Adenovirus Serotype 26 Cultivation on a Production Scale: Optimization of Conditions

Adenoviral vectors represent a safe and highly immunogenic platform for vaccine delivery. Non-replicating viral vectors are widely used in vaccinology due to properties such as high replicative activity, ease of manipulation, safety and immunogenicity, as well as scalability of their production and resistance to heat treatment procedures. In addition, vaccines based on adenoviral vectors induce sustained antigen-specific cellular and humoral immune responses. To elucidate the conditions for cultivating adenovirus vector serotype 26 (Ad26) in HEK293 cells, the effects of multiplicity of infection (MOI) on the cell maximum density, viability and productivity were investigated. As a result, optimal parameters for Ad26 cultivating were selected. The use of Ad26 at a dose in the range of (3.20‒4.16) × 109 hexon gene DNA copies to infect 1 L of HEK293 cell suspension allowed us to obtain viral material with a high yield of virus particles (about 2 × 1012/L). In addition, it was demonstrated that replacing glutamine in the nutrient medium with the more degradation-resistant dipeptide GlutaMAX™ (Thermo Fisher Scientific, USA) resulted in a decrease in cell doubling time to 22‒24 h while maintaining cell viability at 92‒98% during the exponential growth phase. Results obtained were used in the manufacture of the Ad26-component of the Gam-COVID-Vac vaccine, which made it possible to satisfy the high demand for the vaccine during the mass immunization campaign against COVID-19 in the Russian Federation.