Psoralen treatment of adenovirus particles eliminates virus replication and transcription while maintaining the endosomolytic activity of the virus capsid

Adenovirus entry into its host cell transiently permeabilizes the cell allowing the coentry of reagents such as DNA. We compare here adenovirus inactivation with β-propiolactone and several psoralen derivatives, seeking reagents that disrupt the viral genome without impairing the viral entry functions. No virus replication can be detected after 8-methoxypsoralen (8-MOP) modification. Viral transcription is not detectable by Northern analysis, and reverse transcriptase/PCR analysis demonstrates at least a 1000-fold decrease in viral transcription after 8-MOP treatment. Using [³H]8-MOP, the psoralen is found to enter the virus capsid and react throughout the viral genome, with approximately one psoralen modification per 100 bp of viral DNA. This inactivated adenovirus allows us to deliver DNA to target cells without interference from adenovirus gene expression or replication. Furthermore, we can now study the host cell response to adenovirus entry without the complications of adenovirus gene expression.