Anaplasma marginale major surface protein 3 is encoded by a polymorphic, multigene family.
The immunodominant surface protein, MSP3, is structurally and antigenically polymorphic among strains of Anaplasma marginale. In this study we show that a polymorphic multigene family is at least partially responsible for the variation seen in MSP3. The A. marginale msp3 gene msp3-12 was cloned and expressed in Escherichia coli. With msp3-12 as a probe, multiple, partially homologous gene copies were identified in the genomes of three A. marginale strains. These copies were widely distributed throughout the chromosome. Sequence analysis of three unique msp3 genes, msp3-12, msp3-11, and msp3-19, revealed both conserved and variant regions within the open reading frames. Importantly, msp3 contains amino acid blocks related to another polymorphic multigene family product, MSP2. These data, in conjunction with data presented in previous studies, suggest that multigene families are used to vary important antigenic surface proteins of A. marginale. These findings may provide a basis for studying antigenic variation of the organism in persistently infected carrier cattle.
Alleman
A R
AR
Department of Physiological Sciences, University of Florida, Gainesville 32610, USA. ARALL@GNV.IFAS.UFL.EDU
Palmer
G H
GH
McGuire
T C
TC
McElwain
T F
TF
Perryman
L E
LE
Barbet
A F
AF
D000595:Amino Acid Sequence; D000709:Anaplasma / Q000235:genetics*; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D017124:Conserved Sequence; D018628:Gene Dosage; D005798:Genes, Bacterial; D018740:Genetic Heterogeneity; D008969:Molecular Sequence Data; D005810:Multigene Family; D011110:Polymorphism, Genetic; D011994:Recombinant Proteins; D015183:Restriction Mapping
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D011994:Recombinant Proteins; C103346:major surface protein 3, Anaplasma marginale