Differential Expression and Sequence Conservation of theAnaplasma marginale msp2Gene Superfamily Outer Membrane Proteins

• DOI: 10.1128/iai.01843-05
• Publication Date: 2006-05-19T23:52:41Z
• Authors: Susan M. Noh; Kelly A. Brayton; Donald P. Knowles; Joseph T. Agnes; Michael J. Dark; Wendy C. Brown; Timothy V. Baszler; Guy H. Palmer
• Keywords: 0301 basic medicine; 570; Anaplasmosis; Antigens, Bacterial; 0303 health sciences; Erythrocytes; Transcription, Genetic; Molecular Sequence Data; 500; 3. Good health; Open Reading Frames; 03 medical and health sciences; Ticks; Microbial Immunity and Vaccines; Animals; Cattle; Amino Acid Sequence; RNA, Messenger; Conserved Sequence; Bacterial Outer Membrane Proteins

ABSTRACTBacterial pathogens in the generaAnaplasmaandEhrlichiaencode a protein superfamily, pfam01617, which includes the predominant outer membrane proteins (OMPs) of each species, major surface protein 2 (MSP2) and MSP3 ofAnaplasma marginaleandAnaplasma ovis,Anaplasma phagocytophilumMSP2 (p44),Ehrlichia chaffeensisp28-OMP,Ehrlichia canisp30, andEhrlichia ruminantiumMAP1, and has been shown to be involved in both antigenic variation within the mammalian host and differential expression between the mammalian and arthropod hosts. Recently, complete sequencing of theA. marginalegenome has identified an expanded set of genes, designatedomp1-14, encoding new members of this superfamily. Transcriptional analysis indicated that, with the exception of the three smallest open reading frames,omp2,omp3, andomp6, these superfamily genes are transcribed inA. marginale-infected erythrocytes, tick midgut and salivary glands, and the IDE8 tick cell line. OMPs 1, 4, 7 to 9, and 11 were confirmed to be expressed as proteins byA. marginalewithin infected erythrocytes, with expression being either markedly lower (OMPs 1, 4, and 7 to 9) or absent (OMP11) in infected tick cells, which reflected regulation at the transcript level. Although the pfam01617 superfamily includes the antigenically variable MSP2 and MSP3 surface proteins, analysis of theomp1-14sequences throughout a cycle of acute and persistent infection in the mammalian host and tick transmission reveals a high degree of conservation, an observation supported by sequence comparisons between the St. Maries strain and Florida strain genomes.