OBJECTIVETo investigate the effect of Chinese herbal medicine Xin-kang oral liquid on interferon (IFN)-induction and its antiviral activity in Coxsackievirus B3 virus strain (CVB3) infected mice.

METHODSThe Xin-kang oral liquid was given orally to mice two days prior to the challenge of CVB3 virus to induce myocarditis. Two dosages of Xin-kang oral liquid crude herbal medicine 30 g x kg(-1) x d(-1) and 12 g x kg(-1) x d(-1) were given to the mice of different treatment groups respectively, sterilized water was given to the mice of virus control group. IFN-alpha 10(6) U x kg(-1) x d(-1) S.C was given to the infected mice as positive drug control group. The mice were sacrificed on 5th, 10th and 20th day of infection for evaluation, the levels of serum interferon (IFN) were titrated with vesicular stomatitis virus (VSV) and cardiac tissue was fixed and sectioned. The quantitative histological changes at various stages of myocarditis were observed.

RESULTSIn the infected mice fed with 30 g x kg(-1) x d(-1) or 12 g x kg(-1) x d(-1) of Xin-kang oral liquid orally for 5, 10 and 20 days, the mean titer of serum IFN of Xin-Kang oral liquid treated group was markedly higher (29.3 U/0.1 ml) than that of virus control group (12.6 U/0.1 ml). The level of serum IFN in IFN treated positive control mice was lower than that of Xin-kang treatment groups. The histological examination showed extensive myocardial necrosis and cellular infiltration in virus control group, but necrosis and cellular infiltration were less severe in Xin-kang treatment goups of mice. It is demonstrated that there were close correlation between the degree of myocardial lesions and the level of IFN-induction in treated mice.

CONCLUSIONXin-kang oral liquid could facilitate the induction of endogenous interferon that exerted its antiviral activity in CVB3 infected mice. This can help us to understand better the mechanism of anti-CVB3 effect of Xin-Kang oral liquid.