Azevedo Marli S P, Yuan Lijuan, Iosef Cristiana, Chang Kyeong-Ok, Kim Yunjeong, Nguyen Trang Van, Saif Linda J
Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio 44691.
Clin Diagn Lab Immunol. 2004 Jan;11(1):12-20. doi: 10.1128/cdli.11.1.12-20.2004.
A sequential mucosal prime-boost vaccine regimen of oral attenuated (Att) human rotavirus (HRV) priming followed by intranasal (i.n.) boosting with rotavirus protein VP2 and VP6 rotavirus-like particles (2/6-VLPs) has previously been shown to be effective for induction of intestinal antibody-secreting cell (ASC) responses and protection in gnotobiotic pigs. Because serum or fecal antibody titers, but not intestinal ASC responses, can be used as potential markers of protective immunity in clinical vaccine trials, we determined the serum and intestinal antibody responses to this prime-boost rotavirus vaccine regimen and the correlations with protection. Gnotobiotic pigs were vaccinated with one of the two sequential vaccines: AttHRV orally preceding 2/6-VLP (VLP2x) vaccination (AttHRV/VLP2x) or following VLP2x vaccination (VLP2x/AttHRV) given i.n. with a mutant Escherichia coli heat-labile toxin (mLT) as adjuvant. These vaccines were also compared with three i.n. doses of VLP+mLT (VLP3x) and one and three oral doses of AttHRV (AttHRV1x and AttHRV3x, respectively). Before challenge all pigs in the AttHRV/VLP2x group seroconverted to positivity for serum immunoglobulin A (IgA) antibodies. The pigs in this group also had significantly higher (P < 0.05) intestinal IgA antibody titers pre- and postchallenge and IgG antibody titers postchallenge compared to those in the other groups. Statistical analyses of the correlations between serum IgM, IgA, IgG, and virus-neutralizing antibody titers and protection demonstrated that each of these was an indicator of protective immunity induced by the AttHRV3x and the AttHRV/VLP2x regimens. However, only IgA and not IgM or IgG antibody titers in serum were highly correlated (R2 = 0.89; P < 0.001) with the corresponding isotype antibody (IgA) titers in the intestines among all the vaccinated groups, indicating that the IgA antibody titer is probably the most reliable indicator of protection.
先前已证明，一种序贯黏膜初免-加强疫苗方案有效，该方案为先口服减毒（Att）人轮状病毒（HRV）进行初免，随后鼻内（i.n.）给予轮状病毒蛋白VP2和VP6轮状病毒样颗粒（2/6-VLPs）进行加强免疫，可在无菌猪中诱导肠道抗体分泌细胞（ASC）反应并提供保护。由于在临床疫苗试验中，血清或粪便抗体滴度而非肠道ASC反应可作为保护性免疫的潜在标志物，因此我们测定了对这种初免-加强轮状病毒疫苗方案的血清和肠道抗体反应以及与保护作用的相关性。无菌猪接种两种序贯疫苗之一：口服AttHRV后进行鼻内2/6-VLP（VLP2x）接种（AttHRV/VLP2x），或鼻内接种VLP2x后口服AttHRV（VLP2x/AttHRV），并使用突变型大肠杆菌不耐热毒素（mLT）作为佐剂。还将这些疫苗与鼻内接种的三剂VLP+mLT（VLP3x）以及口服一剂和三剂AttHRV（分别为AttHRV1x和AttHRV3x）进行了比较。在攻毒前，AttHRV/VLP2x组的所有猪血清转化为血清免疫球蛋白A（IgA）抗体阳性。与其他组相比，该组猪在攻毒前后的肠道IgA抗体滴度以及攻毒后的IgG抗体滴度也显著更高（P<0.05）。对血清IgM、IgA、IgG和病毒中和抗体滴度与保护作用之间的相关性进行统计分析表明，这些指标均是AttHRV3x和AttHRV/VLP2x方案诱导的保护性免疫的指标。然而，在所有接种组中，血清中只有IgA抗体滴度与肠道中相应的同型抗体（IgA）滴度高度相关（R2 = 0.89；P<0.001），而IgM或IgG抗体滴度则不然，这表明IgA抗体滴度可能是最可靠的保护指标。
