In vitro cultivation and immunostaining of Lawsonia intracellularis strains

The aim of the study was to implement in vitro cultivation of L. intracellularis strains using ATCC 55783 and vaccine strains, and McCoy cells (ATCC CRL-1696). The infection was monitored by daily observations under phase contrast microscope. Indirect immunostaining using monoclonal antibody was also performed. Large number of S-shaped, moving bacteria were found in the cell medium in cultures infected with ATCC 55783 and vaccine strain. Immunostaining revealed a high number of multiple cell-associated or intracellular red stained bacteria in the infected cultures. This study describes for the first time in vitro cultivation of L. intracellularis in Poland, which creates further perspective for more advanced research on this bacterium.