Detection of cell detachment activity induced by Moraxella bovis.
OBJECTIVE
To characterize the effect that filtrate obtained from cultures of Moraxella bovis has on cultured corneal epithelial cells and other types of cultured mammalian cells.


METHODS
Cultured hamster corneal epithelial cells, bovine epithelial cells, and several transformed cell lines exposed to culture filtrate from a pathogenic isolate of M bovis.


METHODS
Moraxella bovis was cultured, and bacteria were removed by filtration. The resulting bacterial culture filtrate was incubated with various types of cultured cells, and effects of the filtrate on detachment of various mammalian cell types was quantified by the use of neutral red dye. Additionally, bacterial culture filtrate was treated with protease inhibitors as well as trypsin and heat prior to incubation with cultured mammalian cells.


RESULTS
Bacterial culture filtrate of M bovis caused all types of cultured cells to detach from each other and from the substrate, with the maximal effect evident 2 hours after initiating incubation. Detached cells were alive, and detachment was reversible. Serine protease inhibitors (phenylmethylsulfonylfluoride and alpha2-macroglobulin) inhibited cell detachment attributable to bacterial culture filtrate. Heating and treatment with trypsin also inhibited cell detachment.


CONCLUSIONS
Moraxella bovis produces a soluble factor that causes reversible detachment of cultured cells. This activity may play a role in the pathogenesis of infectious bovine keratoconjunctivitis.
Marrion
R M
RM
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia 65211, USA.
Riley
L K
LK
D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology* / Q000382:microbiology; D006224:Cricetinae; D004847:Epithelial Cells / Q000166:cytology / Q000382:microbiology; D006358:Hot Temperature; D016955:Moraxella bovis / Q000472:pathogenicity*; D011480:Protease Inhibitors / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism
D011480:Protease Inhibitors; D014357:Trypsin