Haemophilus parasuis invades porcine brain microvascular endothelial cells.
Haemophilus parasuis, an important swine pathogen, is the aetiological agent of Glässer's disease. It is responsible for cases of polyserositis, meningitis and pneumonia in young pigs. To date, 15 serotypes have been described, although several non-typable isolates are frequently recovered from diseased animals. The pathogenesis of H. parasuis infection is poorly understood. To cause meningitis, H. parasuis would have to cross the blood-brain barrier (BBB), composed of brain microvascular endothelial cells (BMEC). The objective of this study was to investigate the ability of H. parasuis to interact with porcine brain microvascular endothelial cells (PBMEC). It was demonstrated that the serotype 5 reference strain of H. parasuis, Nagasaki (originally recovered from a case of meningitis), was able to adhere at very high levels to and, most importantly, invade PBMEC. These capacities were confirmed by electron microscopy. Actinobacillus pleuropnemoniae serotype 7 (strain WF 83), used as negative control, was not able to adhere to or invade PBMEC. Comparisons of the levels of adhesion and invasion by several H. parasuis field strains from different serotypes isolated from cases of either meningitis or pneumonia showed that isolates of serotypes 4 and 5 had a higher invasion capacity than isolates belonging to other serotypes. Inhibition studies demonstrated that PBMEC invasion by H. parasuis required rearrangement of actin microfilaments and microtubular cytoskeletal elements but not active bacterial DNA, RNA or protein synthesis. Characterization studies demonstrated that proteinaceous invasin(s) does not seem to play a major role in entry of H. parasuis into PBMEC. Intracellular viable H. parasuis were found in PBMEC up to 6 h after antibiotic treatment. Even at high bacterial doses, H. parasuis was not toxic to PBMEC. In swine, the invasion of endothelial cells of the BBB may play an important role in the pathogenesis of meningitis caused by H. parasuis.
Vanier
Ghyslaine
G
Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
Szczotka
Anna
A
Canadian Research Network on Bacterial Pathogens of Swine, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
Friedl
Peter
P
Institute für Biochemie, Technische Hochschule Darmstadt, Petersenstrasse 22, 64287 Darmstadt, Germany.
Lacouture
Sonia
S
Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
Jacques
Mario
M
Canadian Research Network on Bacterial Pathogens of Swine, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.|Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
Gottschalk
Marcelo
M
Canadian Research Network on Bacterial Pathogens of Swine, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.|Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
D000199:Actins / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D001921:Brain / Q000098:blood supply; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism / Q000382:microbiology; D006192:Haemophilus Infections / Q000382:microbiology*; D044137:Haemophilus parasuis / Q000502:physiology*; D013045:Species Specificity; D013552:Swine
D000199:Actins