Contact inactivation of RNA and DNA viruses by N-methyl isatin beta-thiosemicarbazone and CuSO4

Development of a next-generation chikungunya virus vaccine based on the HydroVax platform

Chikungunya virus (CHIKV) is an emerging/re-emerging mosquito-borne pathogen responsible for explosive epidemics of febrile illness characterized by debilitating polyarthralgia and the risk of lethal infection among the most severe cases. Despite the public health risk posed by CHIKV, no vaccine is currently available. Using a site-directed hydrogen peroxide-based inactivation approach, we developed a new CHIKV vaccine, HydroVax-CHIKV. This vaccine technology was compared to other common virus inactivation approaches including β-propiolactone (BPL), formaldehyde, heat, and ultraviolet (UV) irradiation. Heat, UV, and BPL were efficient at inactivating CHIKV-181/25 but caused substantial damage to neutralizing epitopes and failed to induce high-titer neutralizing antibodies in vaccinated mice. HydroVax-CHIKV and formaldehyde-inactivated CHIKV retained intact neutralizing epitopes similar to live virus controls but the HydroVax-CHIKV approach demonstrated a more rapid rate of virus inactivation. HydroVax-CHIKV vaccination induced high neutralizing responses to homologous and heterologous CHIKV clades as well as to other alphaviruses including Mayaro virus, O’nyong’nyong virus, and Una virus. Following heterologous infection with CHIKV-SL15649, HydroVax-CHIKV-immunized mice were protected against viremia, CHIKV-associated arthritic disease, and lethal CHIKV infection by an antibody-dependent mechanism. In contrast, animals vaccinated with Heat- or UV-inactivated virus showed no protection against viremia in addition to demonstrating significantly exacerbated CD4⁺ T cell-mediated footpad swelling after CHIKV infection. Together, these results demonstrate the risks associated with using suboptimal inactivation methods that fail to elicit protective neutralizing antibody responses and show that HydroVax-CHIKV represents a promising new vaccine candidate for prevention of CHIKV-associated disease.

Chikungunya virus (CHIKV) is a mosquito-borne virus that has gained significant attention due to its ability to cause large epidemics and to spread beyond endemic countries through international travelers. Despite substantial efforts over the course of many years, a licensed CHIKV vaccine remains unavailable for protecting at-risk populations. Our research group has established an advanced site-directed oxidation system, termed HydroVax, for the development of new vaccines. Here, we describe a novel CHIKV vaccine that utilizes this peroxide-based vaccine platform and demonstrates greatly improved antiviral immunity compared to other traditional virus inactivation approaches as well as complete protection against viremia, CHIKV-associated arthritic disease and lethal CHIKV infection in robust preclinical mouse models. The HydroVax-CHIKV vaccine not only induced neutralizing antibodies to geographically diverse strains of CHIKV, but also elicited neutralizing antibody responses to other clinically important alphaviruses including, Mayaro, O’nyong’nyong, and Una virus. Together, this indicates that this vaccine not only protects against CHIKV infection but may potentially provide immunity across a broader range of virulent alphaviruses as well.

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

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 (H₂O₂)-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, next-generation oxidation approach (HydroVax-II) for the development of inactivated vaccines that utilizes reduced concentrations of H₂O₂ in combination with copper (cupric ions, Cu²⁺) 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 H₂O₂/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, H₂O₂-only 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.

Picornavirus inhibitors

Picornaviruses are among the best understood animal viruses in molecular terms. A number of important human and animal pathogens are members of the Picornaviridae family. The genome organization, the different steps of picornavirus growth and numerous compounds that have been reported as inhibitors of picornavirus functions are reviewed. The picornavirus particles and several agents that interact with them have been solved at atomic resolution, leading to computer-assisted drug design. Picornavirus inhibitors are useful in aiding a better understanding of picornavirus biology. In addition, some of them are promising therapeutic agents. Clinical efficacy of agents that bind to picornavirus particles has already been demonstrated.

Zinc, copper, and manganese in immune function and experimental oncogenesis

Dietary deficiency of trace metals among human populations, once thought to be exceedingly rare, has recently gained attention as a potential public health problem. The consumption of highly refined and heavily processed foods reduces the trace element content of the diet. The higher trace element requirements of pregnancy, lactation, growth, development, and chronic disease may further contribute to states of marginal trace metal nutriture. Experimental animal studies have demonstrated that even marginal trace element deprivation during critical periods of growth and development or, alternately, during prolonged deficiency in adults can significantly alter immunologic function. Furthermore, trace metal nutriture has been shown to affect initiation and progression of a large variety of neoplasia. Studies of the interaction of trace metal nutriture and cancer have, however, suffered from many methodological inconsistencies as well as failures to define and quantitate the trace element content of diets and the host alterations in response to neoplastic challenge. Similarly, there has been little information in the critical area of marginal and moderate trace metal deficiency, i.e., those experimentaL situations most analogous to deficiencies that may occur in human populations. In this review, an attempt is made first to place in perspective experimental data relevant to these issues, and second to emphasize the desirability of further investigation in this critical area of human nutrition.