Invasion of endothelial cells by systemic and nasal strains of Haemophilus parasuis

Haemophilus parasuis is a respiratory commensal in healthy piglets but can also produce invasive disease and meningitis which requires the ability to cross the blood-brain barrier This study determined the capacity of well-characterised virulent and non-virulent strains of H parasuis as well as other field strains to adhere to and invade PBMEC/C1-2 endothelial cells Virulent strains were derived from systemic lesions conformed to the systemic clade on multilocus sequence typing (MIST) and were phagocytosis- and serum-resistant Non-virulent strains were derived from the nostrils of healthy piglets belonged to the nasal clade on MIST and were phagocytosis- and serum-sensitive Virulent strains mostly were more invasive than non-virulent strains although one virulent strain was unable to invade Invasion of endothelial cells is a virulence mechanism of H parasuis that may be related to the ability of some strains to cause meningitis (C) 2009 Elsevier Ltd All rights reserved