PubMed HealthSearch

Biomedical subjects

C Hamers-Casterman

Publications and source records attributed to C Hamers-Casterman.

At least 19 recordsLinked to original sources

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.

Amino Acid Sequence

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%.

Amino Acid Sequence

Phylogeny of the rabbit gamma-chain determinants: a d12-like antigenic determinant in Pronolagus rupestris.

A survey for constant region gamma-chain allotypes (de locus) was undertaken in different lagomorph genera. As yet only Pronolagus rupestris, a paleolaginae, showed the presence of a determinant similar to rabbit d12 although it lacked the widespread e15 determinant. All seven individuals possessed the d12 like determinant which was studied by immunodiffusion, haemagglutination inhibition, radiobinding and binding inhibition assays. In addition, a new enzymic method for typing for d12, based on the presence of the asymmetric rabbit hinge carbohydrate linked to the d12 characteristic threonine, is presented. This method suggests, however, that, unlike the d12 rabbit, Pronolagus does not seem to have a majority of IgG molecules with a glycosylated hinge.

Animals

Evidence for quasi-silent germline genes coding for phylogenetically ancient determinants of the rabbit a locus allotypes.

Anti-a2 sera raised in a3 rabbits are shown to detect determinants on a2 molecules which are different from those detected by anti-a2 sera raised in a1 animals. The former determinants are occasionally observed at a low level in rabbits of the a1 allotype and at a high level in sera of Leporidae of different genera. The two types of anti-a2 sera are shown to compete for the same sterical region of the a2 molecules. All homogeneous a2 molecules which have been tested show both types of determinants.

Amino Acid Sequence

Double line phenotypes in rabbit IgG allotypes and their relation to the cis/trans configuration of the IgG markers.

Rabbit antiallotype sera raised against heavy chain markers sometimes show double precipitin lines with all or some of the corresponding antigens (double and single line phenotypes). In a number of cases the double line phenotypes behave as alleles of the single line phenotypes and this feature allows a genetic and immunochemical analysis of these systems. In three cases that have been analysed, the double line phenotype arise when a precipitating a locus allotype and a non-precipitating d or e locus allotype are present on the same molecule (a1 and d14), (a1 and d11), (a3 and d11). This only happens when the corresponding genes are present on the same chromosome (cis configuration) of the diploid pair. These sera are therefore useful for determining directly the genotype of the animals.

Animals

Restriction of the anti-bovine serum albumin response in rabbits immunized with Micrococcus lysodeikticus.

Rabbits capable of producing antibodies of restricted heterogeneity in response to Micrococcus lysodeikticus are equally capable of producing antibodies of restricted heterogeneity to bovine serum albumin. These antibodies are produced when animals are simultaneously injected with micrococcus and BSA and their specificity is restricted to a small number of epitopes. These results suggest that micrococcal vaccines can induce the restriction of heterogeneity in antibodies raised against totally unrelated antigens.

Animals

Rheumatoid factor appearance in Micrococcus lysodeikticus immunization and its interference with allotype specific reactions.

Rabbits hyperimmunized with Micrococcus lysodeikticus produce, in addition to anti-cell wall antibodies, considerable amounts of anti-immunoglobulins or rheumatoid factors which can interfere with immune reactions. In particular, in immunodiffusion, they can reveal non precipitating systems for which the immunodiffusion typing sera are usually not tested. In our hands, rabbit allotypes d12 and A8 give rise to visible immunodiffusion reactions in presence of rheumatoid factors. Inhibition of this reaction can be used to type for these markers in sera which do not contain the rheumatoid factors.

Antibodies, Bacterial