Prevention of Rotavirus Diarrhea in Suckling Rats by a Specific Fermented Milk Concentrate with Prebiotic Mixture

Abstract

Several microbial modulatory concepts, such as certain probiotics and prebiotics, confer protection against gastrointestinal infections, among which is acute diarrhea caused by the rotavirus (RV). Other microbiota modulators, such as postbiotics, produced during fermentation, might also have the potential to counteract RV infection. In light of this, a fermented milk, made by using Bifidobacterium breve C50 (BbC50) and Streptococcus thermophilus 065 (St065) with a prebiotic mixture-short chain galactooligosaccharides/long chain fructooligosaccharides (scGOS/lcFOS 9:1)-with potential to impact the intestinal microbiota composition was tested. An RV infected rat model was used to evaluate the amelioration of the infectious process and the improvement of the immune response induced by the fermented milk with prebiotic mixture. The dietary intervention caused a reduction in the clinical symptoms of diarrhea, such as severity and incidence. Furthermore, a modulation of the immune response was observed, which might enhance the reduction of the associated diarrhea. In addition, the fermented milk with prebiotic mixture was able to bind the virus and reduce its clearance. In conclusion, the postbiotic components in the fermented milk in combination with the prebiotics used here showed protective properties against RV infection.

Keywords: fermented formula; postbiotic; prebiotic; probiotic; rotavirus.

Figure 1

Body weight (g) from the Reference (REF), the Rotavirus (RV) and the Fermented Milk + Prebiotic (FM + P) groups throughout the first 14 days of the study. The period includes before and after virus inoculation on day 7 (dashed vertical line). Results are expressed as mean values ± SEM (n = 21 animals/group). No statistical differences were found.

Figure 2

Diarrhea incidence and severity from the Reference (REF), the Rotavirus (RV) and the Fermented Milk + Prebiotic (FM + P) groups. Percentage of diarrheic animals (% DA) before (A) and after subtracting the basal values due to intrinsic aspects of the treatment (B); percentage of diarrheic feces (% DF) before (C) and after subtracting the basal values due to intrinsic aspects of the treatment (D); severity of diarrhea in a scale from 0 to 4 before (E) and after (F) subtracting the basal values due to intrinsic aspects of the treatment. DI ≥ 2 indicates diarrheic feces. Values are means (n = 21 animals/group) ± SEM. Statistical significance is explained in the text.

Figure 3

Overall diarrhea incidence and severity AUCs. AUC of the incidence expressed as percentage of diarrheic animals (daAUC) (A), or of diarrheic feces (dfAUC) (B), and AUC of the severity pattern (sAUC) (C). Results are shown for animals from the Rotavirus (RV) group (black bars), Fermented Milk + Prebiotic (FM + P) group (grey bars) and Fermented Milk + Prebiotic group after subtracting the basal values due to intrinsic aspects of the treatment (nFM + P) (grey striped bars). As Reference animals did not develop diarrhea, they had AUC values equal to 0 (data not shown). Results are expressed as the overall incidence pattern corresponding to all animals together or the mean of each individual severity pattern from the 21 animals/group. Standard errors are shown in Figure 3C. Statistical significance: # p < 0.05 vs. RV.

Figure 4

Diarrhea and infection indicators from the Reference (REF), the Rotavirus (RV) and the Fermented Milk + Prebiotic (FM + P) groups. Mean fecal weight through the early post-infection period (days 8−11) (A); mean fecal pH during same diarrhea period (B); and viral shedding on day 1 post-infection (DPI) (C). Results are shown for animals from the REF group (white bars), RV group (black bars) and FM + P group (grey bars). Results are expressed as mean and SEM of samples or determinations derived from 21 animals/group. Statistical significance: * p < 0.05 vs. REF, # p < 0.05 vs. RV.

Figure 5

Specific anti-RV antibodies in serum (A) and intestinal wash (B) from 14- and 21-day-old rats. The values of each isotype in the Rotavirus (RV) group on day 14 are considered as 100 AU, and the results for the Rotavirus (RV) group and for the Fermented Milk + Prebiotic (FM + P) group on day 21 have been proportionally adjusted for each isotype. Results are expressed as mean and SEM (n = 9−12 animals/group) in AU/mL. # p < 0.05 vs. RV group.