NATURAL-RESISTANCE OF BALB C MICE TO HERPES-SIMPLEX VIRUS-TYPE-1 INTRAPERITONEAL INFECTION IS ABROGATED BY A PLANT-EXTRACT WITH IN-VITRO ANTI-HERPES ACTIVITY/

Adult BALB/c mice, genetically resistant to HSV-1 i.p. infection, were inoculated intraperitoneally with 1000 PFU of HSV-1 and treated by th e same route with four consecutive doses of Melia azedarach L. aqueous green leaves extract (MA) each containing 80 antiviral units against HSV-1 replication in Vero cells. Mice were injected 1 day and 6 h befo re infection and 1 and 2 days after infection. Mortality among untreat ed 45 day old female and male mice was around 35% for both sexes, wher eas MA treatment increased mortality to 95% in females and to 50% in m ales. Virus was isolated from brains of treated animals. Enhanced susc eptibility to HSV-1 infection upon treatment with MA extract was also observed in male mice 25 days old, before hormonal maturation, indicat ing that the impairment of natural resistance to HSV-1 infection is se x-linked, Treatment with MA extracts did not interfere with establishe d specific immune protection nor with the induction of immune response to HSV-1, Virus was recovered from peritoneal exudate cells only in M A-treated animals. The abrogation of natural resistance of inbred mice to i,p, HSV-1 infection by pretreatment and early administration of t he plant extract indicates that the in vivo expression of immunomodula ting activities on receptor cells interfered with its potent antiviral activity displayed in vitro against HSV-1 replication. (C) 1998 John Wiley & Sons, Ltd.