Fossil peccaries of Late Pleistocene/Holocene (Cetartiodactyla,Tayassuidae) from underwater caves of Serra da Bodoquena (Mato Grosso do Sul State,Brazil)

New records of Catagonus stenocephalus and Tayassu pecari are reported from the karst of Serra da Bodoquena, located at a south-western portion of Brazil near the border with Paraguay. Skull and lower jaw fragments at different stages of mineralisation were retrieved from two limestone underwater caves, Japonês and Nascente do Formoso, associated with clay and sand deposits with no retrievable stratigraphy. C14 dating of fossil mammals from these caves was attempted, but so far no success was achieved, but the inferred age for the associated paleofauna of these caves is Late Pleistocene and Holocene. The morphology of these fossil peccaries, from the most south-western known population in Brazil, is detailed and paleoecological implications are considered.     

Plasmodium falciparum: restricted polymorphism of T cell epitopes of the circumsporozoite protein in Brazil.

We examined the extent of variation of the 3' region of the circumsporozoite gene among Plasmodium falciparum isolates through amplification of a selected DNA fragment followed by DNA sequencing. A total of 32 isolates were analyzed, of which 24 were from Amazon endemic areas in Brazil and 8 from widely separated geographical regions in the world. Among Brazilian isolates only 2 variants were detected: 19 displayed the same sequence of strain 7G8 whereas the 4 remaining isolates differed from the 7G8 strain at five nucleotide positions which also led to amino acid changes. Variation was restricted to one of the T-helper epitopes while the sequence identified as a cytotoxic T cell epitope was conserved in all Brazilian isolates. P. falciparum samples from other geographical regions in the world showed sequences distinct from those of Brazilian isolates. However, some constancy could be observed within that variation. For instance, the most frequent nucleotide substitutions, from A and C at nucleotide positions 1015 and 1024, were the same in all isolates.     

Cellular immune response of humans to the circumsporozoite protein of Plasmodium vivax.

The cellular immune response to the circumsporozoite (CS) protein of Plasmodium vivax of individuals from malaria-endemic areas of Brazil was studied. We examined the in vitro proliferative response of the peripheral blood mononuclear cells (PBMC) of 22 individuals when stimulated with a CS recombinant protein (rPvCS-2) and two other synthetic peptides based on the sequence of the P. vivax CS protein. Seven of the individuals from malaria-endemic area displayed an antigen-specific in vitro proliferative response to the recombinant protein PvCS-2 and one out of 6, proliferative response to the peptide 308-320. In contrast, none of the individuals displayed a proliferative response when stimulated with the D/A peptide which represent some of the repeated units present in this CS protein. Our study, therefore, provides evidence for the presence, within the major surface antigen of P. vivax sporozoites, of epitopes capable to induce proliferation of human PBMC.