Ruan Xiaosai, Liu Mei, Casey Thomas A, Zhang Weiping
Vaccinology/Veterinary & Biomedical Sciences Department/The Center for Infectious Disease Research, Box 2157, South Dakota State University, Brookings, SD 57006, USA.
Clin Vaccine Immunol. 2011 Oct;18(10):1593-9. doi: 10.1128/CVI.05120-11. Epub 2011 Aug 3.
Enterotoxigenic Escherichia coli (ETEC) strains expressing K88 (F4) or F18 fimbriae and heat-labile (LT) and/or heat-stable (ST) toxins are the major cause of diarrhea in young pigs. Effective vaccines inducing antiadhesin (anti-K88 and anti-F18) and antitoxin (anti-LT and anti-ST) immunity would provide broad protection to young pigs against ETEC. In this study, we genetically fused nucleotides coding for peptides from K88ac major subunit FaeG, F18 minor subunit FedF, and LT toxoid (LT(192)) A2 and B subunits for a tripartite adhesin-adhesin-toxoid fusion (FaeG-FedF-LT(192)A2:B). This fusion was used for immunizations in mice and pigs to assess the induction of antiadhesin and antitoxin antibodies. In addition, protection by the elicited antiadhesin and antitoxin antibodies against a porcine ETEC strain was evaluated in a gnotobiotic piglet challenge model. The data showed that this FaeG-FedF-LT(192)A2:B fusion elicited anti-K88, anti-F18, and anti-LT antibodies in immunized mice and pigs. In addition, the anti-porcine antibodies elicited neutralized cholera toxin and inhibited adherence against both K88 and F18 fimbriae. Moreover, immunized piglets were protected when challenged with ETEC strain 30302 (K88ac/LT/STb) and did not develop clinical disease. In contrast, all control nonvaccinated piglets developed severe diarrhea and dehydration after being challenged with the same ETEC strain. This study clearly demonstrated that this FaeG-FedF-LT(192)A2:B fusion antigen elicited antibodies that neutralized LT toxin and inhibited the adherence of K88 and F18 fimbrial E. coli strains and that this fusion could serve as an antigen for vaccines against porcine ETEC diarrhea. In addition, the adhesin-toxoid fusion approach used in this study may provide important information for developing effective vaccines against human ETEC diarrhea.
表达K88（F4）或F18菌毛以及不耐热（LT）和/或耐热（ST）毒素的产肠毒素大肠杆菌（ETEC）菌株是仔猪腹泻的主要原因。诱导抗粘附素（抗K88和抗F18）和抗毒素（抗LT和抗ST）免疫的有效疫苗将为仔猪提供针对ETEC的广泛保护。在本研究中，我们将编码K88ac主要亚基FaeG、F18次要亚基FedF以及LT类毒素（LT(192)）A2和B亚基的肽的核苷酸进行基因融合，构建了一种三方粘附素-粘附素-类毒素融合物（FaeG-FedF-LT(192)A2:B）。该融合物用于在小鼠和猪中进行免疫，以评估抗粘附素和抗毒素抗体的诱导情况。此外，在无菌仔猪攻毒模型中评估了所诱导的抗粘附素和抗毒素抗体对猪ETEC菌株的保护作用。数据表明，这种FaeG-FedF-LT(192)A2:B融合物在免疫小鼠和猪中诱导产生了抗K88、抗F18和抗LT抗体。此外，所诱导的抗猪抗体中和了霍乱毒素并抑制了对K88和F18菌毛的粘附。而且，用ETEC菌株30302（K88ac/LT/STb）攻毒时，免疫仔猪受到了保护，未出现临床疾病。相比之下，所有对照未接种疫苗的仔猪在受到相同ETEC菌株攻毒后都出现了严重腹泻和脱水。本研究清楚地表明，这种FaeG-FedF-LT(192)A2:B融合抗原诱导产生了中和LT毒素并抑制K88和F18菌毛大肠杆菌菌株粘附的抗体，并且这种融合物可作为抗猪ETEC腹泻疫苗的抗原。此外，本研究中使用的粘附素-类毒素融合方法可能为开发针对人类ETEC腹泻的有效疫苗提供重要信息。
