M. Ho et al., SPECIFICITY AND FUNCTIONAL-ACTIVITY OF ANTI-BURKHOLDERIA PSEUDOMALLEIPOLYSACCHARIDE ANTIBODIES, Infection and immunity, 65(9), 1997, pp. 3648-3653
The lipopolysaccharide (LPS) of Burkholderia pseudomallei, the causati
ve agent of melioidosis, consists of two O-antigenic polysaccharides d
esignated O-PS I and O-PS II. In this study, the O-PS specificity and
functional activity of a protective polyclonal antiserum and an immuno
globulin M (IgM) monoclonal antibody were determined, The polyclonal a
ntiserum recognized both Q-PS I and O-PS II, while the monoclonal anti
body was O-PS II specific, Both mediated phagocytic killing of B, pseu
domallei by polymorphonuclear leukocytes, Patients acutely infected wi
th B. pseudomallei also produced antibodies to the two O-PSs, but thes
e antibodies were not produced by asymptomatic individuals from an are
a of endemicity who were seropositive by an indirect hemagglutination
test using sonicated heat-killed whole organisms as antigen, IgM antib
odies were detected only in patients,vith localized infection, Ige ant
ibodies were detected in all acutely infected patients, but there was
no significant difference in antibody levels among patients with local
ized infection, patients who survived septicemic illness, and patients
who died from septicemic illness, Further analysis of the Ige respons
e revealed production of IgG1 and IgG2 antibodies by all patient group
s, while an IgG3 response was seen only in survivors of septicemic inf
ection. IgG4 was not detectable even when a fivefold-lower serum dilut
ion was used, Patient sera also mediated phagocytic killing by polymor
phonuclear leukocytes, and the killing effect was enhanced by compleme
nt. These results suggest that antibodies to the LPS O-polysaccharides
of B, pseudomallei are protective by promoting phagocytic killing. Th
e antibodies develop during human infection and may facilitate clearan
ce of the organisms, as seen in a diabetic rat model of B, pseudomalle
i infection.