In vitro study of the effect of a probiotic bacterium Lactobacillus rhamnosus against herpes simplex virus type 1

background: due to the emergence of drug resistance in herpes simplex virus type 1 (hsv-1), researchers are trying to find other methods for treating herpes simplex virus type 1 infections. probiotic bacteria are effective in macrophage activation and may have antiviral activities. objective: this study aimed at verifying the direct effect of lactobacillus rhamnosus, a probiotic bacterium, in comparison with escherichia coli, a non-probiotic one, on hsv-1 infection, and determining its effect on macrophage activation for in vitro elimination of hsv-1 infection. methods: the above bacteria were introduced into hsv-1 infected vero cells, and their effects were examined using both mtt and plaque assay. to determine macrophage activation against in vitro hsv-1 infection, j774 cells were exposed to these bacteria; then, macrophage viability was examined with the mtt method, and tumor necrosis factor alpha (tnf-α), interferon-gamma (ifn-γ), and nitric oxide (no) assessments were performed using the elisa method. results: a significant increased viability of macrophages was observed (p < 0.05) in the presence of lactobacillus rhamnosus before and after hsv-1 infection when compared with escherichia coli as a non-probiotic bacterium. however, tumor necrosis factor α concentration produced by escherichia coli-treated j774 cells was significantly higher than lactobacillus rhamnosus-treated j774 cells (p < 0.05). interferon-gamma and no production were not different in the groups treated with escherichia coli or with lactobacillus rhamnosus. conclusion: the results of this study indicate that lactobacillus rhamnosus enhances macrophage viability for hsv-1 elimination and activation against hsv-1 more effectively, when compared with non-probiotic escherichia coli. it also seems that receptor occupation of macrophage sites decreases hsv-1 infectivity by both of the studied bacteria.