title: Apparent elimination of EIAV ancestral species in a long-term inapparent carrier.
abstract: Equine infectious anemia virus (EIAV) envelope variation produces newly dominant quasispecies with each sequential disease cycle; new populations arise, and previous plasma quasispecies, including the original inoculum, become undetectable. The question remains whether these ancestral variants exist in tissue reservoirs or if the immune system eliminates quasispecies from persistent infections. To examine this, an EIAV long-term inapparent carrier was immune suppressed with dexamethasone. Immune suppression resulted in increased plasma viral loads by approximately 10(4) fold. Characterization of pre- and post-immune suppression populations demonstrated continual envelope evolution and revealed novel quasispecies distinct from defined populations from previous disease stages. Analysis of the tissue and plasma populations post-immune suppression indicated the original infectious inoculum and early populations were undetectable. Therefore, the host immune system apparently eliminated a diverse array of antigenic variants, but viral persistence was maintained by relentless evolution of new envelope populations from tissue reservoirs in response to ongoing immune pressures.
authors.affiliation: Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
authors.forename: Jodi K
authors.initials: JK
authors.lastname: Craigo
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Sturgeon
authors.forename: Sheila J
authors.initials: SJ
authors.lastname: Cook
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Issel
authors.forename: Caroline
authors.initials: C
authors.lastname: Leroux
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Montelaro
mesh_terms: D000818:Animals; D002353:Carrier State / Q000276:immunology / Q000662:veterinary* / Q000821:virology*; D004859:Equine Infectious Anemia / Q000276:immunology / Q000821:virology*; D019143:Evolution, Molecular; D014644:Genetic Variation; D006736:Horses / Q000276:immunology / Q000821:virology*; D004860:Infectious Anemia Virus, Equine / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D008198:Lymph Nodes / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D010949:Plasma / Q000821:virology; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D013997:Time Factors; D019562:Viral Load
chemical_list: D012367:RNA, Viral