in the Control-Control group. Yeast supplementation resulted in development of microbial communities that were phylogenetically more homogenous and less dispersed compared to the microbiota of control piglets. Key bacterial taxa overrepresented in the microbiota of yeast supplemented piglets included phylum Actinobacteria, specifically family Coriobacteriaceae, as well as Firmicutes families Ruminococcaceae, Clostridiaceae, Peptostreptococcaceae, and Peptococcaceae. Correlation network analysis revealed that yeast supplementation was associated with enrichment of positive correlations among proportions of different bacterial genera within the hindgut ecosystem. In particular, within the cecal microbiota of supplemented piglets, higher numbers of positive correlations were observed among potentially beneficial genera of the phyla Actinobacteria and Firmicutes, suggesting a mechanism by which yeast supplementation may contribute to regulation of intestinal homeostasis and improved performance of piglets.

We investigated the efficacy of a novel microparticle (MP) based vaccine formulation consisting of pertussis toxoid (PTd), polyphosphazene (PCEP), CpG ODN 10101 and synthetic cationic innate defense regulator peptide 1002 (IDR) against Bordetella pertussis in mice. We studied whether encapsulation of these IDR-CpG ODN complexes into polyphosphazene-based microparticles further enhanced their immunomodulatory activity compared to soluble formulations containing PCEP (SOL), or without PCEP (AQ). In vitro stimulation of murine macrophages showed MP induced significantly higher levels of pro-inflammatory cytokines. When assessed in a B. pertussis infection challenge model, a single immunization with MP formulation led to significantly lower bacterial loads compared to other formulations and non-vaccinated animals. ELISPOT of splenocytes showed that MP group mice had significantly higher number of antigen-specific IL-17 secreting cells. The cytokine profile in lung homogenates of MP group mice after challenge showed significantly higher amounts of MCP-1, TNF-α, IFN-γ, IL-12 and IL-17 and significantly lowered IL-10 levels suggesting a strong Th1 shift. Protection was observed against challenge infection with B. pertussis. On the other hand protective immune responses elicited in Quadracel(®) immunized mice were Th2 skewed. Hence, we conclude that formulation of PTd, PCEP, CpG ODN and IDR into MP generates a protective immune response in mice against pertussis emphasizing the potential of MP as a delivery vehicle for the potential development of single-shot vaccines.

Neonatal bacille Calmette-Guerin (BCG) vaccination is widely employed to protect against tuberculosis. Predominant Th1 but not mixed Th1/Th2 responses are thought to be protective. If so, effective vaccination must cause Th1 imprints. The immune system of infants differs from that of adults and such differences could critically affect neonatal vaccination. We demonstrate that BCG infection of infant and adult mice produces similar responses. Infection with low and high numbers of BCG, respectively, leads to sustained Th1 and mixed Th1/Th2 responses. Low-dose but not high-dose infection also results in Th1 imprints, guaranteeing a Th1 response upon high-dose challenge, and resulting in optimal bacterial clearance. Our observations on low-dose Th1 imprinting are intriguing in the context of the well-known madras trial. In this trial, the highest dose of BCG, which had insignificant side effects, was administered to over 250,000 human subjects. This high-dose vaccination resulted in insignificant protection against tuberculosis.