GENE-EXPRESSION AND CYTOPATHIC EFFECT OF VACCINIA VIRUS-INACTIVATED BY PSORALEN AND LONG-WAVE UV-LIGHT

Induction of the cytopathic effect (CPE) in cells infected with poxvir us seems ubiquitous in that it has been associated with all different strains and preparations of poxviruses, regardless of the replicating status of these viruses. The study of the mechanisms by which CPE is i nduced by nonreplicating poxviruses is hampered by the lack of ang non cytopathic mutant strains and preparations, In this paper, we report o n the patterns of gene expression and induction of CPE bg vaccinia vir uses treated bg limited cross-linking with psoralen and long-wave UV l ight (PLWUV). We show that treatment of cell-free virus with PLWUV cou ld inactivate viral replication without abolishing the ability of the virus to infect cells. Viral transcription as indicated by reporter ge nes was generally enhanced and prolonged under early viral promoters a nd abolished under late promoters, Furthermore, increasing the levels of cross linking with PLWUV resulted in a decrease and abolishment of viral expression of a large reporter gene and a concomitant loss of th e induction of CPE. Cells infected with such a virus were able to expr ess the reporter genes and proliferate, The generation of nonreplicati ng and noncytopathic recombinant vaccinia viruses may help in studies of the mechanisms of CPE induction by poxvirus and may facilitate the use of poxviral vectors in broader areas of research and clinical appl ications.