Anti-Influenza Activity of Lactobacillus Johnsonii Isolated from the Bamboo Rat (Rhizomys Sinensis)

Abstract

Influenza virus infections remain a serious threat to global public health, causing considerable morbidity and mortality each year. The growing interest in probiotics as natural antiviral agents provides new opportunities for developing alternative or adjunctive strategies against influenza infection. In this study, we investigated the anti-influenza virus activity of Lactobacillus Johnsonii (L. johnsonii) isolated from the bamboo rat (Rhizomys sinensis). The isolate was identified by 16S rRNA gene sequencing and biochemically characterized using the API 50 CHL kit. Antiviral activity was evaluated through both pre- and post-treatment approaches using broth suspensions, cell-free supernatants (CFS), bacterial pellets, and heat-killed preparations. Cytopathic effect (CPE) inhibition and MTT assays were employed to assess cell viability and antiviral efficacy. The pre-treated broth suspension exhibited the highest inhibitory activity, achieving 68% inhibition, while the post-treated suspension showed 61.3%. Similarly, CFS displayed 62.6% and 52.2% inhibition, bacterial pellets 56% and 47.9%, and heat-killed bacteria 47% and 46.3% inhibition in pre- and post-treatment assays, respectively. Notably, the pre-treatment approach consistently demonstrated stronger antiviral effects than post-treatment, suggesting a preventive mechanism of action. These results indicate that L. johnsonii exerts significant inhibitory effects against the influenza virus, potentially through the secretion of antiviral metabolites or modulation of host cellular responses. These findings provide preliminary evidence that L. johnsonii isolated from the bamboo rat possesses notable anti-influenza virus activity and warrants further investigation to elucidate its underlying mechanisms and potential applications.