Gene-Specific Antisense Oligonucleotide Therapy Targeting AMA1: A Potential Malaria Treatment

We evaluated the effects of 2'-O-methyl (2'-OMe) antisense oligonucleotides targeting the apical membrane antigen 1 (AMA1) gene of Plasmodium berghei using In vivo and In vivo models.

This study was conducted from 2019 to 2022 in Tehran, Iran. Anti-sense gapmer oligonucleotides targeting conserved regions of the AMA1 gene were designed using Vector NTI, mfold, and sfold and synthesized with 2'-OMe modifications. P. berghei ANKA cultures were treated with various ASO concentrations, and parasitemia was assessed by Giemsa-stained smears and real-time PCR. In vivo efficacy was evaluated in BALB/c mice infected intraperitoneally with P. berghei and treated subcutaneously with ASOs or control oligonucleotides; parasitemia was monitored microscopically.

Both antisense oligonucleotides showed low cytotoxicity, with cell viability exceeding 89% at the tested concentrations. In vitro, both antisense oligonucleotides significantly reduced parasitemia compared with the sense control (P=0.01), with no significant difference between the two antisense sequences (P>0.05). Both oligonucleotides also reduced AMA1 expression, with the 183-202 oligonucleotide showing the greatest inhibitory effect. In vivo, the AMA1 183-202-treated group showed significantly lower parasitemia on day 2 post-infection (P=0.048), while lower parasitemia was observed in the antisense-treated groups on subsequent assessment days.

2'-O-methyl antisense oligonucleotides targeting AMA1 reduced parasite growth and AMA1 expression In vivo and were associated with reduced parasitemia in P. berghei-infected mice. These preliminary findings support further investigation of AMA1-directed antisense therapy as a potential gene-specific antimalarial strategy. Larger, adequately powered studies are required to confirm efficacy and evaluate ASO delivery, stability, safety, and durability of gene silencing.