Lunn D P, Soboll G, Schram B R, Quass J, McGregor M W, Drape R J, Macklin M D, McCabe D E, Swain W F, Olsen C W
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706, USA.
Vaccine. 1999 May 4;17(18):2245-58. doi: 10.1016/s0264-410x(98)00496-4.
Equine influenza virus infection remains one of the most important infectious diseases of the horse, yet current vaccines offer only limited protection. The equine immune response to natural influenza virus infection results in long-term protective immunity, and is characterized by mucosal IgA and serum IgGa and IgGb antibody responses. DNA vaccination offers a radical alternative to conventional vaccines, with the potential to generate the same protective immune responses seen following viral infection. Antigen-specific antibody isotype responses in serum and mucosal secretions were studied in ponies following particle-mediated delivery of hemagglutinin (HA)-DNA vaccination on three occasions at approximately 63-day intervals. One group of four ponies were vaccinated at skin and mucosal sites and the another group were vaccinated at skin sites only. All ponies were subjected to a challenge infection 30 days after the third vaccination. Skin and mucosal vaccination provided complete protection from clinical signs of infection, while skin vaccination provided partial protection; DNA vaccination provided partial protection from viral shedding. DNA vaccination generated only IgGa and IgGb antibody responses, which occurred with a higher frequency in the skin and mucosa vaccinated ponies. No mucosal IgA response was generated prior to challenge infection and IgA responses were only detected in those ponies which shed virus postchallenge. These results demonstrate that HA-DNA vaccination induces IgG(a) and IgG(b) antibody responses which are associated with protection in the absence of mucosal IgA responses. In addition, additional DNA vaccinations of mucosal sites increased protection and the frequency of seroconversion in ponies.
马流感病毒感染仍然是马最重要的传染病之一，但目前的疫苗仅提供有限的保护。马对自然流感病毒感染的免疫反应会产生长期的保护性免疫，其特征是黏膜IgA以及血清IgGa和IgGb抗体反应。DNA疫苗接种为传统疫苗提供了一种全新的替代方法，有可能产生与病毒感染后所见相同的保护性免疫反应。在以大约63天的间隔分三次进行颗粒介导的血凝素（HA）-DNA疫苗接种后，研究了小马血清和黏膜分泌物中抗原特异性抗体的同种型反应。一组四匹小马在皮肤和黏膜部位接种疫苗，另一组仅在皮肤部位接种疫苗。所有小马在第三次接种疫苗后30天接受攻毒感染。皮肤和黏膜接种可完全预防感染的临床症状，而皮肤接种仅提供部分保护；DNA疫苗接种可部分预防病毒脱落。DNA疫苗接种仅产生IgGa和IgGb抗体反应，在皮肤和黏膜接种疫苗的小马中出现的频率更高。在攻毒感染前未产生黏膜IgA反应，仅在攻毒后 shedding virus 的那些小马中检测到IgA反应。这些结果表明，HA-DNA疫苗接种可诱导IgG(a)和IgG(b)抗体反应，在没有黏膜IgA反应的情况下这些反应与保护作用相关。此外，对黏膜部位进行额外的DNA疫苗接种可增强小马的保护作用和血清转化频率。
