Human microvascular endothelial cell toxicity caused by Brazilian purpuric fever-associated strains of Haemophilus influenzae biogroup aegyptius.
An in vitro cytotoxicity model that uses an immortalized human microvascular endothelial cell line (HMEC-1) differentiates Brazilian purpuric fever (BPF)-associated Haemophilus influenzae biogroup aegyptius (HAE) strains from non-BPF-associated HAE strains. Toxic strains produced a characteristic HMEC-1 phenotype at an MOI of < 1 bacterium/1000 tissue culture cells (TCC). Nontoxic strains required MOIs of > 1000 bacteria/TCC to produce an observable effect. The cytotoxic phenotype was characterized by the presence of large clumps of HMEC-1 cells, which detached from the monolayer within 48 h of inoculation by HAE cells. The cytotoxic phenotype was observed with 100% of BPF-associated HAE (40/40) and 14% of non-BPF-associated HAE (8/57; P < .001). The ability to study a BPF-associated phenotype in vitro using human microvascular cells should enhance our knowledge of BPF pathogenesis.
Weyant
R S
RS
Emerging Bacterial and Mycotic Disease Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
Quinn
F D
FD
Utt
E A
EA
Worley
M
M
George
V G
VG
Candal
F J
FJ
Ades
E W
EW
D002460:Cell Line; D004730:Endothelium, Vascular / Q000382:microbiology*; D006192:Haemophilus Infections / Q000473:pathology*; D006193:Haemophilus influenzae / Q000472:pathogenicity*; D006801:Humans; D066298:In Vitro Techniques