Replication kinetics and cell tropism of an immunosuppressive feline leukaemia virus.
To elucidate in vivo cell tropism and infection kinetics of an immunodeficiency-inducing isolate of feline leukaemia virus (FeLV-FAIDS), we quantified the two major genotypes comprising FeLV-FAIDS [the replication-competent common form (clone 61E) and the replication-defective variant (clone 61C)] in lymphocyte and leukocyte populations from infected cats. Micromagnetic separation of cell subsets, virus genome-specific PCR and flow cytometry were used to demonstrate the following sequence of events in infected animals: (i) very early replication of both 61E and 61C in CD4 T cells (provirus burden 0.2 to 1 copy/cell at 2-4 weeks post-infection); (ii) lower magnitude replication of both viruses in CD8 T cells and B cells during this initial phase of infection; (iii) plateauing of CD4 cell virus burden accompanied by escalation in CD8 and B cell provirus burdens after 4 weeks; (iv) extensive infection of haemopoietic and circulating myeloid cells. FeLV-FAIDS 61E and 61C replication kinetics and lymphocyte tropisms were similar in blood and lymph nodes, where provirus burdens ranged from 0.15 to 1.0 copy/cell. Moreover, virus infection was productive; 8-48 percent of blood lymphocytes, 35-81 percent of node lymphocytes and 53-98 percent of bone marrow cells expressed FeLV capsid antigen (p27 Gag). These findings suggest that the immunosuppressive potency of FeLV-FAIDS reflects the unique cytopathicity rather than unique cytotropism of its 61C (versus 61E) component.
Quackenbush
S L
SL
Department of Pathology, Colorado State University, Fort Collins, CO 80523-1671, USA.
Mullins
J I
JI
Hoover
E A
EA
D000818:Animals; D000956:Antigens, Viral / Q000096:biosynthesis; D001483:Base Sequence; D015139:Blotting, Southern; D001853:Bone Marrow / Q000821:virology; D001854:Bone Marrow Cells; D002415:Cats; D004279:DNA, Viral; D004906:Erythrocyte Count; D016181:Feline Acquired Immunodeficiency Syndrome / Q000097:blood / Q000276:immunology / Q000821:virology*; D007700:Kinetics; D005256:Leukemia Virus, Feline / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D008198:Lymph Nodes / Q000821:virology; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000821:virology; D008264:Macrophages / Q000821:virology; D008969:Molecular Sequence Data; D011533:Proviruses / Q000502:physiology; D014779:Virus Replication
D000956:Antigens, Viral; D004279:DNA, Viral