Detection of Genetic Mutations Associated with Drug Resistance in Imported Plasmodium falciparum

Objective: To investigate the mutation of genes associated with drug resistance (Pfcrt, Pfmdr1, Pfdhfr and K13） in imported Plasmodium falciparum in Shandong Province. Methods: Blood was collected from 94 falciparum malaria cases who returned from Africa in 2014. Genomic DNA for P. falciparum was extracted from the blood samples and nested PCR was performed using primers specifically designed for Pfcrt, Pfmdr1, Pfdhfr and K13. The PCR products were sequenced. Gene mutations were analyzed by sequence alignment. Results: The 94 imported cases were from 18 African countries. Nested PCR was successful on DNA from all the blood samples except for Pfcrt amplification in one sample. Sequence analysis revealed three types of mutations Pfcrt K76T （36.6%, 34/93）, Pfmdr1 N86Y （21.3%, 20/94）, and Pfdhfr S108N （98.9%, 93/94） （χ2=127.5， P<0.05）. K13 C580Y mutation was not found. Co-occurrence of K76T, N86Y, and S108N was found in 6 blood samples （6.5%）, which were imported from Liberia（2）, Angola（1）, Equatorial guinea（1）, Congo（1）, and Guinea（1）. Co-occurrence of K76T and S108N mutations was found in 28 samples（30.1%）, and that of N86Y and S108N in 14 samples （15.1%）. Forty-four samples（47.3%） harbored S108N mutation only, and one sample was null for any of the mutations. Conclusion: There are mutations in Pfcrt, Pfmdr1, and Pfdhfr in imported Plasmodium falciparum in Shandong Province. No mutation was found for the K13 gene.