Cytotoxic T lymphocytes (CTL) have been implicated in immunity to Plasmodium falciparum infection and disease. We have previously described the use of peptides to define malaria-specific CTL ...epitopes. To determine whether these peptide epitopes are processed intracellularly from the whole antigen we have developed recombinant vaccinia viruses (rVV) expressing three malaria antigens: thrombospondin-related adhesive protein (TRAP), Pfs16 and the C-terminal half of liver-stage antigen (LSA)-1. Target cells infected with recombinant viruses were lysed by malaria-specific CTL from semi-immune African donors. We also tested the ability of cells infected with these recombinant vaccinia viruses to re-stimulate malaria-specific CTL in peripheral blood lymphocytes from malaria immune adults. Two other pox virus recombinants, NYVAC, an attenuated vaccinia virus, and ALVAC, a canarypox virus, both expressing malaria antigens were also evaluated for their ability to stimulate malaria-specific CTL in contrast to peptide, none of these viruses successfully re-stimulated CTL from the peripheral blood lymphocytes of semi-immune donors. The ability of human CTL from naturally exposed individuals to recognize processed antigen supports the relevance of these cells in protective immunity to malaria.
Cyclin-dependent kinases (Cdks) play a central role in the regulation of the eukaryotic cell cycle. A novel gene encoding a Cdk-like protein, Pfmrk, has been isolated from the human malaria parasite ...Plasmodium falciparum. The gene has no introns and comprises an open reading frame encoding a protein of 324 amino acids with a predicted molecular mass of 38 kDa. Database searches revealed a striking similarity to the Cdk subfamily with the highest similarity to human MO15 (Cdk7). The overall sequence of Pfmrk shares 62% similarity and 46% identity with human MO15, in comparison to the 49-58% similarity and 34-43% identity with other human Cdks. Pfmrk contains two unique inserts: one consisting of 5 amino acids just before the cyclin-binding motif and the other composed of 13 amino acids within the T-loop equivalent region. Southern blots of genomic DNA digests and chromosomal separations showed that Pfmrk is a single-copy gene conserved between several parasite strains and is located on chromosome 10. A 2500-nucleotide transcript of this gene is expressed predominantly in the sexual blood stages (gametocytes), suggesting that Pfmrk may be involved in sexual stage development.
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder causing inappropriate dietary iron absorption that affects North Europeans. HH is associated with the C282Y mutation of the ...HFE gene, and the H63D mutation to a lesser degree. Both mutations are abundant in Europe, with H63D also appearing in North Africa, the Middle East, and Asia. Emigration from Europe over the past 500 years has introduced C282Y and H63D to America, Australia, New Zealand, and South Africa in an essentially predictable fashion. The distinctive characteristics of the population genetics of HH are the confined racial distribution and high frequency in North European peoples. C282Y frequencies in North Europeans are typically between 5% and 10%, with homozygotes accounting for between 1/100 and 1/400 of these populations. The scarcity of the C282Y mutation in other populations accounts for the lack of HH in non-Europeans.
The determination of the biochemical phenotype of tooth epithelium requires specification by the dental mesenchyme. This is a general feature of epithelial--mesenchymal interaction in a number of ...different epidermal organ systems (e.g., salivary gland, mammary gland, feather, skin, and hair morphogenesis). To investigate these developmental processes, we have identified a cDNA clone representing the major group of gene products associated with enamel extracellular matrix formation. The mRNAs for mouse amelogenins, representing ≈ 90% of the total enamel proteins, have been isolated and partially characterized by specific immunoprecipitation. The poly(A)-containing RNAs were used for the synthesis and cloning of the mouse amelogenin cDNA. Recombinant plasmids containing amelogenin cDNA sequences were identified by differential hybridization, hybrid-selected translation, and blot hybridization analyses. A cloned sequence was used to identify the expression of amelogenins during tooth development. The mouse cDNA sequence hybridized to genomic mouse and human DNAs. This amelogenin cDNA probe now enables molecular investigations of a number of classical problems in developmental biology.
The mRNA for phenylalanine hydroxylase (phenylalanine 4-monooxygenase, EC 1.14.16.1) has been purified from total rat liver mRNAs, of which it constitutes less than 0.25%, to greater than 10% purity ...in a single step by specific polysome immunoprecipitation. The purified mRNA was used for synthesis and cloning of its cDNA. Recombinant colonies containing phenylalanine hydroxylase DNA sequences were identified by differential hybridization, hybrid-selected translation, and blot hybridization analysis. The rat cDNA clone was capable of hybridizing with human phenylalanine hydroxylase mRNA, which will permit the isolation of the corresponding human gene for analysis of phenylketonuria, a hereditary disorder in phenylalanine metabolism that causes permanent mental retardation in humans.
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder of iron metabolism. Iron absorption from the gut is inappropriately high, resulting in increasing iron overload. The ...hemochromatosis gene (HFE) was identified in 1996 by extensive positional cloning by many groups over a period of about 20 years. Two missense mutations were identified. Homozygosity for one of these, a substitution of a tyrosine for a conserved cysteine (C282Y), has now clearly been shown to be associated with HH in 60-100% of patients. The role of the second mutation, the substitution of an aspartic acid for a histidine (H63D), is not so clear but compound heterozygotes for both these mutations have a significant risk of developing HH. Here we review other putative mutations in the HFE gene and document a number of diallelic polymorphisms in HFE introns.
Cyclin‐dependent kinases (Cdks) play a central role in the regulation of the eukaryotic cell cycle. A novel gene encoding a Cdk‐like protein, Pfmrk, has been isolated from the human malaria parasite ...Plasmodium falciparum. The gene has no introns and comprises an open reading frame encoding a protein of 324 amino acids with a predicted molecular mass of 38 kDa. Database searches revealed a striking similarity to the Cdk subfamily with the highest similarity to human MO15 (Cdk7). The overall sequence of Pfmrk shares 62% similarity and 46% identity with human MO15, in comparison to the 49–58% similarity and 34–43% identity with other human Cdks. Pfmrk contains two unique inserts: one consisting of 5 amino acids just before the cyclin‐binding motif and the other composed of 13 amino acids within the T‐loop equivalent region. Southern blots of genomic DNA digests and chromosomal separations showed that Pfmrk is a single‐copy gene conserved between several parasite strains and is located on chromosome 10. A 2500‐nucleotide transcript of this gene is expressed predominantly in the sexual blood stages (gametocytes), suggesting that Pfmrk may be involved in sexual stage development.
Animal Virus Research Institute, Pirbright, Working, Surrey, U.K.
A comparison has been made of some of the biochemical and serological characteristics of five isolates of foot-and-mouth disease ...virus (FMDV), serotype A. Three of the viruses have been assigned to the same subtype, A 22 ; the other two belong to different subtypes, A 5 and A 24 . RNA competition hybridization and two-dimensional electrophoresis of the oligonucleotides produced by ribonuclease T 1 showed that the three A 22 viruses formed a group which could be distinguished from the A 5 and A 24 viruses. However, the three A 22 viruses showed some differences by both tests. Analysis of the virus polypeptides by polyacrylamide gel electrophoresis methods also distinguished the A 22 viruses as a group distinct from the A 5 and A 24 viruses, but small differences within the A 22 group were observed using electrofocusing techniques. Serological differences were observed between the viruses using complement fixation tests and by competition radioimmunoassay with antisera obtained from guinea pigs infected with these viruses. The greatest similarity occurred between the viruses previously subtyped as A 22 , with A 5 and A 24 being distinct from the A 22 group and from each other. The relationship of the biochemical and serological data is discussed.
Received 17 May 1979;
accepted 25 June 1979.
PDF
