Sow vaccination against virulent Glaesserella parasuis shapes the nasal microbiota of their offspring

Abstract

Glaesserella parasuis is the etiological agent of Glässer's disease, a common pathology in the pork industry with higher prevalence in the postweaning period. Vaccination is one of the strategies to control this disease. Here, we investigated the effect that sow vaccination against virulent strains of G. parasuis had in the nasal microbiota of their offspring. Nasal swabs from fifteen days-old piglets from vaccinated (vs-P, n = 11) and unvaccinated sows (cs-P, n = 11) were obtained and DNA was extracted for 16S amplicon sequencing. Microbiota composition was different, with lower diversity in vs-P, and a strong clustering of the groups in beta diversity analysis. Among the 1509 sequences associated to either study group, all the sequences classified as G. parasuis (10 ASVs) had lower relative abundance in the vs-P group. A list of 32 inferred metabolic pathways were statistically different between groups. A distinctive structure of the two microbial networks was detected, with modules in the cs-P not conserved in the vs-P network. In conclusion, vaccination of the sows had a large effect in the microbiota composition of their offspring that went beyond the effect on the targeted pathogen. The mechanisms underneath these changes may include alteration of the microbiota network due to the elimination of the targeted pathogen and/or immunological changes.

Figure 1

Alpha diversity measured as Simpson index and calculated as 1-D (A) and Simpson evenness index (B). Samples from nasal microbiota of 15-day-old piglets born to control unvaccinated sows (cs-P, orange boxes) and to vaccinated sows (vs-P, green boxes) with a vaccine against virulent G. parasuis were analyzed. These two indexes resulted statistically significant (P < 0.05).

Figure 2

PCoA plots representing the beta diversity of the nasal microbiota of piglets from vaccinated (green) and control unvaccinated sows (orange). Bray Curtis distance matrix is represented in the left (A) and weighted Unifrac index on the right (B). Each sample is colored based on the biological sow, and the size of the symbol is proportional to the Simpson index (alpha diversity).

Figure 3

Heatmap representing the top 30 most relative abundant ASVs globally. The relative abundance (log10) of each ASV in the nasal microbiota of piglets from control sows (cs-P) and vaccinated sows (vs-P) is shown. The biological mothers are indicated in the bottom as A, B, C and D.

Figure 4

Differential abundant features between nasal microbiota composition of piglets from control (cs-P, orange bars) or vaccinated sows (vs-P, green bars). The association of the 30 features with the highest differential ranked coefficient estimated with q2-songbird is depicted (log fold-change).

Figure 5

Subnetwork representing the module 6 of the co-occurrence network from the nasal microbiota of piglets from control sows (cs-P). Each node corresponds to ASVs and edges in the network represent the positive correlations between the different nodes. The nodes are colored based on the location of these ASVs in the network of the nasal microbiota composition of piglets from vaccinated sows (vs-P) modules. ASVs, in this module 6 from the cs-P network, that are present as the top ten most-connected nodes in the vs-P network, are represented in different colors regarding the modules they belong in the vs-P network: red, nodes in vs-P module 1; green, nodes in vs-P module 12; purple, nodes in vs-P module 2; black, node in vs-P module 32, and pink, for node in module 4. Yellow color highlights the most connected nodes in this module 6 from the cs-P network (6 nodes). The white node corresponds to an ASV classified as Erysipelotrichaceae, which is located in the same module as a G. parasuis ASV in the vs-P network. Diamond shaped nodes correspond to the four nodes that were absent in the vs-P network. Size of the nodes are proportional to their relative abundance, ranging from 0.0039% (Neisseria, one of the diamond shaped nodes) and 5.07% (SMB53, largest red-colored node).

Figure 6

PCA of the functional pathway composition of each sample. Samples from piglets from vaccinated sows (vs-P group) are represented as green squares and samples from piglets from control sows (cs-P group) are represented as oranges circles.

Figure 7

Predicted KEGG functional pathways using PICRUSt analysis. Most statistically significant differential pathways between the nasal microbiota of piglets from vaccinated (vs-P) and control sows (cs-P) are shown (Kruskal–Wallis post-hoc test with Bonferroni correction). Pathways more relatively abundant in the cs-P samples are shown on the left, and those more relatively abundant in the vs-P samples are shown on the right.