title: Changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with porcine reproductive and respiratory syndrome virus and porcine circovirus type 2.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are pathogens, which can significantly affect the swine industry worldwide. Field surveys suggest that simultaneous PRRSV and PCV2 infection is common in pigs. The objective of this study was to measure the changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with PRRSV and PCV2, in order to analyze the synergistic influence of co-infection on the immune system. Changes in peripheral blood leukocyte subpopulations were systematically measured by flow cytometry (FCM). The levels of antibodies to PRRSV and PCV2 were detected by indirect Enzyme-Linked ImmunoSorbent Assay (ELISA) and the indirect fluorescent antibody test (IFA), respectively. Serum viral loads were measured using real-time PCR. The results showed that piglets co-infected with PRRSV and PCV2 exhibited slower generation and lower levels of antibodies to PRRSV and PCV2, and increased amounts and a prolonged presence of both PRRSV and PCV2 in serum, in comparison to the piglets infected with either virus alone. The major finding in our study was that the total and differential leukocyte counts, including white blood cells (WBCs), monocytes, granulocytes and lymphocytes (T, B and NK cells, as well as T-cell subpopulations), dramatically decreased early during co-infection with PRRSV and PCV2 for about two weeks, in contrast with animals singly infected with either PRRSV or PCV2. These results suggest that PRRSV and PCV2 co-infection results in a synergistic decrease in immune cells in the peripheral blood of piglets. These data contribute to the understanding of the immunosuppressive effects resulting from PRRSV and PCV2 co-infection in pigs.
authors.affiliation: Key Laboratory of Preventive Veterinary Medicine of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Haidian District, Beijing, China.
authors.forename: Kaichuang
authors.initials: K
authors.lastname: Shi
authors.forename: Huanrong
authors.initials: H
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Xinna
authors.initials: X
authors.lastname: Ge
authors.forename: Hong
authors.initials: H
authors.lastname: Jia
authors.forename: Shijun
authors.initials: S
authors.lastname: Zheng
authors.forename: Hanchun
authors.initials: H
authors.lastname: Yang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000097:blood; D018173:Circoviridae Infections / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000276:immunology*; D015897:Comorbidity; D005434:Flow Cytometry / Q000379:methods / Q000662:veterinary; D007958:Leukocyte Count / Q000662:veterinary; D007962:Leukocytes / Q000276:immunology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology / Q000276:immunology* / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D011897:Random Allocation; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000276:immunology* / Q000821:virology; D019562:Viral Load / Q000662:veterinary
chemical_list: D000914:Antibodies, Viral