Cécile Hamers-Casterman

Molecular cloning and sequence analysis of the gene encoding the major merozoite surface antigen of Plasmodium chabaudi chabaudi IP-PC1.

The complete nucleotide sequence of the gene encoding the precursor to the major merozoite surface antigens of Plasmodium chabaudi chabaudi strain IP-PC1 has been determined. A single open reading frame was detected, that coded for a protein of 199 kDa. The encoded protein (p199) contains putative signal and membrane anchor sequences and shows a clustering of Cys residues in the last 120 amino acids. Incompletely conserved tandem repeat oligopeptides are present at different positions in the molecule. P199 shows 69% overall homology to the analogous antigen in Plasmodium yoelii yoelii strain YM. The divergence between these antigens is largely confined to 4 areas where a number of insertions and/or deletions have occurred. All repeats occur in these divergent regions. The overall homology with both alleles of Plasmodium falciparum PMMSA is 33%.

IgM allotypes in rabbit

Six new IgM allotypes-Msl6, Msl7, Ms21, Ms23, Ms24, and Ms25-have been detected. Genetics of these markers has been studied by radioimmunoassay, since immunodiffusion in gel was not sensitive enough to detect low concentrations of IgM in the serum. All the six markers are closely linked to thea locus; Ms 16 and Ms 17 behave as alleles and can be found associated with any of the three majora locus markers. In contrast to these findings, the other four allotypes are always associated with haplotypes carrying a particular a-locus marker associated with a particular μ chain allotype (Ms 16 or Ms 17).

A second crossing-over betweend anda locus in rabbit immunoglobulin γ chain

In rabbit, mouse, and man, and probably in most animals, the structural genes of the heavy chain of immunoglobulins are inherited as a closely linked complex. The situation in the rabbit is unique because a number of allotypic markers are found which are common to all classes of heavy chains and are presumably located in the variable region. These so-called a locus markers al, a2, and a3 are found on most heavy chains of all classes and behave as alleles at the level of resolution of mammalian genetics. They are probably correlated with multiple amino acid interchanges. Other markers are only found on defined classes of heavy chains and these, when analyzed, are characterized by single amino acid differences in the constant region. In the 7 chain, the allelic dll

Allotypes of rabbit IgM linked to be b Locus of the kappa polypeptide chain

SummaryIt was possible to obtain antisera againstMs7, the allele of IgM marker Ms3. We showed that both allotypes, Ms3 and Ms7, although occurring specifically on IgM molecules, are linked to allelic variants of the b4 light chain (b4.1 and b4.2). Similar markers linked to b5, b6, or b9 have not yet been discovered.

Structure of a Plasmodium chabaudi acidic phosphoprotein that is associated with the host erythrocyte membrane

We have characterized by molecular cloning and sequencing a Plasmodium chabaudi antigen that is associated with the membrane of the infected erythrocyte throughout the entire intraerythrocytic cycle. The protein (PcEMA1) has a predicted size of 50 kDa and contains a major tandem repeat array of 16 octapeptides that constitutes almost 30% of the protein. At its amino-terminus, PcEMA1 has a string of hydrophobic residues characteristic of a secreted protein, but does not contain a hydrophobic membrane-spanning segment. The antigen appears to reside on the cytoplasmic face of the erythrocytic membrane. PcEMA1 has a predicted pI of 4.4 and is a potential phosphoprotein.

Characterization of a Plasmodium chabaudi gene encoding a protein with glutamate-rich tandem repeats

Abstract Several highly antigenic proteins containing tandem repeats rich in glutamic acid residues have been described in Plasmodium falciparum. However, relatively little information is available about analogous genes in rodent parasites. This report describes a 4.2-kb genomic DNA fragment from P. chabaudi with a deduced amino acid sequence that is predominantly glutamate-rich tandem repeats. Several different monoclonal antibodies raised against a 93-kDa P. chabaudi protein, which does not correspond to the cloned DNA fragment, recognize a recombinant protein expressed from the 4.2-kb DNA fragment. The only sequence similarities between these two genes are tandem repeats with a predominance of glutamate pairs followed by a hydrophobic residue. This repetitious-sequence motif may be the basis for the observed cross-reactivity. A similar motif has been demonstrated to be the basis for antibody cross-reactivity between glutamate-rich proteins of P. falciparum. The expression of multiple glutamate-rich proteins with cross-reacting epitopes may be a general phenomenon in Plasmodium species.