Evaluation of inactivated vaccines against equine group A rotaviruses by use of a suckling mouse model

Abstract Background Equine group A rotaviruses (RVAs) cause diarrhea in suckling foals. The dominant RVAs circulating among horses worldwide, including Japan, are G3P[12] and/or G14P[12] genotypes. Inactivated vaccines containing a G3P[12] RVA are commercially available in some countries for prevention of diarrhea caused by equine RVAs. However, there is no reported evidence whether vaccines containing a G3P[12] RVA are effective against G14P[12] RVAs or whether using a G14P[12] RVA results in a more effective vaccine. This study used a suckling mouse model to evaluate the effectiveness of inactivated vaccines containing G3P[12] (G3 vaccine) or G14P[12] (G14 vaccine) RVAs against G3P[12] and G14P[12] RVAs. Methods Female mice were inoculated twice with G3 or G14 vaccines, and were then mated. After parturition, suckling mice were challenged with one of either two G3P[12] RVAs, two G14P[12] RVAs, or one G13P[18] RVA. After virus inoculation, suckling mice were observed for diarrhea, and the incidence rates of diarrhea in the vaccinated groups were compared with those in the non-vaccinated groups. Results Following G3P[12] RVA challenge, suckling mice in the G3 and G14 vaccinated groups had significantly lower rates of diarrhea incidence than did those in the non-vaccinated group, and the rates in the G3 vaccinated group tended to be lower than in the G14 vaccinated group. Following G14P[12] RVA challenge, suckling mice in the G14 vaccinated group had significantly lower rates of diarrhea incidence than did those in the non-vaccinated and G3 vaccinated groups. The G3 and G14 vaccines did not reduce the rate when challenged with the G13P[18] RVA. Conclusion The mouse model showed that the G3 and G14 vaccines were both effective against G3P[12] RVAs, and that the G14 vaccine was effective against G14P[12] RVAs. These results suggest that at least a G14 RVA strain should be included in as a vaccine strain.