SARS-CoV-2 Short-Time Infection Produces Relevant Cytopathic Effects in Vero E6 Cell Line

Zupin, Luisa; Fontana, Francesco; Gratton, Rossella; Milani, Margherita; Clemente, Libera; Pascolo, Lorella; Ruscio, Maurizio; Crovella, Sergio

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is mainly transmitted through respiratory droplets from positive subjects to susceptible hosts or by direct contact with an infected individual. Our study focuses on the in vitro minimal time of viral absorption as well as the minimal quantity of virus able to establish a persistent infection in Vero E6 cells. We observed that 1 min of in vitro virus exposure is sufficient to generate a cytopathic effect in cells after 7 days of infection, even at a multiplicity of infection (MOI) value of 0.01. Being aware that our findings have been obtained using an in vitro cellular model, we demonstrated that short-time exposures and low viral concentrations are able to cause infection, thus opening questions about the risk of SARS-CoV-2 transmissibility even following short contact times.