Selection for antigenic diversity of Tams1, the major merozoite antigen of Theileria annulata.
Tams1, the major merozoite/piroplasm surface antigen of Theileria annulata has the potential to be a component of a diagnostic ELISA test and be included in a recombinant subunit vaccine. However, the observation that this antigen displays diversity could constrain these applications. In this paper we have extensively characterized Tams1 diversity at the DNA level, using a PCR/sequencing strategy. Up to 44 alleles have been cloned and sequenced. The comparison of these alleles has identified regions of sequence conservation, variability and hyper-variability. Computer analysis of these alleles has indicated that positive selection may operate on certain regions of Tams1. Expression and Western blot analysis of selected alleles has indicated that sequence diversity is reflected in altered antigenicity and a continuum of relatedness and antibody cross recognition may exist. The possible function of the sequence conservation and polymorphism within Tams1 is discussed in relation to protein structure, host cell invasion and immune evasion.
Department of Veterinary Parasitology, University of Glasgow, Scotland, UK. fk4h@udcf.gla.ac.uk
F
F
Katzer
S
S
McKellar
L
L
Ben Miled
C
C
D'Oliveira
B
B
Shiels
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000940:Antigenic Variation; D000953:Antigens, Protozoan / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003429:Cross Reactions; D016054:DNA, Protozoan / Q000737:chemistry; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016796:Theileria annulata / Q000235:genetics / Q000276:immunology*; D014416:Tunisia
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D011993:Recombinant Fusion Proteins; C113538:Tams1 antigen