MAPPING OF THE LINEAR ANTIGENIC DETERMINANTS FROM THE LEISHMANIA-INFANTUM HISTONE H2A RECOGNIZED BY SERA FROM DOGS WITH LEISHMANIASIS

Antibodies reacting against the H2A histone protein were frequently ob served in the sera from dogs naturally infected with the protozoan par asite Leishmania infantum. Using synthetic peptides covering the compl ete sequence of the protein we have identified the amino terminal regi on, comprising from amino acids 1 to 20, and the carboxyl terminal reg ion, comprising from amino acids 106 to 132, as conforming the antigen ic determinants of the protein. Those regions, exposed in the nucleoso me surface, are highly divergent in sequence relative to the mammalian H2A histones. The anti-H2A histone antibodies present in the sera of these dogs specifically recognize the L, infantum H2A histone and they do not react with mammalian histones. The present data indicate that, in spite of the evolutionary conservation of the H2A histone protein among eukaryotic organisms, the humoral response against this protein during natural infection is specifically triggered by the parasite pro tein antigenic determinants.