# The Antiviral Potential of Probiotics--A Review on Scientific Outcomes
## 2 In Vitro Evidence of the Antiviral Activities of Probiotics
The antiviral effect of these four probioticic strains were further analyzed using different methods such as (i) exposing the cells with protein-based metabolites of the probioticic strain before viral infection (pre-treatment method), (ii) or after viral infection (post-treatment method) and (iii) the co-incubation method (the co-incubation of protein-based metabolites of the probioticic strain and virus and then the exposure of MA104 cells to the co-incubated mixture). The results indicated that the co-incubation method could protect the cells from viral infection effectively. Notably, _L. casei_ and _B. adolescents_ suppressed about 75 and 63% of infectivity, respectively. The results indicated that probioticic supplements could reduce the infectious rate of rotavirus [31]. Similarly, [PERSON] et al. [32] reported that the pre-exposure of probioticic strain _B. longum_ BORI to MA104 cells significantly reduced the viral infection, which was attributed to the ability of the probioticic to interfere with the interaction of viruses and host cells. Further, the anti-viral potential of the probioticic strain corresponded to the non-protein, low-molecular-weight bacterial compounds. The study suggested that the probioticic-derived compounds could help to manage the rotavirus infection (Table 1). \begin{table}
\begin{tabular}{c c c c c} \hline
**Probiotic(s)** & **Model** & **Anti-Viral** & **Findings** & **Ref. ** \\ \hline _Bifidobacterium indolescentis_ & & Human papillomavirus & & \\ SPM1005-A & & type 16 & & \\ \hline _Lactococcus lactis_ & & & & \\  & & kidney cells & & \\ \hline _B. adolescents_ & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & \\  & & &  
[PERSON] et al. [33] studied the antiviral activity of lactic acid bacteria (LAB) strains such as _L. rhamn_sous GG, _L. casei_ Shirota, _L. fermentatum_ (ACA-DC179, PCA142), _Lactobacillus pentosus_ PCA227, _L. plantarum_ (ACA-DC146, BFE5092, PCA236, PCS20, PCS22, PCS25 and PCS26), _Enterococcusecium_ (PCK38, BFE900, BFE2207 and PCD71), _Lactobacillus paracasei_ subsp. _tolerans_ ACA-DC4037 and _Lactobacillus gasseri_ PCA185) against the rotavirus RF strain and transmissible gastroenteritis coronavirus using the model (which are derived from healthy tissues) such as intestinal epithelial cell lines such as H4 (Human origin), PSI (Pig origin), GIE (Goat origin) and monocyte/macrophages such as TLT (Human origin), PoM2 (Pig origin) and pig enterocytes (CLAB). The induction of the release of free radicals (reactive oxygen species; ROS), the percentage of surviving cell lines and the ability of LAB to attach to the cell lines were used as a measure to determine the antiviral activity of the LAB strains. The release of ROS (H\({}_{2}\)O\({}_{2}\) and NO\({}^{-}\)) from cell lines was increased up to 50% when co-cultured with LAB strains, but this induction was probiotic strain-specific and cell line-specific. The percentage of surviving virus infected-cell lines increased by up to 80%, which depended on the LAB strains and cell lines. The ability of LAB strains to attach to the cell lines was LAB-specific. _E. facecium_ PCD71, _L. plantarum_ ACA-DC146 and _L. paracasei_ ACA-DC4037 exhibited a high adhesion capability with cell lines. _L. casei_ Shirota showed the potent antiviral activity against transmissible gastroenteritis coronavirus and _L. plantarum_ PCA236 showed the potent antiviral activity against both transmissible gastroenteritis coronavirus and rotavirus. The antiviral activity of the other tested strains was dependent on the type of cell lines, virus and LAB strains. The study demonstrated that the LAB strains have the antiviral potential in vitro, which warrants further studies [33].