Anti-herpes virus activity of lactobacillus’ postbiotics

BACKGROUND: Recently various lactic acid bacteria (LAB) and their post-metabolites have shown many positive effects on human and animal welfare. They appear to be beneficial in different disorders and pathological conditions, including in a broad-spectrum of infectious diseases. AIM: To estimate in vitro the anti-herpes simplex activity of 11 postbiotic samples (lysates or cell-free supernatants - CFS) produced during the fermentation of six candidate-probiotic Lactobacillus strains isolated from Bulgarian fermented milk products. MATERIALS AND METHODS: In vitro protocols for assessment of different LAB samples on the Herpes simplex virus type 1 (HSV-1) replication, adsorption and virucidal effects were applied using MDBK cells. RESULTS: Four of the studied LAB samples expressed a statistically significant inhibition of the replication of HSV-1. The highest selective index (79.75) was calculated for the post-metabolites of Lactiplantibacillus plantarum, followed by a high molecular fraction of cell-derived fragments of Limosilactobacillus fermentum culture (S6) (SI = 34.63), CFS from late exponential L. plantarum (SI = 28.26) and neutralized CFS from L. fermentum (SI = 28.11). Pronounced virucidal activities of the postbiotics S1, S11 (L. fermentum), S3 (L. plantarum) and S6 (L. fermentum) were recorded, too. The inhibitory effect of the majority of the samples on the stage of adsorption of the virus to MDBK cells was remarkable. In addition, almost all of the postbiotics exerted a protective effect on healthy cells and significantly reduced viral yield at subsequent infection. CONCLUSION: Pre-selected Lactobacillus strains demonstrated strain-specific effects against HSV-1. These postbiotics influence different stages of viral infection in cell cultures and their promising characteristics are currently evaluated.