Influence of pig gut microbiota on Mycoplasma hyopneumoniae susceptibility

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In this open-access article from the MycoLab, Dr. Maria Pieters’ team explores the influence of pigs’ gut microbiome in modulating their susceptibility to Mycoplasma hyopneumoniae.

In a commercial sow farm, thirty-two piglets from six litters, naive against PRRS and M. hyopneumoniae were randomly selected. Fecal swabs were collected to evaluate the piglets’ gut microbiome at 3, 8, and 12 weeks of age. Except for two control pigs, all animals were inoculated intra-tracheally with M. hyopneumoniae at 8 weeks of age. At 12 weeks, lungs were collected and evaluated for total lesion score suggestive of enzootic pneumoniae. The gut microbiome was evaluated by amplifying and sequencing the 16s RNA gene. The sequences were then mapped to a taxonomy file.

figure1
Lung lesion scores (LS) were plotted against piglet ID.

Lung lesion scores showed that even though the highest (20%) and lowest (2.5%) scores were obtained by piglets from different litters, there was a clustering of lung lesions based on the litter of origin.

When analyzing the gut microbiomes, 99% was made of firmicutes, bacteroidetes, proteobacteria, fusobacteria and spirochetes.

However, the variety of species observed changed between piglets. Pigs with lower lung lesion scores showed an inreased number of bacterial species in their gut microbiome compared to pigs with higher lung lesion scores. Additionally, the diversity of species observed was the highest when the piglets were the youngest. Microbial diversity were less present in pigs at 8 and 12 weeks of age compared to pigs at 3 weeks of age. The presence of bacteria from the Ruminococcaceae family was the most discriminative of litters with low lung lesions.

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Correlation between fecal microorganisms and lung lesion scores

The entire article is available on the Veterinary Research journal website.

Abstract

This study investigated the influence of gut microbiome composition in modulating susceptibility to Mycoplasma hyopneumoniae in pigs. Thirty-two conventional M. hyopneumoniae free piglets were randomly selected from six different litters at 3 weeks of age and were experimentally inoculated with M. hyopneumoniae at 8 weeks of age. Lung lesion scores (LS) were recorded 4 weeks post-inoculation (12 weeks of age) from piglet lungs at necropsy. Fecal bacterial community composition of piglets at 3, 8 and 12 weeks of age were targeted by amplifying the V3–V4 region of the 16S rRNA gene. The LS ranged from 0.3 to 43% with an evident clustering of the scores observed in piglets within litters. There were significant differences in species richness and alpha diversity in fecal microbiomes among piglets within litters at different time points (p < 0.05). The dissimilarity matrices indicated that at 3 weeks of age, the fecal microbiota of piglets was more dissimilar compared to those from 8 to 12 weeks of age. Specific groups of bacteria in the gut that might predict the decreased severity of M. hyopneumoniae associated lesions were identified. The microbial shift at 3 weeks of age was observed to be driven by the increase in abundance of the indicator family, Ruminococcaceae in piglets with low LS (p < 0.05). The taxa, Ruminococcus_2 having the highest richness scores, correlated significantly between litters showing stronger associations with the lowest LS (r = −0.49, p = 0.005). These findings suggest that early life gut microbiota can be a potential determinant for M. hyopneumoniae susceptibility in pigs.

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