[Single - nucleotide polymorphisms of artemisinin resistance - related and genes in Bioko Island, Equatorial Guinea from 2018 to 2020].

OBJECTIVE

To investigate the prevalence of single nucleotide polymorphisms (SNPs) of artemisinin resistance-related and genes in isolates from Bioko Island, Equatorial Guinea, so as to to provide baseline data for the formulation of malaria control strategies in Bioko Island.

METHODS

A total of 184 clinical blood samples were collected from patients with malaria in Bioko Island, Equatorial Guinea from 2018 to 2020, and genomic DNA was extracted. The and gene SNPs of were determined using a nested PCR assay and Sanger sequencing, and the gene sequences were aligned.

RESULTS

There were 159 wild-type isolates (88.83%) from Bioko Island, Equatorial Guinea, and 6 SNPs were identified in 20 -mutant isolates (11.17%), in which 4 non-synonymous mutations were detected, including E1516G, K1520E, D1525E, E1528D. There was only one gene mutation site in 19 -mutant isolates (95.00%), in which non-synonymous mutations accounted for 68.42% (13/19). D1525E and E1528D were identified as major known epidemic mutation sites in the gene associated with resistance to artemisinin-based combination therapies (ACTs). At amino acid position 1525, there were 178 wild-type isolates (99.44%) and 1 mutant isolate (0.56%), with such a mutation site identified in blood samples in 2018, and at amino acid position 1528, there were 167 wild-type isolates (93.30%) and 12 mutant isolates (6.70%). The proportions of wild-type isolates were 95.72% (134/140), 79.25% (126/159) and 95.83% (161/168) in the target amplification fragments of the three regions in the gene (-inner1, -inner2, -inner3), respectively. There were 16 different SNPs identified in all successfully sequenced isolates, in which 7 non-synonymous mutations were detected, including S160N, K199T, A475V, S508G, I511M, L595F, and Y603H. There were 7 out of 43 -mutant isolates (16.28%) that harbored only one gene mutation site, in which non-synonymous mutations accounted for 28.57% (2/7). For the known delayed clearance locus S160N associated with ACTs, there were 143 wild-type (89.94%) and 16 -mutant isolates (10.06%).

CONCLUSIONS

Both and gene mutations were detected in isolates from Bioko Island, Equatorial Guinea from 2018 to 2020, with a low prevalence rate of gene mutation and a high prevalence rate of gene mutation. In addition, new mutation sites were identified in the (E1504E and K1520E) and genes (A475V and S508G).