Inhibitory Influence of Enterococcus faecium on the Propagation of Swine Influenza A Virus In Vitro

Abstract

The control of infectious diseases such as swine influenza viruses (SwIV) plays an important role in food production both from the animal health and from the public health point of view. Probiotic microorganisms and other health improving food supplements have been given increasing attention in recent years, but, no information on the effects of probiotics on swine influenza virus is available. Here we address this question by assessing the inhibitory potential of the probiotic Enterococcus faecium NCIMB 10415 (E. faecium) on the replication of two porcine strains of influenza virus (H1N1 and H3N2 strain) in a continuous porcine macrophage cell line (3D4/21) and in MDBK cells. Cell cultures were treated with E. faecium at the non-toxic concentration of 1×106 CFU/ml in growth medium for 60 to 90 min before, during and after SwIV infection. After further incubation of cultures in probiotic-free growth medium, cell viability and virus propagation were determined at 48 h or 96 h post infection. The results obtained reveal an almost complete recovery of viability of SwIV infected cells and an inhibition of virus multiplication by up to four log units in the E. faecium treated cells. In both 3D4/21- and MDBK-cells a 60 min treatment with E. faecium stimulated nitric oxide (NO) release which is in line with published evidence for an antiviral function of NO. Furthermore, E. faecium caused a modified cellular expression of selected mediators of defence in 3D4-cells: while the expression of TNF-α, TLR-3 and IL-6 were decreased in the SwIV-infected and probiotic treated cells, IL-10 was found to be increased. Since we obtained experimental evidence for the direct adsorptive trapping of SwIV through E. faecium, this probiotic microorganism inhibits influenza viruses by at least two mechanisms, direct physical interaction and strengthening of innate defence at the cellular level.

Prebiotic and Probiotic Approaches to Improving Food Safety on the Farm and Their Implications on Human Health

“…E. faecium was shown to increase cell survivability (40-80%) and reduce viral titers (up to 4 log) of both SwIV strains in two media [59]. In this publication, it was hypothesized and demonstrated that E. faecium operates through the adsorption of viral particles as well as the stimulation of nitric oxide production, which in itself has antiviral properties.…”

“…Enterococcus faecium NCIMB 10415 is a recognized probiotic approved by the European Union and has been evaluated for its efficacy in reducing swine influenza virus (SwIV), specifically H1N1 and H3N2 [59]. E. faecium was shown to increase cell survivability (40-80%) and reduce viral titers (up to 4 log) of both SwIV strains in two media [59].…”

Enterococcus faecium; a Suitable Probiotic Candidate for Modulation of Immune Responses Against Pathogens

“…21 The probiotic form of E. faecium (NCIMB 10415) also increased the production of NO by the phagocyte cells of pigs. 22 Based on the results, it appears that E. faecium modulates the innate immunity to fight against pathogens.…”

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

“…Function of jejunum epithelium 17 T 10 Jejunum gene expression 7 T 11 Jejunum morphology 3 T 12 Intestinal microbial metabolites in stomach digesta…”

“…In vitro experiments with porcine cell cultures have indicated a protective potential against virus infections. [11,12] Moreover, a previous feeding trial identified alterations of intestinal bacterial communities and immune parameters as a reaction to the supplementation of E. faecium NCIMB 10415 to growing piglets. [13] Results from another feeding trial with E. faecium NCIMB 10415 revealed a broad spectrum of effects: increased absorptive and secretory transport capacities, [14] improved intestinal barrier function of jejunum epithelia, [14] a reduced feed conversion ratio, [15] activation of cytotoxic T-cells, [16] but a lack of protection against Salmonella infection, [17] an altered occurrence of pathogenic genes in intestinal Escherichia coli (E. coli) populations [18] and altered expressions of cytokines.…”