EFFECTS OF PLANT-DERIVED POLYSACCHARIDES ON MURINE CYTOMEGALOVIRUS AND ENCEPHALOMYOCARDITIS VIRUS-INFECTIONS IN MICE

Polysaccharides from three plant species, Astragalus brachycentrus (AV 222), Astragalus echidnaeformis (AV224) and Sterculia urens (AV223), w hich are devoid of in vitro antiviral activity, were evaluated in mous e models of murine cytomegalovirus and encephalomyocarditis virus infe ctions. AV223 and AV224 were very potent agents, protecting mice from mortality at intraperitoneal doses between 3.2 and 100 mg kg(-1) day(- 1) treatments. Treatment with compounds needed to be started one day p rior to virus inoculation for maximum protective benefit. Treatments s tarting after virus inoculation were ineffective. No detectable toxici ty was apparent in mice treated with up to 100 mg of each polysacchari de per kg of body weight. Interferon was not detected in mouse sera fr om polysaccharide-treated mice, suggesting a different mode of immune- enhancement may be responsible for the antiviral effects observed.