Emerging infectious diseases are a significant threat to public health. Many new and exciting platforms have been developed in recent years, but cold chain requirements significantly limit patient access in all areas of the world, specifically the developing world. Recombinant vesicular stomatitis virus (rVSV) has been identified as an ideal viral vaccine platform due to fast production, inability for RNA genome to integrate into host genome, mild pathogenicity, and induction of humoral and cellular immune responses1. rVSV efficacy has been demonstrated with the development of an Ebola vaccine (ERVEBO)2. However, thermal instability of rVSV vaccines is the major limitation. ERVEBO must be stored between -60 oC to -80oC requiring an expensive and complex cold chain for distribution2.
Elarex has developed a stabilization technology PT120-D that has been demonstrated to stabilize viral vector vaccines at 40oC for up to 12 weeks and maintain 100% efficacy compared to storage at -80oC3. Utilizing a combination of pullulan and trehalose carbohydrates, the viral vector is dried yielding a thermal stable film for functional stability. Both pullulan and trehalose are considered GRAS, making them amenable to human therapeutic formulations.
The application of the PT120-D formulation to rVSV results in a substantial increase to the thermal stability of the virus. Previous work demonstrated up to 2 log titer loss of VSV within 24 hours in solution at 40oC4. Our data has shown rVSV dried without PT120-D is not detectable after 7 days at 37oC (9 log loss). In contrast, rVSV dried with PT120-D formulations had less then a 2-log loss after 18 days incubated at 37oC. This represents a significant improvement in the thermal stability of rVSV, with long-term studies are underway to fully characterize PT120-D stabilization capabilities.
