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Construction of a bivalent DNA vaccine co-expressing S genes of transmissible gastroenteritis virus and porcine epidemic diarrhea virus delivered by attenuated Salmonella typhimurium
- Zhang, Yudi, Zhang, Xiaohui, Liao, Xiaodan, Huang, Xiaobo, Cao, Sanjie, Wen, Xintian, Wen, Yiping, Wu, Rui, Liu, Wumei
- Virus genes 2016 v.52 no.3 pp. 354-364
- Porcine epidemic diarrhea virus, Salmonella Typhimurium, Transmissible gastroenteritis virus, diarrhea, edible vaccines, financial economics, genes, humoral immunity, immune response, immunoglobulin G, interferon-gamma, interleukin-4, lymphocyte proliferation, neonates, neutralization, neutralizing antibodies, oral vaccination, piglets, recombinant vaccines, structural proteins, viruses
- Porcine transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV) can cause severe diarrhea in newborn piglets and led to significant economic losses. The S proteins are the main structural proteins of PEDV and TGEV capable of inducing neutralizing antibodies in vivo. In this study, a DNA vaccine SL7207 (pVAXD-PS1-TS) co-expressing S proteins of TGEV and PEDV delivered by attenuated Salmonella typhimurium was constructed and its immunogenicity in piglets was investigated. Twenty-day-old piglets were orally immunized with SL7207 (pVAXD-PS1-TS) at a dosage of 1.6 × 10¹¹ CFU per piglet and then booster immunized with 2.0 × 10¹¹ CFU after 2 weeks. Humoral immune responses, as reflected by virus neutralizing antibodies and specific IgG and sIgA, and cellular immune responses, as reflected by IFN-γ, IL-4, and lymphocyte proliferation, were evaluated. SL7207 (pVAXD-PS1-TS) simultaneously elicited immune responses against TGEV and PEDV after oral immunization. The immune levels started to increase at 2 weeks after immunization and increased to levels statistically significantly different than controls at 4 weeks post-immunization, peaking at 6 weeks and declined at 8 weeks. The humoral, mucosal, and cellular immune responses induced by SL7207 (pAXD-PS1-TS) were significantly higher than those of the PBS and SL7207 (pVAXD) (p < 0.01). In particular, the levels of IFN-γ and IL-4 were higher than those induced by the single-gene vaccine SL7207 (pVAXD-PS1) (p < 0.05). These results demonstrated that SL7207 (pVAXD-PS1-TS) possess the immunological functions of the two S proteins of TGEV and PEDV, indicating that SL7207 (pVAXD-PS1-TS) is a candidate oral vaccine for TGE and PED.