147 Microwave-assisted drying of viruses: A new approach to enable vaccine transport and storage in the dry state

Abstract

Vaccines have had a profound effect on mortality reduction in both humans and animals throughout the world. The efficacy of live attenuated vaccines depends on the viability of the infectious biological agents of which they are comprised. Preservation is often achieved through refrigerated storage that must remain uncompromised from the site of production to the site of inoculation. Breaking the cold chain requirements for vaccines would not only reduce equipment and energy costs, but could increase the availability of live-attenuated vaccines throughout the world. The current work explores the utility of a microwave drying process to dehydrate a series of viruses for the ultimate purpose of storing them in a dry state. Vaccinia virus, an enveloped poxvirus, and an adenovirus, an icosahedral non-enveloped (“naked”) virus, were studied, as these DNA viruses have recently been shown to remain viable in a dehydrated state. Drying and storage studies were also performed on two enveloped RNA viruses, vesicular stomatis virus (VSV) and Sendai virus (SeV). All tested viruses have served as vaccine vectors. The primary objective was to demonstrate that viruses of relevance to vaccine production can be dried by microwave assisted processing and stored in a dry state while maintaining a suitable level of infectivity. Using microwave processing to achieve the dry state we were able to achieve long-term storage of vaccinia and an adenovirus (up to 3 months) at temperatures up to 45 °C. VSV and SeV were considerably less stable than the reference viruses, and could not be stored long-term without considerable loss of titer. These are enveloped viruses and thus likely to be more sensitive to processing stresses. Source of funding: This work was funded by a grant from the North Carolina Biotechnology Center. Conflict of interest: None declared. gdelliot@uncc.edu