Cellular Morphology and Immunologic Properties of Escherichia coli Treated with Antimicrobial Antisense Peptide Nucleic Acid

Background & Objectives: Antisense peptide nucleic acids (PNA) that target growth essential genes show potent bactericidal properties without cell lysis. We considered the possibility that whether PNA treatment influence the bacteria total nucleic acids content and apply approach to develop a new delivery system to Dendritic cells (DCs). DCs are the most potent antigen presenting cells in the immune systems. Since the uptake of bacteria by DC is a necessary step for generation of effective DNA vaccine, we studied the uptake efficiency of PNA treated bacteria by DCs. Material & Methods: Total nucleic acids of anti- acyl carrier protein (acpP) peptide-PNA treated Escherichia coli Hb101 containing plasmid have been isolated. In addition, peripheral blood monocytes have been purified using mouse anti- cluster of differentiated (CD14) coated magnetic beads and then culture in presence of growth factors. Generated DCs have been assessed for their ability of uptake of flurescein isothiocyanate (FITC) - labeled peptide-PNA treated bacteria and heat inactivated by flow cytometry. Results: The preparation of total nucleic acid from peptide-PNA treated showed five distinct bands which correspond to chromosomal DNA, plasmid DNA, 23S ribosomal RNA (rRNA), 16S rRNA and mixture of small RNA. DCs incubated with FITC- labeled peptide-PNA treated and heat inactivated bacteria showed almost equal fluoresence intensity. Conclusion: Peptide–PNA treatment bacteria are intact and do not appear to alter cell barriers and nucleic acid content. They can be taken up by DCs efficiently. These finding may confirm new application for peptide-PNA in immunology and DNA vaccine.