Restricted replication of vesicular stomatitis virus in T lymphocytes is coincident with a deficiency in a cellular protein kinase required for viral transcription.

Vesicular stomatitis virus (VSV) fails to replicate in mouse T lymphocytes unless the cells have been mitogenically stimulated with concanavalin A (Con A). We have examined the possibility that the failure of VSV to replicate in unstimulated T lymphocytes can be attributed to a deficiency in a host protein kinase which activates the viral P protein by phosphorylation, thus rendering it transcriptionally competent. Soluble extracts were prepared from purified mouse T lymphocytes, with or without prior treatment with Con A. The ability of these extracts to phosphorylate bacterially synthesized P protein of two VSV serotypes was measured in vitro. Activity of the protein kinase on the P proteins of the Indiana or New Jersey serotypes of VSV increased, on average 2.4- and 2.1-fold respectively, after treatment of the cells with 3 micrograms/ml Con A. Higher concentrations of Con A induced proportional increases (up to 10-fold) in the activity of the host protein kinase. Activities of the kinase phosphorylating the P protein in separate populations of CD4- and CD8-containing murine T lymphocytes increased similarly on mitogenic activation. No biochemical or immunological differences were observed between the T cell protein kinase and the previously characterized protein kinase (casein kinase II) from BHK-21 cells. The activity of the kinase that phosphorylates the P protein did not vary in CV-1 cells on treatment with alpha- or gamma-interferon, both of which inhibited VSV replication. Similarly, casein kinase II activities in Raji and SIRC cells, which do not normally support VSV growth, were the same as in BHK-21 cells. Thus restriction of VSV replication in these cells, in contrast to T lymphocytes, was not associated with a deficiency in the host casein kinase II activity.