Effect of Aminopterin on the Replication of the Murine Salivary Gland Virus

RECENT evidence has indicated that the synthesis of DNA viruses is prevented by specific DNA inhibitors while the synthesis of RNA viruses is not affected 1–3 . On this basis, therefore, experiments were undertaken to determine if aminopterin (4 amino-pteroylglutamic acid), a folic acid antagonist, would block the replication of the murine salivary gland virus (MSGV) in tissue culture. In the presence of adenine and glycine the antifolic drugs have been shown specifically to block the formation of DNA in mammalian cell cultures 3 . Under such conditions the antifolics will inhibit replication of DNA but not RNA viruses 2,3 .