Genetic diversity of circumsporozoite protein in Plasmodium knowlesi isolates from Malaysian Borneo and Peninsular Malaysia

Abstract

Background Understanding the genetic diversity of candidate genes for malaria vaccines such as circumsporozoite protein (csp) may enhance the development of vaccines for treating Plasmodium knowlesi. Hence, the aim of this study is to investigate the genetic diversity of non-repeat regions of csp in P. knowlesi from Malaysian Borneo and Peninsular Malaysia. Methods A total of 46 csp genes were subjected to polymerase chain reaction amplification. The genes were obtained from P. knowlesi isolates collected from different divisions of Sabah, Malaysian Borneo, and Peninsular Malaysia. The targeted gene fragments were cloned into a commercial vector and sequenced, and a phylogenetic tree was constructed while incorporating 168 csp sequences retrieved from the GenBank database. The genetic diversity and natural evolution of the csp sequences were analysed using MEGA6 and DnaSP ver. 5.10.01. A genealogical network of the csp haplotypes was generated using NETWORK ver. 4.6.1.3. Results The phylogenetic analysis revealed indistinguishable clusters of P. knowlesi isolates across different geographic regions, including Malaysian Borneo and Peninsular Malaysia. Nucleotide analysis showed that the csp non-repeat regions of zoonotic P. knowlesi isolates obtained in this study underwent purifying selection with population expansion, which was supported by extensive haplotype sharing observed between humans and macaques. Novel variations were observed in the C-terminal non-repeat region of csp. Conclusions The csp non-repeat regions are relatively conserved and there is no distinct cluster of P. knowlesi isolates from Malaysian Borneo and Peninsular Malaysia. Distinctive variation data obtained in the C-terminal non-repeat region of csp could be beneficial for the design and development of vaccines to treat P. knowlesi.

Plasmodium knowlesi: the game changer for malaria eradication

“…Malaysia, Sarawak H 43 Purifying selection 2 distinct geographical clusters between Pen. Malaysia and Malaysian Borneo Chong et al (2020) [ 155 ] csp Sporozoite development and hepatocyte invasion Pen. Malaysia, Sarawak, Sabah, Singapore H 212 Purifying selection – Ng et al (2021) [ 156 ] ama1 Erythrocyte invasion Pen.…”

The Kishony Mega-Plate Experiment, a Markov Process

“…The Numerical Calculation of the Jukes-Cantor single-site Stationary and Non-stationary Models FORTRAN computer programs were written to compute the values for equations (11)(12)(13)(14) stationary model and equations (15-18) non-stationary model for two mutation rates, 1E-5 and 1E-9. The FORTRAN source code is supplied in the supplemental documentation as well as the data derived from these programs.…”

“…The Jukes-Cantor and derivative models are commonly used in an attempt to compute the evolutionary distance between different sequences of homologous genetic code. Some recent examples of applications of the Jukes-Cantor and derivative models can be found in the following references, [11][12][13][14][15]. The main difference between the Jukes-Cantor model and the derivative models listed above is derivative models allow for different mutation rates for the different elements of the transition matrix, for example, to address the fact that base transversions can have a different mutation rate than for base transitions.…”

Is there evidence of sustained human-mosquito-human transmission of the zoonotic malaria Plasmodium knowlesi? A systematic literature review

“…By contrast, genetic and mathematical modelling studies present a more nuanced picture. Genetic studies have identified genetically distinct P. knowlesi subpopulations associated with different macaque species and geographical regions, with limited but unclear evidence of host-specific circulation, which would be expected if non-zoonotic transmission were occurring [ 65 , 79 , 81 – 84 , 87 – 89 , 95 ]. A lack of evidence for drug resistance in P. knowlesi populations suggests that transmission between humans is unlikely [ 90 ], although drug resistance can take some time to develop.…”