Enterococcus faecalis endocarditis severity in rabbits is reduced by IgG Fabs interfering with aggregation substance.
PLoS One
; 5(10)2010 Oct 04.
Article
em En
| MEDLINE
| ID: mdl-20957231
ABSTRACT
BACKGROUND:
Enterococcus faecalis is a significant cause of infective endocarditis, an infection of the heart endothelium leading to vegetation formation (microbes, fibrin, platelets, and host cells attached to underlying endothelial tissue). Our previous research determined that enterococcal aggregation substance (AS) is an important virulence factor in causation of endocarditis, although endocarditis may occur in the absence of AS production. Production of AS by E. faecalis causes the organism to form aggregates through AS binding to enterococcal binding substance. In this study, we assessed the ability of IgGs and IgG Fabs against AS to provide protection against AS+ E. faecalis endocarditis. METHODOLOGY/PRINCIPALFINDINGS:
When challenged with AS+ E. faecalis, 10 rabbits actively immunized against AS+ E. faecalis developed more significant vegetations than 9 animals immunized against ASâ»E. faecalis, and 9/10 succumbed compared to 2/9 (p<0.005), suggesting enhanced aggregation by IgG contributes significantly to disease. IgG antibodies against AS also enhanced enterococcal aggregation as tested in vitro. In contrast, Fab fragments of IgG from rabbits immunized against purified AS, when passively administered to rabbits (6/group) immediately before challenge with AS+E. faecalis, reduced total vegetation (endocarditis lesion) microbial counts (7.9 x 106 versus 2.0 x 105, pâ=â0.02) and size (40 mg versus 10, pâ=â0.05). In vitro, the Fabs prevented enterococcal aggregation. CONCLUSIONS/SIGNIFICANCE:
The data confirm the role of AS in infective endocarditis formation and suggest that use of Fabs against AS will provide partial protection from AS+E. faecalis illness.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fragmentos Fab das Imunoglobulinas
/
Enterococcus faecalis
/
Endocardite
Limite:
Animals
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article