Abstract: AIM: To further understand the genetic variation among Leishmania species in China by karyotype analysis. METHODS: DNA karyotypes of 16 Leishmania isolates in China were analyzed by pulsed field gel electrophoresis, and 5 different species of WHO reference Leishmania isolates were used in comparison. RESULTS: Chromosomal DNAs under 2 200 kb were resolved under pulsed field gel electrophoresis conditions. All the 16 isolates, even isolates in the same endemic area exhibited different chromosomal DNA banding patterns. The size variation in the chromosomal DNAs was evident particularly in chromosomes between 225 and 850 kb. Large-sized DNAs of more than 850 kb were more conserved than smaller-sized DNAs among 16 Leishmania isolates. DNA karyotype analysis showed: ① The 14 isolates belonging to L. infantum /donovani complex presented similar but different karyotype; the DNA banding patterns of those from the same endemic area were more similar than different areas, as seen in isolates of KS22, KS23, KS26, KS27, KS28, KS29, KS213 and KS216 in Kashi region, Xingjiang and in isolates of Liu and Xu in Karamay region, Xingjiang. The 771 isolates separated from sandfles in Bachu, Xingjiang exhibited 26 DNA bands, being more than the average 19- 21 DNA bands of other isolates separated from human patie ts. ② R12 and R 20 isolates having been previously named after L. turanica and L. gerbilli exhibited much more similar karyotypes, which were obviously different from other tested isolates and the five WHO reference isolates. CONCLUSION: ① Apparent in traspecific karyotype variations among L. donovani/infantum complex isolates in China, the more similarities in DNA banding patterns, the closerrelationship between the isolates. ② Eco-geographical isolation and sandfly vector have contributed to the heterogeneity of L.infantum /L.donovani complex in China. ③ The isolates R 12 and R20 tend to belong to one species/two closely-related species.

Key words: Leishmania, pulsed field gel electrophoresis, molecular karyotype