title: Association of Anaplasma marginale strain superinfection with infection prevalence within tropical regions.
abstract: Strain superinfection occurs when a second strain infects a host already infected with and having mounted an immune response to a primary strain. The incidence of superinfection with Anaplasma marginale, a tick-borne rickettsial pathogen of domestic and wild ruminants, has been shown to be higher in tropical versus temperate regions. This has been attributed to the higher prevalence of infection, with consequent immunity against primary strains and thus greater selective pressure for superinfection with antigenically distinct strains. However an alternative explanation would be the differences in the transmitting vector, Dermacentor andersoni in the studied temperate regions and Rhipicephalus microplus in the studied tropical regions. To address this question, we examined two tropical populations sharing the same vector, R. microplus, but with significantly different infection prevalence. Using two separate markers, msp1α (one allele per genome) and msp2 (multiple alleles per genome), there were higher levels of multiple strain infections in the high infection prevalence as compared to the low prevalence population. The association of higher strain diversity with infection prevalence supports the hypothesis that high levels of infection prevalence and consequent population immunity is the predominant driver of strain superinfection.
authors: Posgrado en Ciencias Genomicas, Universidad Autónoma de la Ciudad de México, México D.F., México.
authors: Elizabeth J
authors: EJ
authors: Castañeda-Ortiz
authors: Animal Disease Research Unit, USDA-ARS, Pullman, Washington, United States of America; Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, United States of America.
authors: Massaro W
authors: MW
authors: Ueti
authors: Posgrado en Ciencias Genomicas, Universidad Autónoma de la Ciudad de México, México D.F., México.
authors: Minerva
authors: M
authors: Camacho-Nuez
authors: Universidad Autónoma de Querétaro, Campus Juriquilla, Juriquilla, México.
authors: Juan J
authors: JJ
authors: Mosqueda
authors: Animal Disease Research Unit, USDA-ARS, Pullman, Washington, United States of America.
authors: Michelle R
authors: MR
authors: Mousel
authors: Animal Disease Research Unit, USDA-ARS, Pullman, Washington, United States of America.
authors: Wendell C
authors: WC
authors: Johnson
authors: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, United States of America.
authors: Guy H
authors: GH
authors: Palmer
mesh_terms: D042322:Anaplasma marginale / Q000235:genetics / Q000502:physiology*; D000712:Anaplasmosis / Q000453:epidemiology* / Q000382:microbiology*; D000818:Animals; D000942:Antigens, Bacterial / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology*; D060005:Genotyping Techniques; D005843:Geography; D008969:Molecular Sequence Data; D015995:Prevalence; D015163:Superinfection / Q000382:microbiology*; D014329:Tropical Climate
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C449089:major surface protein 1a, Anaplasma; C103348:msp2 protein, Anaplasma marginale