OBJECTIVE To investigate the effect of betulin (BE) on the replication of rotavirus (RV) in vitro.METHODS ①MA104 cells were intervened with BE between 0.03125 and 64μmol·L-1 for 72 h,and MTT assay was used to detect the cell survival.② MA104 cells were infected with RV including Wa strains and SA-11 strains to establish a viral model.MA104 cells were divided into the cell control group,RV group and RV+BE groups.The cytopathic effect (CPE) method combined with MTT assay was used to detect the effect of BE on anti-RV adsorption,anti-RV biosynthesis and direct inhibition of RV.③The grouping was the same as in②,and RT-qPCR,Western blot and IF methods were used to detect the expression of RV structural protein VP6 after 24 h of BE incubation.④The grouping was the same as in②,and the ELISA kit was used to detect the concentrations of pro-inflammatory factors IL-6,IL-1β and TNF-α,anti-inflammatory factor IL-10 and type Ⅱ interferon IFN-γ in the cell supernatant after 24 h of BE incubation.⑤The grouping was the same as in②,and qPCR assay was used to detect the mRNA expression levels of Toll-like receptor 4 (TLR4),myeloid differentiation factor 88 (MYD88) and TNF receptor-associated factor 6 (TRAF6) after 24 h of BE incubation,Western blot assay was used to detect the expression levels of MYD88,IκBα,NF-κB p65,and p-NF-κB p65 after 24 h of BE incubation.RESULTS ① The maximum non-toxic concentration of BE towards MA104 cells was 1 μmol·L-1,and TC50 was 5.795 μmol·L-1.The concentrations of BE in the anti-RV experiments ranged from 0.03125μmol·L-1 to 1μmol·L-1.② In the anti-RV biosynthesis experiment,the inhibition rates of BE for RV-Wa between 0.0625 and 1 μmol·L-1 exceeded 50％,EC50 was 0.0485 μmol·L-1,and the value of TI was 119.48.The inhibition rates of BE for RV-SA-11 between 0.25 and 1 μmol·L-1 were above 50％,EC50 was 0.1226 μmol·L-1,and the value of TI was 47.27.In contrast,the effects of BE on anti-RV adsorption and direct inhibition of RV were not obvious.③ Compared with the RV group,BE inhibited the expression of VP6 (P＜0.01).④ Compared with the RV group,BE reduced the concentrations of IL-6,IL-1β and TNF-α(P＜0.01),but increased the concentrations of IL-10 and IFN-γ(P＜0.01).⑤Compared with the RV group,BE reduced the mRNA levels of TLR4,MYD88 and TRAF6 (P＜0.01),decreased the protein expression levels of MYD88 and p-NF-κB p65,and increased those of IκBα and NF-κB p65 (P＜0.01).CONCLUSION BE has anti-RV biosynthesis effect,and it may reduce inflammatory response caused by RV infection via TLR4/MYD88/NF-κB signaling pathway.

OBJECTIVE To investigate the effect of betulin (BE) on the replication of rotavirus (RV) in vitro.METHODS ①MA104 cells were intervened with BE between 0.03125 and 64μmol·L-1 for 72 h,and MTT assay was used to detect the cell survival.② MA104 cells were infected with RV including Wa strains and SA-11 strains to establish a viral model.MA104 cells were divided into the cell control group,RV group and RV+BE groups.The cytopathic effect (CPE) method combined with MTT assay was used to detect the effect of BE on anti-RV adsorption,anti-RV biosynthesis and direct inhibition of RV.③The grouping was the same as in②,and RT-qPCR,Western blot and IF methods were used to detect the expression of RV structural protein VP6 after 24 h of BE incubation.④The grouping was the same as in②,and the ELISA kit was used to detect the concentrations of pro-inflammatory factors IL-6,IL-1β and TNF-α,anti-inflammatory factor IL-10 and type Ⅱ interferon IFN-γ in the cell supernatant after 24 h of BE incubation.⑤The grouping was the same as in②,and qPCR assay was used to detect the mRNA expression levels of Toll-like receptor 4 (TLR4),myeloid differentiation factor 88 (MYD88) and TNF receptor-associated factor 6 (TRAF6) after 24 h of BE incubation,Western blot assay was used to detect the expression levels of MYD88,IκBα,NF-κB p65,and p-NF-κB p65 after 24 h of BE incubation.RESULTS ① The maximum non-toxic concentration of BE towards MA104 cells was 1 μmol·L-1,and TC50 was 5.795 μmol·L-1.The concentrations of BE in the anti-RV experiments ranged from 0.03125μmol·L-1 to 1μmol·L-1.② In the anti-RV biosynthesis experiment,the inhibition rates of BE for RV-Wa between 0.0625 and 1 μmol·L-1 exceeded 50％,EC50 was 0.0485 μmol·L-1,and the value of TI was 119.48.The inhibition rates of BE for RV-SA-11 between 0.25 and 1 μmol·L-1 were above 50％,EC50 was 0.1226 μmol·L-1,and the value of TI was 47.27.In contrast,the effects of BE on anti-RV adsorption and direct inhibition of RV were not obvious.③ Compared with the RV group,BE inhibited the expression of VP6 (P＜0.01).④ Compared with the RV group,BE reduced the concentrations of IL-6,IL-1β and TNF-α(P＜0.01),but increased the concentrations of IL-10 and IFN-γ(P＜0.01).⑤Compared with the RV group,BE reduced the mRNA levels of TLR4,MYD88 and TRAF6 (P＜0.01),decreased the protein expression levels of MYD88 and p-NF-κB p65,and increased those of IκBα and NF-κB p65 (P＜0.01).CONCLUSION BE has anti-RV biosynthesis effect,and it may reduce inflammatory response caused by RV infection via TLR4/MYD88/NF-κB signaling pathway.