This document compares the production of dengue-2 virus in Vero cells under serum-containing and serum-free conditions. It found that the influence of multiplicity of infection (MOI) and time of infection (TOI) on virus titer varies between the two media. In the serum-containing medium, virus titer increased with both higher MOI and longer TOI. In the serum-free medium, virus titer increased with longer TOI but was constant with varying MOI. Overall, the serum-containing medium produced higher maximum virus titers than the serum-free medium.