Pacheco Juan M, Butler John E, Jew Jessica, Ferman Geoffrey S, Zhu James, Golde William T
Plum Island Animal Disease Center, Agricultural Research Service, USDA, Greenport, NY 11944-0848, USA.
Clin Vaccine Immunol. 2010 Apr;17(4):550-8. doi: 10.1128/CVI.00429-09. Epub 2010 Jan 27.
Foot-and-mouth disease virus (FMDV) continues to be a significant economic problem worldwide. Control of the disease involves the use of killed-virus vaccines, a control measure developed decades ago. After natural infection, the primary site of replication of FMDV is the pharyngeal area, suggesting that a mucosal immune response is the most effective. Humoral immunity to killed-virus vaccination induces antibodies that can prevent the clinical disease but not local infection. Determining whether infection or vaccination stimulates IgA-mediated local immunity depends on the method of analysis. Different assays have been described to analyze the quality of antibody responses of cattle and swine to FMDV, including indirect double-antibody sandwich enzyme-linked immunosorbent assay (IDAS-ELISA) and antibody capture assay-ELISA (ACA-ELISA). We tested these assays on swine and show that vaccinated animals had FMDV-specific IgM and IgG but no IgA in either serum or saliva. After the infection, both assays detected FMDV-specific IgM, IgG, and IgA in serum. Notably, serum IgA was more readily detected using the ACA-ELISA, whereas IgA was not detected in saliva with this assay. FMDV-specific IgA antibodies were detected in saliva samples using the IDAS-ELISA. These data show that parenterally administered, killed-virus vaccine does not induce a mucosal antibody response to FMDV and illuminates limitations and appropriate applications of the two ELISAs used to measure FMDV-specific responses. Further, the presence of the IgA antivirus in serum correlates with the presence of such antibodies in saliva.
口蹄疫病毒（FMDV）仍然是全球一个重大的经济问题。该疾病的防控涉及使用灭活病毒疫苗，这是几十年前就已研发出的一种防控措施。自然感染后，FMDV的主要复制部位是咽部区域，这表明黏膜免疫反应最为有效。对灭活病毒疫苗的体液免疫可诱导产生能预防临床疾病但无法预防局部感染的抗体。确定感染或疫苗接种是否刺激了IgA介导的局部免疫取决于分析方法。已经描述了不同的检测方法来分析牛和猪对口蹄疫病毒抗体反应的质量，包括间接双抗体夹心酶联免疫吸附测定（IDAS-ELISA）和抗体捕获测定-ELISA（ACA-ELISA）。我们在猪身上测试了这些检测方法，结果显示接种疫苗的动物血清和唾液中均有FMDV特异性IgM和IgG，但无IgA。感染后，两种检测方法均在血清中检测到了FMDV特异性IgM、IgG和IgA。值得注意的是,使用ACA-ELISA更容易检测到血清中的IgA，而该检测方法在唾液中未检测到IgA。使用IDAS-ELISA在唾液样本中检测到了FMDV特异性IgA抗体。这些数据表明，经肠胃外给药的灭活病毒疫苗不会诱导对口蹄疫病毒的黏膜抗体反应，并阐明了用于测量FMDV特异性反应的两种ELISA的局限性和适当应用。此外，血清中IgA抗病毒抗体的存在与唾液中此类抗体的存在相关。
