Lymphoproliferative Changes Induced by Infection with a Lymphotropic Herpesvirus of Guinea Pigs

The effects of experimental infection with guinea-pig herpes-like virus (GPHLV) on hematologic and histopathologic parameters were studied in Hartley strain guinea pigs inoculated intraperitoneally with 103 or 106 50% tissue culture infectious doses of GPHLV. The total leukocyte count, the percentage of cells that were mononuclear, the number of spontaneous rosette-forming cells, and hematocrit values were determined after various intervals. Cells from spleens, cervical lymph nodes, and bone marrow of animals killed at various times were assayed for infectious virus, and tissues were prepared for histological examination. Spleen-to-body weight ratios were also determined. GPHLV infection resulted in a mild, asymptomatic, transient lymphoid hyperplasia. The infected animals experienced a relative and absolute peripheral-blood lymphocytosis lasting for seven to eight weeks. The spleens showed evidence of immune stimulation for four to six weeks. Despite the transient nature of the histological and peripheralblood changes, virus was recovered by cocultivation from the spleen, bone marrow, and lymph nodes for up to eight months (the time of the last test). Infectivity titers were highest in the B-lymphocyte subpopulation during latent infection. These findings of GPHLV persistence after a mild, acute mononucleosis-type syndrome were compared with observations during human Epstein-Barr viral infection.