Bovine rotavirus (BRV) is one of the common gastrointestinal diseases that can occur in calves, causing severe diarrhea. This study was conducted to investigate the effects of oral administration of single-domain antibodies, single variable domain of heavy chain of HCAb (VHH), on the prevention and treatment of rotavirus-induced diarrhea in calves. Thirty calves were divided into five experimental groups (negative control, positive control, group A, group B and group C). Except for the negative control group, the experimental groups were inoculated with BRV on the 4th day after birth. The VHH supplementation groups were fed with a substitute milk containing different concentrations of VHH (1%, 2.5% and 7.5%). Changes in body weight, clinical symptoms, serum antibodies, and virus detection in feces were observed for a total of 10 days in each experimental group. The results showed a higher survival rate in the VHH supplementation groups compared to the positive control group. Clinical symptoms caused by rotavirus were alleviated in the VHH supplementation groups. The detection rate of rotavirus in feces also decreased. Gross findings indicated that the severity of disease in the VHH supplementation groups was milder than that in the positive control group. Therefore, VHH could be proposed as a useful alternative for the prevention and treatment of rotavirus-induced diarrhea in calves.

Probiotics, such as Lactobacillus spp. and Bifidobacterium spp. are reported to have the multiple potential health benefits including blocking gastroenteric pathogens, reduce gut permeability, enhancing immune response and anti-viral effects. In this study, we explored whether LR211 and BL205, 206 exert on MCP-1 and IL-8 chemokines responses in rotavirus infected vero cells. And we investigated anti-rotaviral activity of Lactobacillus spp. and Bifidobacterium spp. isolated against rotavirus by plaque assay. As a results, all of them were not toxic to vero cells. Three probiotics, BL205, 206 and LR211, increased release of MCP-1 and IL-8 in Wa rotavirus infected vero cells compared to control. This anti-viral effects of LR211 and BL205, 206 can be explained that they modulate immune response by inducing MCP-1 and IL-8 chemokines.