G. Morales et al., MAPPING OF THE ANTIGENIC DETERMINANTS OF THE LEISHMANIA-INFANTUM GP63PROTEIN RECOGNIZED BY ANTIBODIES ELICITED DURING CANINE VISCERAL LEISHMANIASIS, Parasitology, 114, 1997, pp. 507-516
The gp63 gene encoding the major surface antigen of Leishmania infantu
m has been cloned and sequenced. In spite of the overall sequence homo
logy with the gp63 genes from other Leishmania species, particularly w
ith the constitutively expressed Leishmania chagasi Gp63 gene, the car
boxy-terminal ends of these genes are clearly divergent (62% homology)
. To study the prevalence of anti-gp63 antibodies in the sera from dog
s with visceral leishmaniasis, a recombinant L. infantum gp63 protein
was expressed in Escherichia coli. It was found that 100% of the sera
from these dogs recognized the recombinant gp63 protein, suggesting th
at it must function as a potent B cell immunogen during natural canine
visceral leishmaniasis. However, heterogeneity in the level of respon
se was observed. Fine mapping of the antigenic determinants was perfor
med by means of 6 overlapping subfragments of the gp63 protein and by
the use of a library of synthetic peptides. The data showed that there
is some degree of immunological restriction in the recognition of the
protein since reactivity was observed preferentially against the most
divergent region. The epitope mapping of this region showed 2 immunod
ominant peptides the response to which seems to be preferentially of t
he IgG2 type.