J. Hellman et al., ANTISERUM AGAINST ESCHERICHIA-COLI J5 CONTAINS ANTIBODIES REACTIVE WITH OUTER-MEMBRANE PROTEINS OF HETEROLOGOUS GRAM-NEGATIVE BACTERIA, The Journal of infectious diseases, 176(5), 1997, pp. 1260-1268
The binding of Ige in antiserum to Escherichia coli J5 to the surface
of Enterobacteriaceae and to cell wall fragments released from serum-e
xposed bacteria was studied in a search for potentially protective epi
topes other than lipopolysaccharide (LPS). IgG titers to multiple hete
rologous gramnegative smooth bacteria increased following incubation o
f the bacteria in serum and decreased following absorption with serum-
exposed heterologous bacteria. IgG eluted from absorbing bacteria boun
d to at least three conserved bacterial outer membrane proteins (OMPs)
, but not LPS, as assessed by immunoblotting. The same OMPs were prese
nt in LPS-containing macromolecular cell wall fragments released by in
cubation of heterologous gram-negative bacteria in human serum. Part o
f the protection offered by J5 antiserum could be from binding of IgG
to conserved OMPs at the bacterial surface or to OMPs in cell-wall fra
gments released from dying bacteria.