Differentiation of Trypanosoma cruzi I subgroups through characterization of cytochrome b gene sequences.
To identify and characterize chilean samples of Trypanosoma cruzi and their association with hosts, the first 516 bp of the mitochondrial cytochrome b gene were sequenced from eight biological samples, and phylogenetically compared with other known 20 American sequences. The molecular characterization of these 28 sequences in a maximum likelihood phylogram (-lnL = 1255.12, tree length = 180, consistency index = 0.79) allowed the robust identification (bootstrap % > 99) of three previously known discrete typing units (DTU): DTU IIb, IIa, and I. An apparently undescribed new sequence found in four new chilean samples was detected and designated as DTU Ib; they were separated by 24.7 differences, but robustly related (bootstrap % = 97 in 500 replicates) to those of DTU I by sharing 12 substitutions, among which four were nonsynonymous ones. Such new DTU Ib was also robust (bootstrap % = 100), and characterized by 10 unambiguous substitutions, with a single nonsynonymous G to T change at site 409. The fact that two of such new sequences were found in parasites from a chilean endemic caviomorph rodent, Octodon degus, and that they were closely related to the ancient DTU I suggested old origins and a long association to caviomorph hosts.
Spotorno O
Angel E
AE
Programas de Genética Humana, ICBM, Facultad de Medicina, Universidad de Chile, Independencia 1027, Clasificador No. 7, Casilla 70005, Santiago 7, Chile. aspotorn@med.uchile.cl
Córdova
Luis
L
Solari I
Aldo
A
D000818:Animals; D002677:Chile; D045303:Cytochromes b / Q000235:genetics*; D030541:Databases, Genetic; D050259:Genes, Mitochondrial; D017125:Genes, Protozoan; D006801:Humans; D046329:Octodon / Q000469:parasitology; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014349:Trypanosoma cruzi / Q000145:classification* / Q000235:genetics
D015800:Protozoan Proteins; D045303:Cytochromes b