A recombinant vaccinia virus infects Xenopus melanophores

A recombinant vaccinia virus was employed to demonstrate infection of cultured Xenopus laevis melanophores. The recombinant virus contains one copy each of the Escherichia coli lac Z and human growth hormone genes under the transcriptional control of two separate viral promoters. Western blot analysis and in situ staining revealed the dependency of beta-galactosidase production in infected Xenopus cells on time and multiplicity of infection (MOI). Western blot analysis was used to demonstrate the production of a 65 kD vaccinia late protein and its variation over time and with MOI. When virus preparations from infected Xenopus cells were attempted, no amplification of virus was observed and only a minute portion of the original innoculum was recovered. We therefore propose an abortive infection of Xenopus pigment cells by vaccinia virus: The amphibian cells allow for the synthesis of viral proteins, but not for the efficient replication of competent virus. The findings have implications not only for our understanding of the virus/host interaction, but also for the efficient expression of exogenously introduced genes in cultured Xenopus melanophores.