Abstract:
Background: Plasmodium falciparum delayed clearance with the use of artemisinin-based combination therapy
(ACTs) has been reported in some African countries. Single nucleotide polymorphisms (SNPs) in two genes, P.
falciparum adaptor protein complex 2 mu subunit (pfap2mu) and ubiquitin specific protease 1 (pfubp1), have been
linked to delayed clearance with ACT use in Kenya and recurrent imported malaria in Britain. With over 12 years of
ACT use in Ghana, this study investigated the prevalence of SNPs in the pfap2mu and pfubp1 in Ghanaian clinical
P. falciparum isolates to provide baseline data for antimalarial drug resistance surveillance in the country.
Methods: Filter paper blood blots collected in 2015–2016 from children aged below 9 years presenting with
uncomplicated malaria at hospitals in three sentinel sites Begoro, Cape Coast and Navrongo were used. Parasite
DNA was extracted from 120 samples followed by nested polymerase chain reaction (nPCR). Sanger sequencing
was performed to detect and identify SNPs in pfap2mu and pfubp1 genes.
Results: In all, 11.1% (9/81) of the isolates carried the wildtype genotypes for both genes. A total of 164 pfap2mu
mutations were detected in 67 isolates whilst 271 pfubp1 mutations were observed in 72 isolates. The majority of
the mutations were non-synonymous (NS): 78% (128/164) for pfap2mu and 92.3% (250/271) for pfubp1. Five unique
samples had a total of 215 pfap2mu SNPs, ranging between 15 and 63 SNPs per sample. Genotypes reportedly
associated with ART resistance detected in this study included pfap2mu S160N (7.4%, 6/81) and pfubp1 E1528D
(7.4%, 6/81) as well as D1525E (4.9%, 4/81). There was no significant difference in the prevalence of the SNPs between
the three ecologically distinct study sites (pfap2mu: χ2 = 6.905, df = 2, P = 0.546; pfubp1: χ2 = 4.883, df = 2, P = 0.769).
Conclusions: The detection of pfap2mu and pfubp1 genotypes associated with ACT delayed parasite clearance is
evidence of gradual nascent emergence of resistance in Ghana. The results will serve as baseline data for surveillance
and the selection of the genotypes with drug pressure over time. The pfap2mu S160N, pfubp1 E1528D and D1525E
must be monitored in Ghanaian isolates in ACT susceptibility studies, especially when cure rates of ACTs, particularly
AL, is less than 100%.
