Dendrimer-enabled DNA delivery and transformation of Chlamydia pneumoniae

Abstract The chlamydiae are important human pathogens. Lack of a genetic manipulation system has impeded understanding of the molecular bases of virulence for these bacteria. We developed a dendrimer-enabled system for transformation of chlamydiae and used it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumoniae , which lacks any plasmids. The plasmid was cloned into modified yeast vector pEG(KG) and the clone complexed to polyamidoamine dendrimers, producing 50–100 nm spherical particles. HEp-2 cell cultures were infected with C. pneumoniae strain AR-39. Twenty-four hours later, medium was replaced for 3 hours with dendrimer-plasmid complexes, then removed and the medium replaced. Cultures were harvested at various times post-transformation. Real-time PCR and RT-PCR of nucleic acids from transformed cultures demonstrated plasmid replication and gene expression. The cloned plasmid was replicated and expressed in transformants over 5 passages. This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies. From the Clinical Editor This team of investigators developed a dendrimer-enabled system for transformation of chlamydiae and successfully utilized it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumonia . This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies.