Antiviral effects of a probiotic Enterococcus faecium strain against transmissible gastroenteritis coronavirus

The general composition of the faecal virome of pigs depends on age, but not on feeding with a probiotic bacterium

BACKGROUND

The pig faecal virome, which comprises the community of viruses present in pig faeces, is complex and consists of pig viruses, bacteriophages, transiently passaged plant viruses and other minor virus species. Only little is known about factors influencing its general composition. Here, the effect of the probiotic bacterium Enterococcus faecium (E. faecium) NCIMB 10415 on the pig faecal virome composition was analysed in a pig feeding trial with sows and their piglets, which received either the probiotic bacterium or not.

RESULTS

From 8 pooled faecal samples derived from the feeding trial, DNA and RNA virus particles were prepared and subjected to process-controlled Next Generation Sequencing resulting in 390,650 sequence reads. In average, 14% of the reads showed significant sequence identities to known viruses. The percentage of detected mammalian virus sequences was highest (55-77%) in the samples of the youngest piglets and lowest (8-10%) in the samples of the sows. In contrast, the percentage of bacteriophage sequences increased from 22-44% in the youngest piglets to approximately 90% in the sows. The dominating mammalian viruses differed remarkably among 12 day-old piglets (kobuvirus), 54 day-old piglets (boca-, dependo- and pig stool-associated small circular DNA virus [PigSCV]) and the sows (PigSCV, circovirus and "circovirus-like" viruses CB-A and RW-A). In addition, the Shannon index, which reflects the diversity of sequences present in a sample, was generally higher for the sows as compared to the piglets. No consistent differences in the virome composition could be identified between the viromes of the probiotic bacterium-treated group and the control group.

CONCLUSION

The analysis indicates that the pig faecal virome shows a high variability and that its general composition is mainly dependent on the age of the pigs. Changes caused by feeding with the probiotic bacterium E. faecium could not be demonstrated using the applied metagenomics method.

Cross-talk Between Host, Microbiome and Probiotics: A Systems Biology Approach for Analyzing the Effects of Probiotic Enterococcus faecium NCIMB 10415 in Piglets

A comprehensive data-set from a multidisciplinary feeding experiment with the probiotic Enterococcus faecium was analyzed to elucidate effects of the probiotic on growing piglets. Sixty-two piglets were randomly assigned to a control (no probiotic treatment) and a treatment group (E. faecium supplementation). Piglets were weaned at 26 d. Age-matched piglets were sacrificed for the collection of tissue samples at 12, 26, 34 and 54 d. In addition to zootechnical data, the composition and activity of intestinal microbiota, immune cell types, and intestinal responses were determined. Our systems analysis revealed clear effects on several measured variables in 26 and 34 days old animals, while response patterns varied between piglets from different age groups. Correlation analyses identified reduced associations between intestinal microbial communities and immune system reactions in the probiotic group. In conclusion, the developed model is useful for comparative analyses to unravel systems effects of dietary components and their time resolution. The model identified that effects of E. faecium supplementation most prominently affected the interplay between intestinal microbiota and the intestinal immune system. These effects, as well as effects in other subsystems, clustered around weaning, which is the age where piglets are most prone to diarrhea.

Dietary Enterococcus faecium NCIMB 10415 and zinc oxide stimulate immune reactions to trivalent influenza vaccination in pigs but do not affect virological response upon challenge infection

Swine influenza viruses (SIV) regularly cause significant disease in pigs worldwide. Since there is no causative treatment of SIV, we tested if probiotic Enterococcus (E.) faecium NCIMB 10415 or zinc (Zn) oxide as feed supplements provide beneficial effects upon SIV infection in piglets. Seventy-two weaned piglets were fed three different diets containing either E. faecium or different levels of Zn (2500 ppm, Zn^high; 50 ppm, Zn^low). Half of the piglets were vaccinated intramuscularly (VAC) twice with an inactivated trivalent SIV vaccine, while all piglets were then infected intranasally with H3N2 SIV. Significantly higher weekly weight gains were observed in the E. faecium group before virus infection, and piglets in Zn^high and E. faecium groups gained weight after infection while those in the control group (Zn^low) lost weight. Using ELISA, we found significantly higher H3N2-specific antibody levels in the E. faecium+VAC group 2 days before and at the day of challenge infection as well as at 4 and 6 days after challenge infection. Higher hemagglutination inhibition (HI) titers were also observed in the Zn^high+VAC and E. faecium+VAC groups at 0, 1 and 4 days after infection. However, there were no significant differences in virus shedding and lung lesions between the dietary groups. Using flow cytometry analysis significantly higher activated T helper cells and cytotoxic T lymphocyte percentages in the PBMCs were detected in the Zn^high and E. faecium groups at single time points after infection compared to the Zn^low control group, but no prolonged effect was found. In the BAL cells no influence of dietary supplementation on immune cell percentages could be detected. Our results suggest that feeding high doses of zinc oxide and particularly E. faecium could beneficially influence humoral immune responses after vaccination and recovery from SIV infection, but not affect virus shedding and lung pathology.

Functional characteristics of porcine peripheral T cells stimulated with IL-2 or IL-2 and PMA

In human or mouse, mature T cells express either CD4 or CD8, resulting in different functions in the periphery. Interestingly, porcine CD4 and CD8 double positive (DP) T cells are present in the blood, and their proportions change from youth to adulthood. However, the features of these cells in swine are poorly understood. We investigated the fate of porcine peripheral T cells based on their functional characteristics, including proliferation and the expression of CD4 and CD8 co-receptors. The results showed that all the populations changed their CD8 expression in a time-dependent manner and porcine T cells had different proliferative pattern from human T cells. The results further revealed that Th2 cytokines were increased later in porcine T cells compared to human T cells upon stimulation with IL-2+PMA. Collectively, we found that the fate of porcine peripheral T cells is different from that of human T cells, and the changes occur in a time- and stimulation-dependent manner.