Characterization of porcine circovirus type 2 (PCV2) infection in swine lymphocytes using mitogen-stimulated peripheral blood lymphocytes from healthy PCV2-carrier pigs.
Information regarding the susceptibility of swine lymphocytes to PCV2 is rather limited. To further explore and characterize the PCV2 infection in swine lymphocytes, an in vitro model using concanavalin A (Con A)-stimulated peripheral blood lymphocytes (PBLs) obtained from clinically healthy PCV2-carrier pigs was introduced. It was found that the PCV2 antigen-containing rate was below 2% in PBLs from healthy PCV2-free pigs following treated simultaneously with Con A and PCV2. However, significantly higher PCV2 antigen- and nucleic acid-containing rates could be seen in Con A-stimulated PBLs from clinically healthy PCV2-carrier pigs. Prior to Con A treatment, both of the PCV2 antigen- and nucleic acid-containing rates in PBLs from healthy PCV2-carrier pigs were less than 1%; however, they reached 22.1+/-5.7% by flow cytometry and 27.1+/-6.5% by in situ hybridization, respectively, at 4-day post-incubation with Con A. Phenotyping of PCV2 antigen-containing cells revealed that PCV2-positive cells could be detected in both T and B lymphocyte populations within which IgM-positive B lymphocytes appeared to have a relatively higher positive rate. The Con A-stimulated PBLs also displayed a significantly higher viral load by the measurement of either PCV2 DNA copy number or viral titer when compared with the non-treated PBLs from healthy PCV2-carrier pigs. The results indicate that PBLs, especially IgM-bearing B lymphocytes, are indeed susceptible to PCV2 infection and PCV2 is capable of replicating in dividing lymphocytes. This activation-induced replication may explain in part the pathogenesis of lymphoid depletion in PMWS-affected pigs.
Division of Pathobiology, Graduate Institute of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan, ROC.
Chun-Ming
CM
Lin
Chian-Ren
CR
Jeng
Hui-Wen
HW
Chang
Ing-Cherng
IC
Guo
Yu-Liang
YL
Huang
Yi-Chieh
YC
Tsai
Mi-Yuan
MY
Chia
Victor Fei
VF
Pang
D000818:Animals; D000956:Antigens, Viral / Q000097:blood / Q000276:immunology; D002353:Carrier State / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D018173:Circoviridae Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000254:growth & development* / Q000276:immunology; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D016130:Immunophenotyping; D017403:In Situ Hybridization / Q000662:veterinary; D008214:Lymphocytes / Q000276:immunology* / Q000821:virology*; D008297:Male; D008856:Microscopy, Fluorescence / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D053570:Porcine Postweaning Multisystemic Wasting Syndrome / Q000276:immunology* / Q000821:virology; D013552:Swine
D000956:Antigens, Viral; D004279:DNA, Viral