title: Changes of lymphocyte subpopulations in pigs infected with porcine reproductive and respiratory syndrome (PRRS) virus.
abstract: Abnormal changes of T-cell subpopulation were observed in the peripheral blood lymphocytes of pigs infected with porcine reproductive and respiratory syndrome (PRRS) virus. Pigs with naturally occurring PRRS revealed increases in CD2+ and CD8+ cells, and decreases in CD4+ cells and the ratios of CD4+/CD8+ cells. Specific-pathogen-free pigs inoculated with PRRS virus showed remarkable decreases in total lymphocytes, CD4+ and CD2+ cells on Postinoculation Day (PID) 3. The decline of CD4+ cells continued for at least 14 days, while CD2+ cells showed a tendency to increase thereafter. On the other hand,CD8+ cells slightly decreased in number on PID 3, and then increased remarkably; their number was significantly larger on PIDs 28 and 35 than on PID 0. The ratios of CD4+/CD8+ cells were significantly low between PIDs 3 and 28 as compared with PID 0. However, there were no differences in thymocyte subpopulations between infected and non-infected pigs, suggesting that the PRRS virus does not modulate intrathymic T-cell differentiation. In an experiment with peripheral blood mononuclear cell cultures, PRRS virus caused neither alteration of T-cell subpopulations nor cell proliferation, suggesting that the virus is not cytotoxic for CD4+ cells and not mitogenic for CD8+ cells.
authors.affiliation: National Institute of Animal Health, Ibaraki, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Shimizu
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: K
authors.initials: K
authors.lastname: Kawashima
authors.forename: S
authors.initials: S
authors.lastname: Ohashi
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
authors.forename: T
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002478:Cells, Cultured; D005434:Flow Cytometry; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000821:virology; D016131:Lymphocyte Subsets / Q000276:immunology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology / Q000502:physiology; D013552:Swine; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014779:Virus Replication