Background/Aims@#As the
coronavirus disease -2019 global
pandemic progresses,
screening of
antiviral agents effective against
severe acute respiratory syndrome coronavirus 2 (
SARS-CoV-2 ) is urgently needed. In addition, considering the
viral load kinetics of
SARS-CoV-2 , which peaks early in the illness, and the massive burden of the
disease , which may increase in the near
future , identifying well-tolerated oral
antivirals becomes increasingly important. We examined the
in vitro activity of
lopinavir /
ritonavir and
hydroxychloroquine on
SARS-CoV-2 , at concentrations which can be used to treat
coronavirus -19
patients with little concern of
toxicity . @*
Methods @#
Lopinavir /
ritonavir (7/1.75 μg/mL),
hydroxychloroquine base (1 or 2 μg/mL), or a combination thereof were administered 1 hour after the inoculation of
SARS-CoV-2 to
Vero cells at a multiplicity of
infection of 0.05. We examined cytopathic effects of
virus 48 hours after
administration of the respective
treatments and measured viral loads at three
time points (0, 24, and 48 hours post-
treatment ) by quantitative real-
time reverse-transcription
polymerase chain reaction , and compared the results obtained from the different
antiviral regimens tested. @*Results@#The severity of cytopathic effects was lower in
lopinavir /
ritonavir -treated
cells , and
viral load was significantly reduced in this group compared with the
control group (p < 0.001). However,
hydroxychloroquine did not show significant inhibitory effects on anti-
SARS-CoV-2 -mediated cytotoxicity or on
viral load at either concentration. @*Conclusions@#
Lopinavir /
ritonavir showed significant inhibitory effects on
SARS-CoV-2 in vitro at its usual
plasma concentration. However, the
in vitro antiviral activity of
hydroxychloroquine at concentrations commonly used in
humans was minimal, whether used alone or in combination with
lopinavir /
ritonavir .