PMC

(A) The preventive effect of chloroquine on Hantaan virus infection in newborn mice depicted by Kaplan-Meier survival plots. Mothers were treated daily with different concentrations of chloroquine for 16 days. Treatment started 2 days before birth. (○) PBS; (▵) 1 mg/kg chloroquine, (▪) 5 mg/kg chloroquine, (□) 10 mg/kg chloroquine. (B) The therapeutic effect of chloroquine on Hantaan virus infection in newborn mice. Symbols: (○) PBS; (□) mothers treated with daily doses of 10 mg/kg chloroquine started after infection (16.7% survival); (▵) mothers treated with 10 mg/kg chloroquine before birth of the pups (days -2 and -1, 12.5% survival); (●) pups treated daily with 10 mg/kg chloroquine subcutaneously (25% survival). Tx, therapeutic treatment; Px, prophylactic treatment.

Effect of chloroquine on FIPV infection in fcwf-4 cells and monocytes. (A) fcwf-4 cells were cultured with chloroquine for 1 h in the Post treatment group (gray bar), but not in the Pre/Post treatment group (black bar), followed by inoculation with FIPV at 37 °C. After 1 h, the supernatant was removed and cells were then treated with chloroquine at 37 °C in the Pre/Post treatment and Post treatment groups. After 1 day, the virus titer in the fcwf-4 cell culture supernatant was measured. n = 4. (B) Monocytes were cultured with chloroquine at 37 °C for 1 h in the Pre/Post treatment group, but not in the Post treatment group, followed by inoculation with FIPV at 37 °C. After 1 h, the supernatant was removed and cells were then treated with chloroquine at 37 °C in the Pre/Post treatment and Post treatment groups. After 1 day, the virus titer in the feline primary monocyte culture supernatant was measured. n = 8. ^∗∗p < 0.01 vs. without chloroquine (0 μM), ^∗p < 0.05 vs. without chloroquine (0 μM).

Effects of endosomal acidification in the replication of PEC or MNV-1. (A) LLC-PK cells were pre-treated with mock (medium) or chloroquine (70 µM) for 1 h, and infected with PEC (MOI 50) in the presence of mock or cholorquine. In all cells, GCDCA (100 µM) was present in the media to support virus replication during virus infection. Following virus infection, cells were thoroughly washed with PBS and fresh medium containing mock or chloroquine was added to the cells. Cells were then further incubated and collected at 12 h PI. In a separate experiment, chloroquine was added to the PEC-infected cells at 6 h PI and cells were collected at 12 h PI for the determination of viral replication by the TCID₅₀ assay. (B) RAW267.4 cells were pre-treated with mock (medium) or chloroquine (200 or 100 µM) for 30 min then infected with MNV-1 (MOI 10) in the presence of mock or chloroquine at 4 °C for 1 h. Cells were then washed with PBS and fresh medium containing mock or chloroquine was added to the cells for further incubation at 37 °C. At 4 h PI, cells were thoroughly washed again with PBS and fresh medium without chloroquine was added to the cells. Cells were collected at 12 h PI for the determination of virus replication by the TCID₅₀ assay. (C) Cells were pretreated with chloroquine (50 or 70 µM) for 30 min , and infected with MNV-1 (10 MOI) in the presence of mock or chloroquine at 4 °C for 1 h. Cells were then washed with PBS and fresh medium containing chloroquine was added to the cells. Cells were further incubated and collected at 12 h PI for determination of virus replication by the TCID₅₀ assay. (A–C) Asterisk indicates a significant reduction of viral titers in the treatment group compared to the control (P<0.05).

Survival of MA EBOV-inoculated mice (A) and hamsters (B) treated with CQ (90 mg/kg). C) Survival of MA EBOV–infected hamsters treated with a combination of CQ (50 mg/kg), doxycycline (2.5 mg/kg), and azithromycin (50 mg/kg). Combo, combination of chloroquine, doxycycline, and azithromycin; CQ, chloroquine; EBOV, Ebola virus; MA, mouse-adapted.