Phylogenetic analysis of lack gene sequences for 22 Chinese Leishmania isolates

The phylogenetic relationships between Chinese Leishmania strains were investigated using lack (Leishmania homolog of receptors for activated protein kinase C) gene sequences, and the power of this gene was assessed for understanding the epidemiology and population genetics of Leishmania.

The lack gene sequences from Leishmania isolates were sequenced after polymerase chain reaction (PCR) amplification. Sequence alignment was performed and a phylogenetic tree was created using the MEGA 5.0 software program.

Sequences of 850 bp were analyzed for each of the Leishmania strains collected from different locations in China, and minor differences in sequences were noted between the strains. Four distinct groups formed according to differences in the sequences of the lack gene. Group I consisted of 12 isolates from Shandong, Xinjiang, Gansu and Sichuan. These strains are part of the Leishmania donovani complex and are pathogenic to humans and canines. Group II included six isolates from Xinjiang and a reference strain, Leishmania turanica. Group III contained two isolates (one from a sand fly in Xinjiang and one from a rodent in Inner Mongolia) and they were identified as Leishmania gerbilli. Finally, group IV contained a strain from a sand fly in Xinjiang and a strain from a lizard in Inner Mongolia, and these strains were found to be Sauroleishmania.

The Chinese Leishmania isolates formed four groups based on differences in the sequences of the lack gene, and this result is consistent with previous studies. Phylogenetic analysis suggests that the Leishmania isolates from China are more complicated than previously thought. There is consensus between genetic clustering and identification using classical methods, which means that the lack gene yields polymorphic information that could be used for genotyping Leishmania isolates.