Chloroquine, an Endocytosis Blocking Agent, Inhibits Zika Virus Infection in Different Cell Models

Delvecchio, Rodrigo; Higa, Luiza M.; Pezzuto, Paula; Valadão, Ana Luiza; Garcez, Patrícia P.; Monteiro, Fábio L.; Loiola, Erick C.; Dias, André A.; Silva, Fábio J. M.; Aliota, Matthew T.; Caine, Elizabeth A.; Osorio, Jorge E.; Bellio, Maria; O’Connor, David H.; Rehen, Stevens; de Aguiar, Renato Santana; Savarino, Andrea; Campanati, Loraine; Tanuri, Amilcar

Inhibition of viral infection mediated by chloroquine can occur in both the early and later stages of the viral replication cycle [30, 31] . To evaluate which step of the viral cycle was susceptible to inhibition, chloroquine was added to Vero cells at different time points post-infection with ZIKV MR766. The supernatant was collected 30 h post-infection and virus production was evaluated by relative quantification of viral RNA over the untreated control by RT-qPCR. Virus titers were also determined by plaque assay in Vero cells. Incubation of Vero cells with chloroquine at 0 h postinfection had a greater impact on the production of ZIKV particles, decreasing viral RNA 64-fold over the controls ( Figure 3A ). The addition of chloroquine from 30 min to 12 h post-infection was able to reduce virus release 9-20 fold over untreated, infected-cells. However, chloroquine added at 24 h post-infection had only a minor effect on viral production ( Figure 3A) . These results were confirmed by quantification of ZIKV infectious particles released after chloroquine treatment ( Figure 3B ). These data confirm that chloroquine interferes with the early stages of the ZIKV replication cycle.