This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
This Science Page is from researchers Pau Obregon‑Gutierrez, Martí Cortey, Gerard E. Martin‑Valls, Hepzibar Clilverd, Florencia Correa‑Fiz, Virginia Aragón and Enric Mateu from Centre de Recerca en Sanitat Animal (CReSA) and the Universitat Autònoma de Barcelona, in Spain.
Key points:
- Piglets that survived early-life infection with a highly virulent PRRSV-1 strain displayed greater nasal microbiota diversity at three weeks of age compared to non-survivors.
- Non-survivors exhibited a dysbiotic community dominated by Escherichia, indicating that specific microbial profiles may contribute to resilience against PRRSV-1.
- These differences do not appear to be specific to PRRSV infection but were also associated with piglet survival in batches prior to the outbreak.
Introduction
The emergence of highly virulent strains of Porcine reproductive and respiratory syndrome virus (PRRSV) has become a major cause of mortality and economic losses worldwide. In previous studies it was shown that PRRSV can have a deep impact on the microbial communities of infected pigs. The present study explores how nasal microbiota influences or can be related to piglet survival during an outbreak caused by a highly virulent PRRSV-1 strain. By examining the differences in nasal microbiota between surviving and non-surviving piglets, the research aims to gain insight on the role of microbiota on the resilience to the infection.
Material and methods
The study was conducted on a 1400-sow farm where a highly virulent PRRSV-1 strain emerged in December 2021. Taking advantage of the fact that respiratory agents were periodically monitored in farrowing units and nurseries, a cohort of 31 three-week-old PRRSV-infected piglets from different litters was examined. Animals were divided into survivors (S) and non-survivors (D) at the end of the nursery period. PRRSV and IAV infections were confirmed using RT-qPCR, while DNA from nasal swabs underwent 16S rRNA sequencing. Bioinformatics analyses (using QIIME2) identified microbial diversity, richness, and taxonomy, with comparisons between groups using statistical tests and diversity metrics like Chao1 and Shannon indices. Differentially abundant taxa and inferred functional pathways were analyzed with Songbird, ANCOM, and PICRUSt2. Microbiome data integration and visualization were done in RStudio.
Results and discussion
The nasal microbiota composition differed significantly between S and D piglets. Survivors showed higher bacterial richness (Chao1 index, P = 0.001) but similar diversity (Shannon index, P = 0.66). Beta diversity analysis showed distinct clustering between S and D, with microbial differences partly influenced by the litter of origin. Interestingly, group D had higher abundances of Enterobacteriaceae and Escherichia.
Pre-outbreak samples showed similar clustering by survival outcomes, suggesting microbiota differences predated the PRRSV-1 outbreak and were related with an overall increased survivability. Sow microbiota also differed based on litter survival outcomes and between pre- and post-outbreak periods, linking microbiota composition across generations.
This article is available at: https://rdcu.be/d8qWW
