Genetic diversity of the S-type small subunit ribosomal RNA gene of Plasmodium knowlesi isolates from Sabah, Malaysian Borneo and Peninsular Malaysia

To determine the genetic diversity of Plasmodium (P.) knowlesi isolates from Sabah, Malaysian Borneo and Peninsular Malaysia, targeting the S-type SSU rRNA gene and including aspects of natural selection and haplotype. Thirty-nine blood samples infected with P. knowlesi were collected in Sabah, Malaysian Borneo and Peninsular Malaysia. The S-type SSU rRNA gene was amplified using polymerase chain reaction, cloned into a vector, and sequenced. The natural selection and haplotype of the S-type SSU rRNA gene sequences were determined using DnaSP v6 and illustrated using NETWORK v10. This study's 39 S-type SSU rRNA sequences and eight sequences from the Genbank database were subjected to phylogenetic analysis using MEGA 11. Overall, the phylogenetic analysis showed no evidence of a geographical cluster of P. knowlesi isolates from different areas in Malaysia based on the S-type SSU rRNA gene sequences. The S-type SSU rRNA gene sequences were relatively conserved and with a purifying effect. Haplotype sharing of the S-type SSU rRNA gene was observed between the P. knowlesi isolates in Sabah, Malaysian Borneo, but not between Sabah, Malaysian Borneo and Peninsular Malaysia. This study suggests that the S-type SSU rRNA gene of P. knowlesi isolates in Sabah, Malaysian Borneo, and Peninsular Malaysia has fewer polymorphic sites, representing the conservation of the gene. These features make the S-type SSU rRNA gene suitable for comparative studies, such as determining the evolutionary relationships and common ancestry among P. knowlesi species.