# The Antiviral Potential of Probiotics--A Review on Scientific Outcomes
## 2 In Vitro Evidence of the Antiviral Activities of Probiotics  
_Bifidobacterium adolescents_ SPM1005-A treatment reduced the expression of an oncogene in Human papillomavirus (HPV) type 16 infected SiHa cells. The suppression of E6 and E7 mRNA was observed after probiotic treatment, which was not associated with the morphology of cells and does not exhibit any cytotoxicity. The result suggests that SPM1005-A could be used to prevent HPV-associated cervical cancer [26]. The pre-treatment of feline calicivirus with a cell-free bacterial medium filtrate (CBMF) and a bacterial cell suspension (BCS) of _Lactococcus lactis_ subsp. _lactis_ LM0230 reduced the feline calicivirus titer (in terms of log\({}_{10}\) tissue culture infectious dose (TCID\({}_{50}\))) in Crandell-Reese feline kidney cells. About 1.3 and 1.8 TCID\({}_{50}\) were observed in the viral infected cells when the virus was pre-treated with CBMF and BCS, respectively. A significant decrease in feline calicivirus titer was not obtained by the pretreatment of the virus with CBMF (adjusted to pH 7). When the kidney cells are co-treated with feline calicivirus and either CBMF (adjusted to pH 7) or BCS, the antiviral activity was increased significantly. There was no cytotoxicity in the cells (uninfected with virus) treated with higher dilutions of CBMF, and with both undiluted and diluted BCS [27]. _B. adolescents_ inhibited the multiplication of murine norovirus-1 on RAW 264.7 ( murine macrophage cell line) cells. The genome copies of murine norovirus-1 collected from the infected RAW 264.7 cells were not reduced, indicating that _B. adolescents_ does not inhibit the murine norovirus-1 from binding to the RAW 264.7 cells. However, the binding of human norovirus GI.1 virus-like particles to human intestinal epithelial cell lines (Caco-2 and HT-29 cells) was reduced by _B. adolescents_. Similarly, the binding of human norovirus GI.4 virus-like particles to Caco-2 cells was not reduced, while the binding of human norovirus GII.4 virus-like particles to HT-29 cells was reduced. Therefore, the antiviral effect of _B. adolescents_ against murine norovirus-1 and human norovirus virus-like particles might be based on a different mechanism [28]. The _Bifidobacterium longum_ subsp. _infantis_ CECT7210 treatment reduced the replication (~36% reduction in infectious foci) and infection rate (~48% reduction in infectious foci) of rotavirus Wa in the MA-104 and HT-29 cell lines. The co-culturing of CECT7210 and cell lines effectively reduced the viral infectivity [29]. The cell-free metabolites of _Lactobacillus casei_ CMPUJ 415, _Lactobacillus fermentutum_ CMPUJ 413, _Bifidobacterium bifidum_ and _B. adolescentis_ DSM 20083 were evaluated for the anti-rotavirus activity. The treatment of metabolites of _L. casei_ CMPUJ 415 and _B. adolescents_ DSM 20083 effectively reduced the production of NSP4 protein and the release of Ca\({}^{2+}\) in rotavirus-infected MA104 cells. The results suggested that probiotic bacterial metabolites could suppress the impact of the rotavirus infection by reducing the production of the NSP4 protein and regulate the liberation of Ca\({}^{2+}\)[30]. Viable probioticic strains such as _B. adolescents_ (DSM 20083), _Bifidobacterium breve_ (ATCC 15700), _B. bifidobacterium dentum_ (DSM 20084), _Bifidobacterium lactis_ (Lafti B94-DSL), _Lactobacillus acidophilus_ (Lafti L10-DSL), _L. casei_ (Lafti L26-DSL), _L. fermentutum_ (ATCC 9338), _Lactobacillus plantarum_ (CECT 220) and _Lactobacillus rhamnus_ (ATCC 7469) were screened for in vitro anti-rotavirus activity in MA104 (embryonic Riesus monkey kidney cell line) cells. The percentage of viral infection was reduced by the _L. casei_, _L. fermentutum_, _B. adolescents_ and _B. bifidum_ strains in MA104 cells compared to that of the other viable probioticic strains.