Rat dorsal root ganglia neurons as a model for Listeria monocytogenes infections in culture

Neurotropism of Listeria monocytogenes was studied in rat dorsal root gangl ia (DRG) and hippocampal neurons in culture. Using a system in which the DR G neurons can grow relatively free from other cells, it was observed that s uch DRG neurons, in contrast to hippocampal neurons, can be effectively inf ected by L. monocytogenes. The bacteria aligned along DRG axons, but not al ong hippocampal neurites. A mutant deficient in internalin, a protein requi red for entry into E-cadherin-expressing cells, did not interact with DRG n eurons. Axonal migration of bacteria was studied in the DRG neurons grown i n a double-chamber system, where either the neurites or the nerve cell bodi es were exposed to the bacteria. The data suggest that L. monocytogenes can infect both axons and DRG nerve cell bodies, and that the bacteria can mig rate in a retrograde as well as anterograde direction. These results suppor t the notion that L. monocytogenes can spread via primary sensory neurons t o the central nervous system. Infection of DRG primary sensory neurons, as employed in the present study, provides a model for analysis of bacterial a nd neuronal factors of importance for neurovirulence of L. monocytogenes.