Genetic diversity of the full length apical membrane antigen-1 of Plasmodium knowlesi clinical isolates from Peninsular Malaysia

• Main Authors: Ng, Y. L., Fong, Mun Yik, Lau, Yee Ling
• Format: Article
• Published: Malaysian Soc Parasitology Tropical Medicine 2021
• Subjects: R Medicine (General)
• Online Access: http://eprints.um.edu.my/27090/
• Institution: Universiti Malaya

The Plasmodium knowlesi apical membrane antigen-1 (PkAMA-1) plays an important role in the invasion of the parasite into its host erythrocyte, and it has been regarded as a potential vaccine candidate against human knowlesi malaria. This study investigates genetic diversity and natural selection of the full length PkAMA-1 of P. knowlesi clinical isolates from Peninsular Malaysia. Blood samples were collected from P. knowlesi malaria patients from Peninsular Malaysia. The PkAMA-1 gene was amplified from DNA samples using PCR, cloned into a plasmid vector and sequenced. Results showed that nucleotide diversity of the full length PkAMA-1 from Peninsular Malaysia isolates (it: 0.006) was almost similar to that of Sarawak (pi: 0.005) and Sabah (pi: 0.004) isolates reported in other studies. Deeper analysis revealed Domain I (pi: 0.007) in the PkAMA-1 had the highest diversity as compared to Domain II (pi: 0.004) and Domain III (pi: 0.003). Z-test indicated negative (purifying) selection of the gene. Combined alignment analysis at the amino acid level for the Peninsular Malaysia and Sarawak PkAMA-1 sequences revealed 34 polymorphic sites. Thirty-one of these sites were dimorphic, and 3 were trimorphic. The amino acid sequences could be categorised into 31 haplotypes. In the haplotype network, PkAMA-1 from Peninsular Malaysia and Sarawak were separated into two groups.