PRODUCTION OF PARVOVIRUS B19 VACCINE IN INSECT CELLS CO-INFECTED WITHDOUBLE BACULOVIRUSES

Recombinant human parvovirus B19 virus-like particles (VLPs), a candid ate vaccine, were produced using the insect cell (Sf-9)-baculovirus (A cNPV) expression system. The synthesis and assembly of the particles i n Sf-9 cells are directed by double infections with one recombinant vi rus (bacVP1) expressing the parvovirus minor viral protein VP1 and a s econd virus (bacVP2) expressing the major viral protein VP2. Previous animal studies demonstrated that the polypeptide composition of the VL Ps strongly affects the elicitation of virus neutralizing antibodies. The key factor controlling the production of an immunologically potent product in bioreactors was identified to be the multiplicity of infec tion (MOI) of bacVP1 and bacVP2 used for infection. A probabilistic mo del, which correlates well with the experimental results, was employed to facilitate the selection of MOIs and to provide a better understan ding of the baculovirus co-infection process. A novel production proce ss based on secondary infections was developed to ensure product consi stency and to simplify large-scale logistics. The effects of other cri tical process parameters, such as temperature, dissolved oxygen concen tration, lactate concentration, cell concentration at infection, and h arvest time, were also investigated. (C) 1996 John Wiley & Sons, Inc.