Antiviral activity of certain isatinisothiosemicarbazones against Mengo and vaccinia virus infections in mice.

Among eleven isatinisothiosemicarbazones (IITS) examined only 1-ethylisatin-S-n-butylisothiosemicarbazone (ZIMET 189/69) proved to be significantly effective against lethal Mengo and neurovaccinia virus-induced encephalitis in mice when administered subcuaneously (s.c.) in doses of 1 mmole/kg body weight per day. With peroral (p.o.) administration all the drugs failed to prevent mortality in Mengo virus-infected mice. Against this virus ZIMET 189/69 was effective over a concentration range from 0.6-1.4 mmoles/kg per day producing a plateau effect at doses greater than 1 mmole/kg. With Mengo virus maximum protective response was seen in intraperitoneally (i.p.) or intranasally (i.n.) infected mice when treatment was begun at the time of virus inoculation and continued, once daily for a period of at least four consecutive days. Delayed initiation of treatment failed to protect Mengo virus-infected mice but was effective in vaccinia virus-infected mice.