title: Ehrlichia ruminantium major antigenic protein gene (map1) variants are not geographically constrained and show no evidence of having evolved under positive selection pressure.
abstract: In a search for tools to distinguish antigenic variants of Ehrlichia ruminantium, we sequenced the major antigenic protein genes (map1 genes) of 21 different isolates and found that the sequence polymorphisms were too great to permit the design of probes which could be used as markers for immunogenicity. Phylogenetic comparison of the 21 deduced MAP1 sequences plus another 9 sequences which had been previously published did not reveal any geographic clustering among the isolates. Maximum likelihood analysis of codon and amino acid changes over the phylogeny provided no statistical evidence that the gene is under positive selection pressure, suggesting that it may not be important for the evasion of host immune responses.
authors.affiliation: Onderstepoort Veterinary Institute, Onderstepoort 0110, South Africa. maria@ovisun.ovi.ac.za
authors.forename: M T
authors.initials: MT
authors.lastname: Allsopp
authors.forename: C M
authors.initials: CM
authors.lastname: Dorfling
authors.forename: J C
authors.initials: JC
authors.lastname: Maillard
authors.forename: A
authors.initials: A
authors.lastname: Bensaid
authors.forename: D T
authors.initials: DT
authors.lastname: Haydon
authors.forename: H
authors.initials: H
authors.lastname: van Heerden
authors.forename: B A
authors.initials: BA
authors.lastname: Allsopp
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000940:Antigenic Variation; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D004536:Ehrlichia / Q000235:genetics* / Q000276:immunology; D019143:Evolution, Molecular; D006357:Heartwater Disease / Q000453:epidemiology / Q000382:microbiology; D016013:Likelihood Functions; D008969:Molecular Sequence Data; D010802:Phylogeny; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C086402:major antigenic protein 1, Cowdria ruminantium