IN VIVO ANTIVIRAL ACTIVITY OF 1,3-BIS(2-CHLOROETHYL)-1-NITROSOUREA

A prolongation in the lives of Swiss mice inoculated intracerebrally with lymphocytic choriomeningitis virus (LCM) was observed after treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A variety of treatment schedules, including therapy once or twice daily up to 17 days and single treatments at various times after virus inoculation, were employed. Virus titers ranging to greater than 10(4) were detected in the blood and brains of surviving drug-treated animals. In three comparative studies in which different treatment schedules were used, BCNU was shown to exert a protective effect approximately equal to that of methotrexate in LCM virus-infected mice. Tests were also carried out to investigate the activity of BCNU in mice experimentally infected with eastern equine encephalomyelitis (EEE) virus, western equine encephalomyelitis virus, Semliki Forest (SF) virus, herpes simplex virus, influenza virus strain PR8, vaccinia virus strain WR, Rous sarcoma virus, Friend leukemia virus (FLV), and poliovirus. Slight increases in life span were observed in the treated EEE, SF, and influenza PR8 virus-infected animals. Significant reduction in splenomegaly in FLV-infected animals treated with BCNU was demonstrated. The possible mechanisms of LCM virus inhibition by BCNU, on the basis of these and other studies, were postulated to be either specific antiviral activity or inhibition of "lethal" immune response to the LCM virus. Each of these postulates is discussed.

THE USE OF ACETYLETHYLENEIMINE IN THE PRODUCTION OF INACTIVATED FOOT-AND-MOUTH DISEASE VACCINES

Suspensions of FMD virus treated with 0·05% formalin at 26° C. for periods up to 144 hr. remained infective for cattle, although the infectivity could not be detected in the presence of aluminium hydroxide. Infectivity was detected in similar virus suspensions which had been treated with 0·05% AEI at 37° C. for 8 hr. but not in suspensions treated for 12 hr.

Vaccines prepared from these suspensions were antigenically potent and serum neutralization tests demonstrated the development and regression of serum antibody. The AEI vaccines were at least as potent as the corresponding formalin vaccines.

RUBELLA VIRUS: INHIBITION IN VITRO BY AMANTADINE HYDROCHLORIDE

Amantadine (or 1-adamantanamine) hydrochloride, a compound reported to be active against influenza viruses and Sendai virus, inhibited the growth of rubella virus in tissue culture. The antiviral activity appears at an early phase of the infection and is not due to direct inactivation of the virus.

THERAPEUTIC ANTIVIRAL ACTION OF 5-TRIFLUOROMETHYL-2'-DEOXYURIDINE IN HERPES SIMPLEX KERATITIS

5-Trifluoromethyl-2'-deoxyuridine (F(3)TDR) has potent therapeutic antiviral activity in herpes simplex infection of the rabbit cornea with strains of herpes virus both sensitive and resistant to 5-iodo-2'-deoxyuridine, and in corneal infection with vaccinia. 5-Trifluoromethyl uracil is not therapeutically active in herpetic keratitis.

INTERFERON-LIKE ACTIVITY OF EXTRACTS OF HUMAN SPLEEN

Extracts of human splenic tissue were found to resemble interferon in (a) their physicochemical properties, and (b) their mode of action when tested in vivo in the rabbit, using vaccinia as the challenge virus. The methods used to obtain (1) the crude extract and (2) a partially purified final fraction are described. The latter was found to be non-dialysable, stable over a pH range of 2-11, and relatively heat resistant. On analysis it appeared to be, or was associated with, a glycoprotein.