title: Association of GP51 expression and persistent CD5+ B-lymphocyte expansion with lymphomagenesis in bovine leukemia virus infected sheep.
abstract: Alterations in the circulating CD5+ B-lymphocyte population, in vitro GP51 expression, and in vivo tax/rex expression that may precede lymphomagenesis were characterized prospectively in ten experimentally BLV-infected sheep. Infection with pathogenetic BLV resulted in a significant expansion of the circulating CD5+ B-lymphocyte population in six infected sheep. Of the remaining four infected sheep that did not have persistently elevated CD5+ B-lymphocyte counts, three developed lymphoid neoplasia within 14 months post-inoculation. Neoplastic cells from two of these three sheep were CD5- B-lymphocytes, while cells from the third were CD5+ B-lymphocytes. In vitro GP51 expression was a consistent feature of circulating lymphocytes from all three sheep developing tumors, but high level tax/rex gene transcription was not detected in circulating lymphocytes prior to lymphomagenesis. Neither in vitro GP51 expression nor high level tax/rex gene transcription was associated with expansion of the CD5+ B-lymphocyte population in sheep with significantly elevated CD5+ B-lymphocyte counts. These observations indicate that BLV infection in sheep results in expansion of the circulating CD5+ B-lymphocyte population, and that this expansion is not required for the subsequent development of BLV-associated lymphoid neoplasia.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164-7040.
authors.forename: T A
authors.initials: TA
authors.lastname: Birkebak
authors.forename: G H
authors.initials: GH
authors.lastname: Palmer
authors.forename: W C
authors.initials: WC
authors.lastname: Davis
authors.forename: D P
authors.initials: DP
authors.lastname: Knowles
authors.forename: T F
authors.initials: TF
authors.lastname: McElwain
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D016175:B-Lymphocyte Subsets / Q000382:microbiology*; D018956:CD5 Antigens; D004273:DNA, Neoplasm / Q000378:metabolism; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D015967:Gene Expression Regulation, Viral; D016355:Genes, pX; D001909:Leukemia Virus, Bovine / Q000235:genetics / Q000472:pathogenicity*; D008223:Lymphoma / Q000382:microbiology*; D008297:Male; D011533:Proviruses / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012756:Sheep; D014759:Viral Envelope Proteins / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D018956:CD5 Antigens; D004273:DNA, Neoplasm; D004279:DNA, Viral; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D012367:RNA, Viral; D014759:Viral Envelope Proteins