Preclinical development of a dengue tetravalent recombinant subunit vaccine: Immunogenicity and protective efficacy in nonhuman primates
Authors: Govindarajan, Dhanasekaran; Meschino, Steven; Guan, Liming; Clements, David E.; ter Meulenc, Jan H.; Casimiro, Danilo R.; Collera, Beth-Ann G.; Bett, Andrew J.
We describe here the preclinical development of a dengue vaccine composed of recombinant subunit carboxy-truncated envelope (E) proteins (DEN-80E) for each of the four dengue serotypes. Immunogenicity and protective efficacy studies in Rhesus monkeys were conducted to evaluate monovalent and tetravalent DEN-80E vaccines formulated with ISCOMATRIX (TM) adjuvant. Three different doses and two dosing regimens (0, 1, 2 months and 0, 1, 2, and 6 months) were evaluated in these studies. We first evaluated monomeric (DEN4-80E) and dimeric (DEN4-80EZip) versions of DEN4-80E, the latter generated in an attempt to improve immunogenicity. The two antigens, evaluated at 6,20 and 100 mu g/dose formulated with ISCOMATRIX (TM) adjuvant, were equally immunogenic. A group immunized with 20 mu g DEN4-80E and Alhydrogel (TM) induced much weaker responses. When challenged with wild-type dengue type 4 virus, all animals in the 6 and 20 mu g groups and all but one in the DEN4-80EZip 100 mu g group were protected from viremia. Two out of three monkeys in the Alhydrogel (TM) group had breakthrough viremia. A similar study was conducted to evaluate tetravalent formulations at low (3, 3, 3, 6 mu g of DEN1-80E, DEN2-80E, DEN3-80E and DEN4-80E respectively), medium (10, 10, 10, 20 mu g) and high (50, 50, 50, 100 mu g) doses. All doses were comparably immunogenic and induced high titer, balanced neutralizing antibodies against all four DENV. Upon challenge with the four wild-type DENV, all animals in the low and medium dose groups were protected against viremia while two animals in the high-dose group exhibited breakthrough viremia. Our studies also indicated that a 0, 1, 2 and 6 month vaccination schedule is superior to the 0, 1, and 2 month schedule in terms of durability. Overall, the subunit vaccine was demonstrated to induce strong neutralization titers resulting in protection against viremia following challenge even 8-12 months after the last vaccine dose. (C) 2015 Elsevier Ltd. All rights reserved.
Convalescent patient-derived monoclonal antibodies targeting different epitopes of E protein confer protection against Zika virus in a neonatal mouse model
EMERGING MICROBES & INFECTIONS
Authors: Niu, Xuefeng; Zhao, Lingzhai; Qu, Linbing; Yao, Zhipeng; Zhan, Fan; Yan, Qihong; Zhang, Shengnan; Liang, Renshan; Chen, Peihai; Luo, Jia; Xu, Wei; Lv, Huibin; Liu, Xinglong; Lei, Hui; Yi, Changhua; Li, Pingchao; Wang, Qian; Wang, Yang; Yu, Lei; Zhang, Xiaoyan; Bryan, L. Aubrey; Davidson, Edgar; Doranz, J. Benjamin; Feng, Liqiang; Pan, Weiqi; Zhang, Fuchun; Chen, Ling
The Zika virus (ZIKV) outbreak and its link to microcephaly triggered a public health concern. To examine antibody response in a patient infected with ZIKV, we used single-cell PCR to clone 31 heavy and light chain-paired monoclonal antibodies (mAbs) that bind to ZIKV envelope (E) proteins isolated from memory B cells of a ZIKV-infected patient. Three mAbs (7B3, 1C11, and 6A6) that showed the most potent and broad neutralization activities against the African, Asian, and American strains were selected for further analysis. mAb 7B3 showed an IC50 value of 11.6 ng/mL against the circulating American strain GZ02. Epitope mapping revealed that mAbs 7B3 and 1C11 targeted residue K394 of the lateral ridge (LR) epitope of the EDIII domain, but 7B3 has a broader LR epitope footprint and recognizes residues T335, G337, E370, and N371 as well. mAb 6A6 recognized residues D67, K118, and K251 of the EDII domain. Interestingly, although the patient was seronegative for DENV infection, mAb 1C11, originating from the VH3-23 and VK1-5 germline pair, neutralized both ZIKV and DENV1. Administration of the mAbs 7B3, 1C11, and 6A6 protected neonatal SCID mice infected with a lethal dose of ZIKV. This study provides potential therapeutic antibody candidates and insights into the antibody response after ZIKV infection.