Demonstration of retroviral proteins associated with erythroid progenitors of cats with feline leukemia virus-induced erythroid aplasia

Feline erythroid aplasia is a fatal retrovirus-induced disease related to infection with feline leukemia virus of subgroup C. When bone marrow cells from cats inoculated with FeLV were incubated with polyvalent antibody to FeLV and cultured for erythroid colony formation, a complement-dependent inhibition of erythroid progenitors was demonstrated with virtually complete suppression of erythroid colony-forming units (CFU-E) and burst-forming units (BFU-E) evident from post-inoculation week 4 until termination in cats with progressive infection. When bone marrow cells from cats with regressive infection were treated similarly, CFU-E were inhibited on post-inoculation week 4 (98% inhibition) when the cats were viremic, and on week 6 (77% inhibition) when the leukocytes were negative for FeLV by immunofluorescence. These data suggest that the retroviral proteins are associated with erythroid progenitors or critical accessory cells and may play a role in selective suppression of erythropoiesis.