Advanced oxidation technology for the development of a next-generation inactivated West Nile virus vaccine

Abstract

West Nile virus (WNV) is the most frequent mosquito-borne disease reported in the continental United States and although an effective veterinary vaccine exists for horses, there is still no commercial vaccine approved for human use. We have previously tested a 3% hydrogen peroxide (H 2 O 2 )-based WNV inactivation approach termed, HydroVax, in Phase I clinical trials and the vaccine was found to be safe and modestly immunogenic. Here, we describe an advanced, nextgeneration oxidation approach (HydroVax-II) for the development of inactivated vaccines that utilizes reduced concentrations of H 2 O 2 in combination with copper (cupric ions, Cu 2+ ) complexed with the antiviral compound, methisazone (MZ). Further enhancement of this oxidative approach included the addition of a low percentage of formaldehyde, a cross-linking reagent with a different mechanism of action that, together with H 2 O 2 /Cu/MZ, provides a robust two-pronged approach to virus inactivation. Together, this new approach results in rapid virus inactivation while greatly improving the maintenance of WNV-specific neutralizing epitopes mapped across the three structural domains of the WNV envelope protein. In combination with more refined manufacturing techniques, this inactivation technology resulted in vaccine-mediated WNV-specific neutralizing antibody responses that were 130-fold higher than that observed using the first generation, H 2 O 2only vaccine approach and provided 100% protection against lethal WNV infection. This new approach to vaccine development represents an important area for future investigation with the potential not only for improving vaccines against WNV, but other clinically relevant viruses as well.

Arthritogenic Alphavirus Vaccines: Serogrouping Versus Cross-Protection in Mouse Models

“…Even the anti-GETV neutralizing responses generated by the GETV vaccine were relatively poor, perhaps suggesting that a very high dose or multiple vaccinations would be needed before cross-neutralizing responses to RRV are seen. The suboptimal induction of neutralizing antibody responses by a formalin-fixed vaccine [ 87 , 88 , 89 ] is perhaps supported herein by the observation that the ratios of neutralizing titers over ELISA titers were significantly higher for SCV-ZIKA/CHIK than for JEV/GETV vaccinations ( Supplementary Figure S8c , p < 0.0001). Generating cross-neutralizing responses with a formalin-fixed vaccine may thus represent a particularly difficult hurdle.…”

“…Given the 75% amino acid identity between RRV TT and GETV MI-110 ( Figure 5 i), the poor level of cross-protection ( Figure 5 d,h) might be viewed as somewhat unexpected. However, the JEV/GETV vaccine is formalin-fixed, a process known to reduce immunogenicity [ 87 ], potentially by altering the antigenic structure [ 88 ]. Formalin irreversibly modifies certain epitopes, particularly those containing lysine (K) and (to a lesser extent) tryptophan (W) residues [ 89 ].…”

An observer blinded, randomized, placebo-controlled, phase I dose escalation trial to evaluate the safety and immunogenicity of an inactivated West Nile virus Vaccine, HydroVax-001, in healthy adults

“…At day 180, the investigators performed a third vaccination and this resulted in antibody titers that were greatly improved over the first or second dose of vaccine and suggests that our vaccine approach could likewise be improved if a third dose of vaccine was administered on a similar vaccination schedule. In addition, a recent advance in peroxide-based inactivation technology represents another approach to improving future WNV vaccine design [37]. The first published use of 3% peroxide for virus inactivation/vaccine development was described in 2012 [25] and several improvements in oxidation-based virus inactivation have been developed since that time.…”

Viral Emerging Diseases: Challenges in Developing Vaccination Strategies

“…All the Envelope-based vaccines induced NAbs against both WNV lineages 1 and 2, but some candidates are unable to generate long-lasting antibody responses, requiring multiple administrations ( 103 , 108 , 109 ). Thus, further improvements are needed for the development of next-generation vaccines ( 110 ). Recently, a WNV replication-deficient vaccine candidate with a deletion of the non-structural protein NS1 has been shown to protect mice from a highly lethal viral challenge, after a single dose, without adverse effects ( 111 ).…”