Oral Vaccination against Lawsonia intracellularis Changes the Intestinal Microbiome in Weaned Piglets

SIMPLE SUMMARY: Lawsoniaintracellularis is an obligately intracellular enteric bacterium that infects intestinal epithelial cells causing porcine proliferative enteropathy, which is responsible for economic losses in the swine industry worldwide. This study evaluated the effects of a commercial, oral attenuated L. intracellularis vaccination (Enterisol(®) Ileitis) on the intestinal microbial community of weaned piglets. Piglets were experimentally vaccinated with different doses of the L. intracellularis vaccine, and the gut microbial shifts were measured at weeks 0 and 6 post-vaccination. The data presented here demonstrated that oral vaccination against L. intracellularis shapes the gut microbiota in weaned piglets. Alpha diversity analysis revealed that vaccination led to significant changes in species evenness but no changes in species richness of the gut microbiota. Beta diversity analysis revealed that vaccination against L. intracellularis caused a shift in the microbial community structure. At the phylum level, Firmicutes and Bacteroidetes were the most abundant phyla in the intestinal microbiota of piglets regardless of treatment group and time points. At the genus level, there was a significant increase in Streptococcus and a significant decrease in Clostridium in the fecal microbiota of vaccinated pigs, regardless of the dose. Overall, this study sheds a new light on the potential role of the pig microbiota in modulating vaccine responses. ABSTRACT: Lawsoniaintracellularis, which causes porcine proliferative enteropathy (PPE), is a common swine intestinal pathogen that is prevalent in pig production sites worldwide. In this study, the alteration in the microbiome composition of weaned pigs was investigated in response to vaccination against L. intracellularis, using 16S rRNA gene sequencing. A total of 64 crossbred (Duroc × [Landrace × Yorkshire]) healthy weanling pigs weaned at 4 weeks of age were randomly assigned to four treatment groups (four pigs/pen; four pens/treatment), using a randomized complete block design for the 42-day trial. Pigs in the treatment groups were orally administered with three different doses (1 dose = 2 mL) of vaccine against L. intracellularis (Enterisol(®) Ileitis, Boehringer Ingelheim Vetmedica GmbH), namely the following: LAW1 (0.5 dose), LAW2 (1 dose), LAW3 (2 dose). A non-vaccinated group served as a negative control (CONT). Alpha diversity analysis revealed that vaccination led to significant changes in species evenness but not species richness of the gut microbiota. Beta diversity analysis revealed that vaccination against L. intracellularis caused a significant shift in the microbial community structure. At the genus level, there was a significant increase in Streptococcus and a significant decrease in Clostridium in the fecal microbiota of vaccinated pigs, regardless of dose.