Isolation and characterisation of Plasmodium falciparum (Welch, 1897) solub
le antigens from infected patient plasma, Western blotting, thermal stabili
ty and ELISA assays using hyperimmune IgG-antimalaria antibodies was the ma
in objective of this work. A circulating antigen of approximately Mr 33-35
kDa with good specificity and antigenicity, in the plasma of malarial patie
nts was shown. Heating at 100 degreesC did not destroy its antigenicity. Wh
en fractions highly enriched in the 33-35 kDa proteins were used in ELISAs,
a seroreactivity in plasma obtained from primary-infected individuals was
found. Controls from normal patients were always negative. The antigenic ch
aracteristics suggest that it may be included within the group of new descr
ibed Plasmodium soluble antigens.