Abortive infection of a rabbit cornea cell line by vesicular stomatitis virus: conversion to productive infection by superinfection with vaccinia virus.

An abortive infection of a rabbit cornea cell line (RC-60) by vesicular stomatitis virus (VSV), yielding less than 1 PFU/cell, was converted to a productive infection, yielding 1,900 PFU/cell, when cells were superinfected with vaccinia. Studies on the synthesis of VSV-directed RNA in RC-60 cells suggest that the abortive infection by VSV alone may be due in part to (i) a limited production of 40S virion RNA and (ii) a markedly reduced activity of virion-bound transcriptase activity in RC-60 cells compared to the activity in mouse L cells, a permissive host for VSV. No recognizable VSV structures, except a small amount of viral core structures, were produced by the abortive infection. In contrast, double infection of RC-60 cells with VSV and vaccinia in the presence of hydroxyurea resulted in the production of infective B particles of VSV. Although the function supplied by vaccinia responsible for the productive replication of VSV in double infected RC-60 cells has not been identified, metabolic inhibitor studies indicate that continuous vaccinia-dependent RNA synthesis is required for maximal production of infective VSV. The possibility is considered that vaccinia may supply a product or function required for VSV replication which is ordinarily supplied by the host but which is lacking in RC-60 cells.