Global transcriptional responses of Pseudomonas aeruginosa to phage PRR1 infection.

The infectious cycles of viruses are known to cause dramatic changes to host cell function. The development of microarray technology has provided means to monitor host cell responses to viral infection at the level of global changes in mRNA levels. We have applied this methodology to investigate gene expression changes caused by a small, icosahedral, single-stranded-RNA phage, PRR1 (a member of the Leviviridae family), on its host, Pseudomonas aeruginosa, at different times during its growth cycle. Viral infection in this system resulted in changes in expression levels of <4% of P. aeruginosa genes. Interestingly, the number of genes affected by viral infection was significantly lower than the number of genes affected by changes in growth conditions during the experiment. Compared with a similar study that focused on the complex, double-stranded-DNA bacterial virus PRD1, it was evident that there were no universal responses to viral infection. However, in both cases, translation was affected in infected cells.

Complete genome sequence of the broad host range single-stranded RNA phage PRR1 places it in the Levivirus genus with characteristics shared with Alloleviviruses.

Single-stranded RNA (ssRNA) bacteriophages of the family Leviviridae infect gram-negative bacteria. They are restricted to a single host genus. Phage PRR1 is an exception, having a broad host range due to the promiscuity of the receptor encoded by the IncP plasmid. Here we report the complete genome sequence of PRR1. Three proteins homologous with those of other ssRNA phages, i.e., maturation, coat, and replicase proteins, were identified. A fourth protein has a lysis function. Comparison of PRR1 with other members of the Leviviridae family places PRR1 in the genus Levivirus with some characteristics more similar to those of members of the genus Allolevivirus.