HETEROGENEITY IN THE CIRCUMSPOROZOITE PROTEIN GENE OF PLASMODIUM-MALARIAE ISOLATES FROM SUB-SAHARAN AFRICA

Polymorphism of the circumsporozoite protein (CSP) of Plasmodium malar iae was characterized by comparing gene sequences of twelve held isola tes obtained in Yaounde, Cameroon, Central Africa, and one clinical is olate originating from C (o) over cap te d'Ivoire, West Africa. The le ngth of the CSP gene ranged from 1266 to 1302 bp. The size polymorphis m was due to variation in the number of tandem repeat units. All P. ma lariae isolates displayed a highly conserved 5' non-repeat region. Sev en non-synonymous and two synonymous nucleotide variations were observ ed in the 3' non-repeat region. In the deduced amino acid sequence the repetitive sequences consisted of a varying number of major (Asn Ala Ala Gly (NAAG); range between 42 and 46 units) and minor (Asn Asp Ala Gly (NDAG) or Asn Asp Gin Gly (NDEG); n = six or seven units) tetrapep tide units. None of the isolates had an identical sequence at nucleoti de level. These findings suggest that polymorphism in CSP is essential ly limited to the tandem repeat domain. (C) 1998 Elsevier Science B.V. All rights reserved.