Analysis of FeLV-FAIDS provirus burden and productive infection in lymphocyte subsets in vivo

• Published in: Virology (New York, N.Y.) Vol. 223; no. 1; pp. 1 - 9
• Main Authors: Quackenbush, S.L, Dean, G.A, Mullins, J.I, Hoover, E.A
• Format: Journal Article
• Language: English
• Published: United States 01.09.1996
• Subjects: AIDS/HIV; animal diseases; animal health; Animals; B-Lymphocyte Subsets - immunology; B-Lymphocyte Subsets - virology; Cats; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - virology; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - virology; Cell Line; DNA, Viral - analysis; Feline Acquired Immunodeficiency Syndrome - blood; Feline Acquired Immunodeficiency Syndrome - virology; Gene Products, gag - immunology; Leukemia Virus, Feline - genetics; Leukemia Virus, Feline - immunology; Leukemia Virus, Feline - isolation & purification; Proviruses - isolation & purification; T-Lymphocyte Subsets - virology; viral diseases of animals and humans
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1996.0449

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 greater than or equal to 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.