Effects of Plant-Derived Polysaccharides on Murine Cytomegalovirus and Encephalomyocarditis Virus Infections in Mice

Abstract

Polysaccharides from three plant species, Astragalus brachycentrus (AV222), Astragalus echidnaeformis (AV224) and Sterculia urens (AV223), which are devoid of in vitro antiviral activity, were evaluated in mouse models of murine cytomegalovirus and encephalomyocarditis virus infections. AV223 and AV224 were very potent agents, protecting mice from mortality at intraperitoneal doses between 3.2 and 100 mgkg−1 day−1 treatments. Treatment with compounds needed to be started one day prior to virus inoculation for maximum protective benefit. Treatments starting after virus inoculation were ineffective. No detectable toxicity was apparent in mice treated with up to 100 mg of each polysaccharide per kg of body weight. Interferon was not detected in mouse sera from polysaccharide-treated mice, suggesting a different mode of immuno-enhancement may be responsible for the antiviral effects observed.