Competitive Fitness in Coronaviruses Is Not Correlated with Size or Number of Double-Membrane Vesicles under Reduced-Temperature Growth Conditions

Al-Mulla, Hawaa M. N.; Turrell, Lauren; Smith, Nicola M.; Payne, Luke; Baliji, Surendranath; Züst, Roland; Thiel, Volker; Baker, Susan C.; Siddell, Stuart G.; Neuman, Benjamin W.

Brts105 was subjected to several tests to characterize its growth at 33°C and 40°C. The replication of Brts105 was compared to that of both the wild type and the better-characterized Brts31 mutant in primary mouse embryo fibroblast cells ( Fig. 2A) . Brts105 growth was slightly delayed compared to that of the wild type and Brts31 but reached a similar peak titer. Neither Brts105 nor Brts31 virus grew at 40°C (Fig. 2B) , and Brts105 did not produce RNA at 40°C (Fig. 2C) , demonstrating that growth of both viruses was temperature sensitive.