Mitoxantrone Shows In Vitro, but Not In Vivo Antiviral Activity against Human Respiratory Syncytial Virus

Abstract

Human respiratory syncytial virus (HRSV) is the most common cause of severe respiratory infections in infants and young children, often leading to hospitalization. In addition, this virus poses a serious health risk in immunocompromised individuals and the elderly. HRSV is also a major nosocomial hazard in healthcare service units for patients of all ages. Therefore, the development of antiviral treatments against HRSV is a global health priority. In this study, mitoxantrone, a synthetic anthraquinone with previously reported in vitro antiprotozoal and antiviral activities, inhibits HRSV replication in vitro, but not in vivo in a mice model. These results have implications for preclinical studies of some drug candidates.

Keywords: HRSV; antivirals; bioluminescence; drugs.

Figure 1

Inhibitory effect of mitoxantrone on HRSV infection of HEP-2 cells. (A) The expression of recombinant red protein in the rrHRSV-infected cells in the presence of different drugs was measured by flow cytometry. The results are calculated as the mean of three independent experiments ± SD. **** indicated p-value < 0.0001. Representative FACS experiments showing uninfected cells (red) and rrHRSV-infected cells untreated (blue) or treated with mitoxantrone or the irrelevant drug sulfaguanidine at 100 μM (yellow) are depicted in panels (B,C), respectively.

Figure 2

Inhibitory dose–response curve to determine the IC50 for mitoxantrone on HRSV infection of HEP-2 cells. The expression of recombinant red protein in the rrHRSV-infected cells was measured by flow cytometry as Figure 1. The concentration-dependent inhibitory dose-curve data were plotted as percentage of inhibition normalized to uninfected cell controls with applied curve fits calculated using GraphPad Prism.

Figure 3

DNA topoisomerase inhibitors on HRSV infection of HEP-2 cells. The expression of recombinant red protein in the rrHRSV-infected cells in the presence of different DNA topoisomerase inhibitors was measured by flow cytometry as Figure 1. Mitoxantrone, doxorubicin, and etoposide are cellular DNA topoisomerase II inhibitors, whereas camptothecin, irinotecan, and topotecan are cellular DNA topoisomerase I inhibitors. The results are calculated as the mean of three independent experiments ± SD. **** indicated p-value < 0.0001.

Figure 4

In vivo luminescence of rHRSV-Luc-infected mice treated with mitoxantrone. Panel (A) Six Rag2 mice were infected i.n. at day 0 by rHRSV-Luc. Bioluminescence of untreated (blue) or treated with mitoxantrone (red) mice was measured by capture of photon emission from the nose at different days post infection using the IVIS system. The scale on the left indicates the average radiance: the sum of the photons per second from each pixel inside the region of interest/number of pixels (ps⁻¹ cm⁻² sr⁻¹). The results are calculated as the mean of three independent experiments ± SD. (A) Representative experiment is shown in panel (B).