Marked reduction of SARS-CoV-2 infection and improved recovery following supplementation with a probiotic mix of four strains and two strains of Bifidobacterium breve in hamsters.

Only a few studies have shown that certain probiotics have beneficial effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this study, two strains of Bifidobacterium breve, CNCM I-5644 and CNCM I-5979, selected for their in vitro immunomodulatory properties demonstrated in a screening of 20 strains and a mixture of 4 probiotic strains selected based on its immunomodulatory and antiviral properties were evaluated in a hamster model of SARS-CoV-2 infection. Supplementation with these probiotics (7 days before plus 7 days after infection) reduced SARS-CoV-2 infection with a significantly reduced viral load in the upper respiratory tract and lungs and improved weight recovery. Probiotics also counteracted the increase in inflammatory markers and intestinal permeability. The impact of these probiotics was independent of microbiota composition and short-chain fatty acid production. Overall, these data suggest that the probiotics tested, in particular the mix containing Bifidobacterium longum LA101, Lactobacillus helveticus LA102, Lactococcus lactis LA103, and Streptococcus thermophilus LA104, can facilitate recovery from SARS-CoV-2 infection (as shown by weight regain in infected hamsters) by reducing viral load and inflammation.

Importance: Our study investigated the potential benefits of specific probiotics in fighting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19). We tested two strains of Bifidobacterium breve selected based on their immune-boosting properties, along with a commercial mix of four probiotic strains chosen for its antiviral and immune-modulating effects. These probiotics were administered to hamsters over a week before and a week after infection. Supplementation with these probiotics significantly reduced the viral load in the upper respiratory tract and lungs, promoting recovery as demonstrated by the weight regain observed. In addition to reducing viral presence, the probiotics also helped lower inflammation and improved gut health by counteracting increased intestinal permeability. Our findings suggest that probiotics, particularly the mix of four strains, could support recovery from SARS-CoV-2 infection by reducing inflammation, viral load, and enhancing overall health.