Effect of P-fluorophenylalanine on the Synthesis of Vaccinia Virus.

The effect of the amino acid analog FPA on vaccinia virus replication in HeLa cells was investigated, By varying the dose of FPA or the time after infection at which the analog was added to cultures, it was possible to inhibit differentially the synthesis of viral components in vaccinia-infected cells. When suflicient FPA was added t,o GUItures at the t,ime of infection, the synthesis of viral DNA, NP anbigen, infectious virus, and HA was inhibited. The inhibition of synthesis of LS antigen under all conditions studied was only partial. FPA added to cultures at 6 or more hours post-in feetion did not inhibit production of viral antigens or infectious virus. The inhibition was reversed by P,4 added with the FPA, but PA added at later times was progressively less effective in restoring the ability of inhibited infected cultures to produce virus. The proportion of nuclei incorporating t.hymidine-H3 was decreased in cultures infect.ed with vaecinia virus. This decrease was nut seen in cultures receiving FPB at the t,ime of infection.