FIG. 3.

The 14 unique PvMSP-1 block 6 sequences found in P. vivax isolates circulating in the study area in 1999 and 2004 to 2005 and their absolute frequencies. Two of the sequences (sequences I and VII, corresponding to 36.2% of all block 6 sequences) match sequences found in recombinant antigens used in serology (BR07 and BP39, respectively). The remaining block 6 antigens, Belém and BP1, are quite similar to sequences I (97.5% amino acid identity) and XII (98.1% amino acid identity), respectively.