Infectivity of Novel Intracellular Bacteria for Eukaryotic Cells

Abstract

Three different cell lines, Dictyostelium discoideum, Acanthamoeba polyphaga, and U937 cells, were infected with a novel bacterium, Candidatus Berkiella cookevillensis (CC99). The level of infectivity within the cells was observed using Giemsa staining combined with microscopic observation. The first goal of the study was to determine if the bacteria would infect the cells of the model organism D. discoideum, so that future studies could be done on pathways of infection. The second goal of the study was to determine the ability of the bacteria to pass between different cell types or hosts. CC99 was passed between A. polyphaga cells, from A. polyphaga cells to U937 cells, and between U937 cells. The bacteria were observed in the nucleus of D. discoideum cells by 24 hours post-infection, and after 48 hours all nuclei were infected. The CC99 bacterium was shown to be capable of passing between A. polyphaga cells, from A. polyphaga cells to U937 cells, and between U937 cells. The nuclei of A. polyphaga cells became fully infected by 48 hours post-infection, while the nuclei of the U937 cells did not show significant levels of infection in the nuclei until 72 hours post-infection.