In cultured Drosophila melanogaster cells, vesicular stomatitis virus (VSV) established a persistent, noncytopathic infection. No inhibition of host protein synthesis occurred even though all cells were initially infected. No defective interfering particles were detected, which would explain the establishment of the carrier state. In studies of the time course of viral protein synthesis in Drosophila cells, N, NS, and M viral polypeptides were readily detected within 1 h of infection. The yield of G protein and one of its precursors; G1, was very low at any time of the virus cycle; the released viruses always contained four to five times less G than those produced by chicken embryo cells, whatever the VSV strain or serotype used for infection and whatever the Drosophila cell line used as host. Actinomycin D added to the cells before infection enhanced VSV growth up to eight times. G and G1 synthesis increased much more than that of the other viral proteins when the cells were pretreated with the drug; nevertheless, the released viruses exhibited the same deficiency in G protein as the VSV released from untreated cells. Host cell control on both G-protein maturation process and synthesis at traduction level is discussed in relation to G biological properties.