Analysis of FeLV-FAIDS provirus burden and productive infection in lymphocyte subsets in vivo.
To help elucidate the immunopathogenesis of feline leukemia virus (FeLV)-induced immunodeficiency we studied the tropism of viruses derived from the FeLV-FAIDS isolate for lymphocyte subpopulations in cats. FeLV-FAIDS is composed of a replication-competent virus typical of subgroup A FeLV (prototype, clone 61E) and a family of replication-defective but immunopathogenic variant viruses (prototype, clone 61C). We sorted CD4+, CD8+, and IgG+ lymphocytes to > or = 97% purity and analyzed viral load in each cell population via genome-specific semiquantitative PCR. Both the 61E and 61C viruses were tropic for CD4+ and CD8+ T cells as well as IgG+ B lymphocytes in blood and lymph node. High provirus burden were established for both virus genomes-ranging from 0.3 to > 2 copies/cell. To identify the fraction of circulating cells which expressed viral antigen in vivo, we developed a flow cytometric method to simultaneously label blood leukocytes for surface immunophenotype and intracytoplasmic FeLV CA (p27 Gag). These experiments established that 20 to 60% of CD4+, CD8+, and IgG+ lymphocytes and > 85% of monocytes and granulocytes expressed FeLV p27 intracellularly. Thus the in vivo target cells for FeLV-FAIDS infection are manifold and include CD4+ and CD8+ T cells, B cells, and myeloid cells.
Quackenbush
S L
SL
Department of Pathology, Colorado State University, Fort Collins 80523, USA.
Dean
G A
GA
Mullins
J I
JI
Hoover
E A
EA
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000821:virology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D002415:Cats; D002460:Cell Line; D004279:DNA, Viral / Q000032:analysis; D016181:Feline Acquired Immunodeficiency Syndrome / Q000097:blood / Q000821:virology*; D015683:Gene Products, gag / Q000276:immunology; D005256:Leukemia Virus, Feline / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D011533:Proviruses / Q000302:isolation & purification; D016176:T-Lymphocyte Subsets / Q000821:virology*
D004279:DNA, Viral; D015683:Gene Products, gag