Zika Virus-Like Particles Bearing a Covalent Dimer of Envelope Protein Protect Mice from Lethal Challenge

Abstract

Zika virus (ZIKV) envelope (E) protein is the major target of neutralizing antibodies in infected host, and thus represents a candidate of interest for vaccine design. However, a major concern in the development of vaccines against ZIKV and the related dengue virus is the induction of cross-reactive poorly neutralizing antibodies that can cause antibody-dependent enhancement (ADE) of infection. This risk necessitates particular care in vaccine design. Specifically, the engineered immunogens should have their cross-reactive epitopes masked, and they should be optimized for eliciting virus-specific strongly neutralizing antibodies upon vaccination. Here, we developed ZIKV subunit- and virus-like particle (VLP)-based vaccines displaying E in its wild type form, or E locked in a covalently linked dimeric (cvD) conformation to enhance the exposure of E dimers to the immune system. Compared with their wild-type derivatives, cvD immunogens elicited antibody with higher capacity of neutralizing virus infection of cultured cells. More importantly, these immunogens protected animals from lethal challenge with both the African and Asian lineages of ZIKV, impairing virus dissemination to brain and sexual organs. Moreover, the locked conformation of E reduced the exposure of epitopes recognized by cross-reactive antibodies and therefore showed a lower potential to induce ADE in vitro. Our data demonstrated a higher efficacy of the VLPs in comparison with the soluble dimer and support VLP-cvD as a promising ZIKV vaccine. Author Summary Infection with Zika virus (ZIKV) leads to the production by host of antibodies that target the viral surface envelope (E) protein. A subset of these antibodies can inhibit virus infection, thus making E as a suitable candidate for the development of vaccine against the virus. However, the anti-ZIKV E antibodies can cross-react with the E protein of the related dengue virus on account of the high level of similarity exhibited by the two viral proteins. Such a scenario may lead to severe dengue disease. Therefore, the design of a ZIKV vaccine requires particular care. Here, we tested two candidate vaccines containing a recombinant form of the ZIKV E protein that is forced in a covalently stable dimeric conformation (cvD). They were generated with an explicit aim to reduce the exposure of the cross-reactive epitopes. One vaccine is composed of a soluble form of the E protein (sE-cvD), the other is a more complex virus-like particle (VLP-cvD). We used the two candidate vaccines to immunize mice and later infected with ZIKV. The animals produced high level of inhibitory antibodies and were protected from the infection. The VLP-cvD was the most effective and we believe it represents a promising ZIKV vaccine candidate.

Validation of an engineered Zika virus-like particle vaccine candidate in a mosquito-mouse transmission model

“…The lack of a visible manifestation of symptoms in A129 mice after infection with ZIKV PRVABC59 was unexpected since this strain is commonly used in ZIKV laboratory animal challenge models, usually with reported development of symptoms after an average infection with 10 4 pfu by subcutaneous injection (7, 33). A similar lack of development of clinical symptoms and lethality was also observed in A129 mice during the initial preliminary infection performed to set up the mosquito-mouse infection model (Sup Fig 1).…”

“…After homogenizing, 10-fold serial dilutions of each solution were transferred onto a monolayer of Vero-furin cells for viral quantification with FFA. Primary antibody for Zika was a Mouse Monoclonal antibody DIII1B (7); secondary antibody was the Goat anti-mouse Alexa Fluor 488, A-11001 (Thermo Scientific, Waltham, Massachusetts, USA). Celigo Imaging Cytometer (Nexcelom Bioscience, Lawrence, Massachusetts) was used for imaging plates.…”

“…We previously reported a candidate vaccine comprising ZIKV virus-like particles (VLPs) that have been engineered to display the viral envelope (E) protein locked into a stable dimeric conformation via a disulphide bridge (VLP-cvD)(7). This vaccine conferred protection against both Asian (PRVABC59) and African (MP1751) lineages of ZIKV in a mouse model through the generation of strongly neutralizing antibodies and dramatically reduced virus dissemination to organs, such as brain and testis.…”

“…During the past few years, several candidate vaccines have been developed and tested in preclinical stages (7-9) and the most promising ones have now moved to clinical trials (10, 11). Preclinical tests for ZIKV vaccine candidates are performed on murine or non-human primate (NHP) models.…”

Congenital Deafness and Recent Advances Towards Restoring Hearing Loss

“…Another explanation could be the presence of different strains of ZIKV with different levels of aggressiveness ( Russo, Jungmann, & Beltrao-Braga, 2017 ). Several vaccines and antiviral peptide therapies have been developed, and some vaccine candidates are currently in phase I of clinical trials to protect the population against the Zika virus ( Camargos et al, 2019 ; De Lorenzo et al, 2020 ; Trovato, Sartorius, D’Apice, Manco, & De Berardinis, 2020 ).…”