# The Antiviral Potential of Probiotics--A Review on Scientific Outcomes
## 4 Clinical Studies on the Antiviral Potential of Probiotics
The total cold symptoms score and pharyngeal symptoms were also reduced during the probiotic treatment. Moreover, the probiotic supplementation improved the B lymphocytes count in healthy subjects. The results suggested that the consumption of _L. plantarum_ HEAL 9 and _L. paracasei_ 8700:2 could prevent or nullify the severity of the common cold [55]. The co-adjuvant ability of _Lactobacillus fermentutum_ CECT5716 for an anti-influenza vaccine has been reported by [PERSON] et al. [59]. The healthy subjects (\(n=25\); 10 females, 15 males) were orally supplemented with _L. fermentutum_ (\(10^{10}\) CFU per day) for 28 days in addition to an anti-influenza vaccination (vaccination on day 14). Two weeks after vaccination, the concentrations of natural killer cells, T-helper type 1 cytokine concentrations, antigen specific IgA and total IgM were increased significantly compared to the placebo control (\(n=25\); 9 females, 16 males). The vaccination boosted immunity, whereas the probiotic supplementation further improved the immune system. The incidence of influenza-like illness was much lower in the probiotic-supplemented group during the five months after vaccination. The results suggested that the consumption of probiotics could enhance systemic immunity against viral infection [56]. The effect of the supplementation of fermented milk containing _L. casei_ 431 on the immune response to influenza vaccination in healthy adults (18-60 years old) was investigated. The consumption of probiotic milk (\(10^{9}\) CFU per day) for 42 days did not affect the immune response in healthy subjects, whereas the duration of upper RTIs was reduced. There were no notable changes in the incidence and severity of the infection. The results suggested that _L. casei_ 431 could reduce the number of episodes of upper RTIs in healthy adults [57]. The supplementation of _Bifidobacterium longum bv. infants_ CCUG 52486 (\(10^{9}\) CFU per day) and gluco-oligosaccharide (8 g per day) for eight weeks increased the total antibody titers, influenza-vaccine-specific IgA, IgM and IgG levels in both adult and older subjects. The antibody titer and vaccine-specific immunoglobulin levels were slightly lower in older subjects compared to adults. The senescent (CD28\({}^{-}\)CD57\({}^{+}\)) helper T cells and plasma anti-CMV IgG levels were higher at baseline in the intervention group, which biased the outcome of the study. The study suggested that aging is associated with antibody response to influenza vaccination and the symbiotic supplementation did not improve the situation. Moreover, the study evidenced that the randomization of study subjects is a critical step in randomized, double-blinded, placebo-controlled pre-clinical studies [58]. [PERSON] et al. [59] studied the effect of _Clostridium butylcium_, or _Bacillus subtilis_, and _Enterococcus facicum_ supplementation on microbial diversity and preventing the risk of secondary infection in patents who are suffering from an H7N9 influenza viral infection. The results showed that the probiotic intervention improved the diversity and evenness of microbiota. The supplementation of _C. butylcium_ did not prevent the incidence of secondary infection, but the _B. subtilis_ and _E. facicum_ intervention reduced the secondary infection in H7N9-infected patients. The authors claimed that _B. subtilis_ and _E. facicum_ supplementation could ameliorate secondary infection in H7N9-infected patients. The antiviral potential of GandeenBC\({}^{30}\) (_Bacillus coagul_s GBI-306086) has been evaluated in healthy subjects in terms of immune activation. The healthy subjects were supplemented with \(2\times 10^{9}\) CFU of probiotics for 30 days. The changes in the levels of TNF-\(\alpha\) and IFN-\(\gamma\) have been determined at baseline and after 30 days of study. The results showed that the level of TNF-\(\alpha\) was increased upon adenovirus and influenza A (H3N2 Texas strain) exposures, whereas there were no significant changes in the IFN-\(\gamma\) level. There were no adverse effects during the study.