Molecular and Biochemical Parasitology, 44 (1991) 141-144
141
Elsevier MOLBIO 01448
Short C o m m u n i c a t i o n
Intra-generic conservation and limited inter-strain variation in a protective minor surface antigen of Plasmodium knowlesi merozoites A n d r e w P. Waters 1, Alan W. T h o m a s 2, Graham H. Mitchell 3 and T h o m a s F. M c C u t c h a n 1 1Malaria Section, Laboratory of Parasitic Disease, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, U.S.A; 2Department of Immunology, Walter Reed Army Medical Corps Institute of Research, Washington, DC, U.S.A. and Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, U.S.A; and 3Department of Immunology (MS3), The Medical School, Guy's Hospital, London, U.K, (Received 9 August 1990; accepted 4 September 1990)
Key words: Plasmodium knowlesi; Plasmodium fragile; Malaria; Strain variation; Vaccine
A promising family of blood stage malaria vaccine candidates is typified by the 66-kDa (PK66) protein expressed on Plasmodium knowlesi merozoites [1]. Members of this family are widely distributed throughout the genus, including a highly conserved analogue in Plasmodium falciparum, which we designate PF83 [2], which has been independently cloned (AMA-1; ref. 3). Further analogues have been characterised in Plasmodium fragile [4], Plasmodium chabaudi [5] and Plasmodium vivax (A.P. Waters, unpublished resuits). Certain structural motifs are highly conserved in every member of this family so far characterised and the overall conservation of the molecule is outstanding [ 1,4]. For example, at the Cterminus, identity ranges from 32 of 33 amino acid residues (P. knowlesi to P. fragile or P. vivax) to 28 of 31 residues (P. chabaudi to P. falciparum) in the 4 analogues reported [1,3-5]. Interest in this protein family is excited by a number Correspondence address: Andrew P. Waters, Malaria Section, Laboratory of Parasitic Disease, National Institute of Allergy and Infectious Disease, NIH, Bethesda, MD 20892, U.S.A.
Note: Nucleotide sequence data reported in this paper have been submitted to the GenBank TM data base with the accession number M37854.
Abbreviations: mAb, Monoclonal antibody; CS, circumsporo-
of properties of PK66. First, the monoclonal antibodies (mAbs) by which PK66 was originally defined and their Fab fragments inhibited reinvasion in vitro of rhesus erythrocytes by merozoites in vitro [6]. The activity of the Fab fragments in particular is especially suggestive of the recognition of an invasion-related protein. Secondly, the affinity-purified PK66 was partially effective in immunising rhesus monkeys against this severe simian malaria, and those breakthrough parasitaemias that were typed revealed no variations in PK66 that destroyed reactivity with the inhibitory mAbs [7]. These attributes of PK66 argue for a crucial function in invasion. To extend this reasoning, it is important to consider the inter-strain variation which may occur in this protein. It has been established that the P. falciparum analogue varies in a limited domain specific manner [2,3]. We report here the entire sequence of the gene expressed by the Nuri strain of P. knowlesi. The H strain of P. knowlesi [ 1] was isolated from the blood of a patient from the Malaysian bush at Burket Kertau in 1966 [8], whereas the Nuri strain had been isolated from a naturally infected macaque in Negri Sembilan in 1953 [9]. Thus, there is considerable temporal and geographical separation between the two isolations. Moreover, when the circumsporozoite
zoite. 0166-6851/91/$03.50 © 1991 Elsevier Science Publishers B.V. (Biomedical Division)
142
i ~R
Tq.C~qG~ ACCC~qT[.C CI~CCTAAC ~YCCC~q'fCT ACACZC~AGA GGCTCCTAGG GCA~A~GG GTqT~A~IC A2q~..ACA~ Tbl,Y~T~ACCAAGCG'fGE~.~TAA~ ....... START FRAGILE Ei G GGAT C A - AG G -G
~ 114 ?I'I~/.ICf'gC~AL'ICRG CGIGTT'i~'~AACCGq~L~AC .1~kq'ICACt"l~3 ~T¢~CC~3~ ~ C C FR 89 A T T A G C A
~
141
Elsevier MOLBIO 01448
Short C o m m u n i c a t i o n
Intra-generic conservation and limited inter-strain variation in a protective minor surface antigen of Plasmodium knowlesi merozoites A n d r e w P. Waters 1, Alan W. T h o m a s 2, Graham H. Mitchell 3 and T h o m a s F. M c C u t c h a n 1 1Malaria Section, Laboratory of Parasitic Disease, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, U.S.A; 2Department of Immunology, Walter Reed Army Medical Corps Institute of Research, Washington, DC, U.S.A. and Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, U.S.A; and 3Department of Immunology (MS3), The Medical School, Guy's Hospital, London, U.K, (Received 9 August 1990; accepted 4 September 1990)
Key words: Plasmodium knowlesi; Plasmodium fragile; Malaria; Strain variation; Vaccine
A promising family of blood stage malaria vaccine candidates is typified by the 66-kDa (PK66) protein expressed on Plasmodium knowlesi merozoites [1]. Members of this family are widely distributed throughout the genus, including a highly conserved analogue in Plasmodium falciparum, which we designate PF83 [2], which has been independently cloned (AMA-1; ref. 3). Further analogues have been characterised in Plasmodium fragile [4], Plasmodium chabaudi [5] and Plasmodium vivax (A.P. Waters, unpublished resuits). Certain structural motifs are highly conserved in every member of this family so far characterised and the overall conservation of the molecule is outstanding [ 1,4]. For example, at the Cterminus, identity ranges from 32 of 33 amino acid residues (P. knowlesi to P. fragile or P. vivax) to 28 of 31 residues (P. chabaudi to P. falciparum) in the 4 analogues reported [1,3-5]. Interest in this protein family is excited by a number Correspondence address: Andrew P. Waters, Malaria Section, Laboratory of Parasitic Disease, National Institute of Allergy and Infectious Disease, NIH, Bethesda, MD 20892, U.S.A.
Note: Nucleotide sequence data reported in this paper have been submitted to the GenBank TM data base with the accession number M37854.
Abbreviations: mAb, Monoclonal antibody; CS, circumsporo-
of properties of PK66. First, the monoclonal antibodies (mAbs) by which PK66 was originally defined and their Fab fragments inhibited reinvasion in vitro of rhesus erythrocytes by merozoites in vitro [6]. The activity of the Fab fragments in particular is especially suggestive of the recognition of an invasion-related protein. Secondly, the affinity-purified PK66 was partially effective in immunising rhesus monkeys against this severe simian malaria, and those breakthrough parasitaemias that were typed revealed no variations in PK66 that destroyed reactivity with the inhibitory mAbs [7]. These attributes of PK66 argue for a crucial function in invasion. To extend this reasoning, it is important to consider the inter-strain variation which may occur in this protein. It has been established that the P. falciparum analogue varies in a limited domain specific manner [2,3]. We report here the entire sequence of the gene expressed by the Nuri strain of P. knowlesi. The H strain of P. knowlesi [ 1] was isolated from the blood of a patient from the Malaysian bush at Burket Kertau in 1966 [8], whereas the Nuri strain had been isolated from a naturally infected macaque in Negri Sembilan in 1953 [9]. Thus, there is considerable temporal and geographical separation between the two isolations. Moreover, when the circumsporozoite
zoite. 0166-6851/91/$03.50 © 1991 Elsevier Science Publishers B.V. (Biomedical Division)
142
i ~R
Tq.C~qG~ ACCC~qT[.C CI~CCTAAC ~YCCC~q'fCT ACACZC~AGA GGCTCCTAGG GCA~A~GG GTqT~A~IC A2q~..ACA~ Tbl,Y~T~ACCAAGCG'fGE~.~TAA~ ....... START FRAGILE Ei G GGAT C A - AG G -G
~ 114 ?I'I~/.ICf'gC~AL'ICRG CGIGTT'i~'~AACCGq~L~AC .1~kq'ICACt"l~3 ~T¢~CC~3~ ~ C C FR 89 A T T A G C A
~
