A genetically stable Zika virus vaccine candidate protects mice against virus infection and vertical transmission

Awadalkareem Adam,Camila R Fontes-Garfias,Pei-Yong Shi,Renat Ahatov,Antonio E Muruato,Yoseph Mahmoud,Binbin Wang,Steven G Widen,Vanessa V Sarathy,Samantha R Osman,Tian Wang,Emily Davis,Alan D T Barrett,Yang Liu,Huanle Luo,Wenqian Li,Chao Shan

doi:10.1038/s41541-021-00288-6

Awadalkareem Adam, Camila R Fontes-Garfias + Show 15 more

Open Access

https://doi.org/10.1038/s41541-021-00288-6

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Abstract

Although live attenuated vaccines (LAVs) have been effective in the control of flavivirus infections, to date they have been excluded from Zika virus (ZIKV) vaccine trials due to safety concerns. We have previously reported two ZIKV mutants, each of which has a single substitution in either envelope (E) glycosylation or nonstructural (NS) 4B P36 and displays a modest reduction in mouse neurovirulence and neuroinvasiveness, respectively. Here, we generated a ZIKV mutant, ZE4B-36, which combines mutations in both E glycosylation and NS4B P36. The ZE4B-36 mutant is stable and attenuated in viral replication. Next-generation sequence analysis showed that the attenuating mutations in the E and NS4B proteins are retained during serial cell culture passages. The mutant exhibits a significant reduction in neuroinvasiveness and neurovirulence and low infectivity in mosquitoes. It induces robust ZIKV-specific memory B cell, antibody, and T cell-mediated immune responses in type I interferon receptor (IFNR) deficient mice. ZIKV-specific T cell immunity remains strong months post-vaccination in wild-type C57BL/6 (B6) mice. Vaccination with ZE4B-36 protects mice from ZIKV-induced diseases and vertical transmission. Our results suggest that combination mutations in E glycosylation and NS4B P36 contribute to a candidate LAV with significantly increased safety but retain strong immunogenicity for prevention and control of ZIKV infection.

Highlights

Zika virus (ZIKV), is a re-emerging flavivirus of the family Flaviviridae, a group of single-stranded, positive-sense RNA viruses, which can be transmitted by mosquito bites, or by sexual contact[1,2,3]
We previously reported that ZIKV NS4B-P36A mutant has reduced neuroinvasiveness compared to the infectious clone derived wild-type (WT) ZIKV-FSS13025ic in mice deficient in IFN-α/β and IFN-γ receptors (AG129)[21]
Following infection in interferon-producing cells, such as A549 cells, ZE4B-36 generated significantly less virus at days 1 and 4 post infection than WT ZIKV-FSS13025ic, as determined by quantitative (Q)-PCR analysis (Fig. 1e) and focus-forming assay (FFA; Fig. 1f). These results indicate that stable ZE4B-36 mutant could be produced in cell culture and the mutant displayed lower replication kinetics

Summary

Introduction

Zika virus (ZIKV), is a re-emerging flavivirus of the family Flaviviridae, a group of single-stranded, positive-sense RNA viruses, which can be transmitted by mosquito bites, or by sexual contact[1,2,3]. The virus has caused more than one million human cases during the recent outbreaks in the Americas and Caribbean[4,5,6] and has been associated with severe neurological diseases, such as the autoimmune disorder Guillain-Barre syndrome in adults and congenital Zika syndrome (CZS) in fetuses and infants[7,8]. Adult women of child-bearing age, in particular pregnant women, are potential risk populations for ZIKV infection. No vaccines are currently approved for human use. The development of a safe, efficient vaccine with durable immunogenicity remains a high priority

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