title: Positive inductive effect of swine interleukin-4 on immune responses elicited by modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine.
abstract: Porcine reproductive and respiratory syndrome (PRRS) has become one of the most economically important diseases to the global pork industry. Currently, the efficacies of available commercial vaccines remain questionable: the modified live-PRRSV vaccines (MLVs) were generally effective but variable in sufficient protection, and the outcomes of inactivated-PRRSV vaccines (IVs) in the field were not very promising. In the present study, we investigated the effect of swine interleukin 4 (IL-4) on the development of virus-specific immune responses elicited by an MLV. The antibody titer against PRRSV membrane proteins in pigs elicited by MLV plus recombinant plasmid encoding IL-4 (group 3) was significantly higher than those elicited by MLV alone (group 1) and MLV plus empty plasmid (group 2) from 35 days post-inoculation (dpi). Similarly, the neutralizing efficacy of sera from group 3 was markedly enhanced compared with group 1 and group 2. In cellular immunity, the ratio of CD3⁺CD4⁺/CD3⁺CD8⁺ T lymphocyte subpopulations from group 3 monitored by flow cytometry (FCM) was significantly higher than those from group 1 and group 2 from 42 dpi to 21 days post-challenge (dpc). After viral challenge, pigs in group 3 showed significantly lower virus loads in peripheral blood measured by a real-time quantitative PCR (RT-qPCR), as compared with those in group 1 and group 2. Pigs in group 1 and group 2 had a low fever and displayed mild inappetence, lethargy, rough hair coats, and no lung lesions, while those in group 3 showed almost no clinical signs, no lung lesions. The scores of clinical signs of pigs in group 3 were significantly lower than those in both group 1 and group 2. Interestingly, the scores of lung lesions showed no significant differences among the three groups. Our results indicate that swine IL-4 markedly enhanced the protective immune response of pigs and improved the efficacy of the MLV in preventing PRRS disease.
authors: 1 College of Veterinary Medicine, Shandong Agricultural University , Taian, China .
authors: Jun
authors: J
authors: Peng
authors: Jinbao
authors: J
authors: Wang
authors: Jiaqiang
authors: J
authors: Wu
authors: Yijun
authors: Y
authors: Du
authors: Jun
authors: J
authors: Li
authors: Zhongkun
authors: Z
authors: Guo
authors: Jiang
authors: J
authors: Yu
authors: Shaojian
authors: S
authors: Xu
authors: Yuyu
authors: Y
authors: Zhang
authors: Wenbo
authors: W
authors: Sun
authors: Xiaoyan
authors: X
authors: Cong
authors: Jianli
authors: J
authors: Shi
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000235:genetics / Q000494:pharmacology*; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005434:Flow Cytometry; D015847:Interleukin-4 / Q000008:administration & dosage* / Q000235:genetics / Q000494:pharmacology*; D010957:Plasmids / Q000008:administration & dosage; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000517:prevention & control / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D012720:Severity of Illness Index; D013552:Swine; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D014766:Viremia / Q000517:prevention & control
chemical_list: D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D015847:Interleukin-4