Single dose of a replication-defective vaccinia virus expressing Zika virus-like particles is protective in mice

Abstract

Zika virus (ZIKV), a flavivirus transmitted primarily by infected mosquitos, can cause neurological symptoms such as Guillian–Barré syndrome and microcephaly. We developed several vaccinia virus (VACV) vaccine candidates for ZIKV based on replication-inducible VACVs (vINDs) expressing ZIKV pre-membrane (prM) and envelope (E) proteins (vIND-ZIKVs). These vIND-ZIKVs contain elements of the tetracycline operon and replicate only in the presence of tetracyclines. The pool of vaccine candidates was narrowed to one vIND-ZIKV containing a novel mutation in the signal peptide of prM that led to higher expression and secretion of E and production of virus-like particles, which was then tested for safety, immunogenicity, and efficacy in mice. vIND-ZIKV grows to high titers in vitro in the presence of doxycycline (DOX) but is replication-defective in vivo in the absence of DOX, causing no weight loss in mice. C57BL/6 mice vaccinated once with vIND-ZIKV in the absence of DOX (as a replication-defective virus) developed robust levels of E-peptide-specific IFN-γ-secreting splenocytes and anti-E IgG titers, with modest levels of serum-neutralizing antibodies. Vaccinated mice treated with anti-IFNAR1 antibody were completely protected from ZIKV viremia post-challenge after a single dose of vIND-ZIKV. Furthermore, mice with prior immunity to VACV developed moderate anti-E IgG titers that increased after booster vaccination, and were protected from viremia only after two vaccinations with vIND-ZIKV.

Influence of Dosing Regimen and Adjuvant Type on the Immunogenicity of Novel Recombinant Zika Virus-Like Particles

“…The JEV prM protein signal peptide was also previously used with the VLPs of dengue virus ( 33 ). Moreover, substituting one amino acid in the prM signal sequence of ZIKV led to enhanced secretion of E protein, which was even higher than the protein level obtained with the use of the JEV signal peptide ( 16 ). In the case of the P2A peptide, this is the first report that used P2A in the flavivirus VLPs construct.…”

“…Naturally, two envelope glycoproteins of ZIKV, prM and E, are able to assemble into VLPs and are further secreted to the cell culture medium when expressed together in eukaryotic cells ( 14 ). However, the level of VLPs secretion may be low, and therefore different strategies, such as exchanging the signal sequence of prM protein or the transmembrane domains of E protein to analogous regions of Japanese encephalitis virus (JEV), have been used ( 15 , 16 ). Additionally, capsid protein (C) may be added to the VLPs construct to facilitate production; however, this strategy requires coexpression with viral protease to cleave the C protein from prM and E proteins.…”

Rendezvous with Vaccinia Virus in the Post-smallpox Era: R&D Advances

“…No plaque-forming virions could be recovered from ovaries of mice infected intraperitoneally with viP11A6L without DOX, while a significantly higher level of viral load was detected with DOX supplied in drinking water, to a level indistinguishable from WT VACV-infected mice. Another study adapting this strategy was published by the same group to confirm the feasibility of using a replication-inducible VACV as a vaccine vector for Zika virus (vIND-ZIKV) [ 50 ]. The vaccine did not lead to any weight loss or clinical signs in intranasally infected CB6F1 mice in the absence of DOX, indicating a consistent safety profile.…”

Are the Organoid Models an Invaluable Contribution to ZIKA Virus Research?

“…Interestingly, it has recently been shown that tetracycline-inducible vaccinia expressing prM and E protein induced high anti-E IgG titers in vitro; on the other hand, in vivo, mice treated with anti-IFNAR1 and vaccinated with a single dose were protected from ZIKV, with an increase of interferon-gamma (IFN-γ)-secreting splenocytes and the induction of a humoral response [80].…”