The FDA-Approved Drug Nelfinavir Inhibits Lytic Cell-Free but Not Cell-Associated Nonlytic Transmission of Human Adenovirus

Abstract

Adenoviruses (AdVs) are prevalent and give rise to chronic and recurrent disease. The human AdV (HAdV) species B and C, such as HAdV-C2, C5 and B14, cause respiratory disease, and constitute a health threat for immuno-compromised individuals. HAdV-Cs are well known for lysing cells, owing to the E3 CR1-β-encoded adenovirus death protein (ADP). We previously reported a high-throughput image-based screening frame-work and identified an inhibitor of HAdV-C2 multi-round infection, Nelfinavir mesylate. Nelfinavir is the active ingredient of Viracept, an FDA-approved inhibitor of the human immuno-deficiency virus (HIV) aspartyl protease, and used to treat acquired immuno-deficiency syndrome (AIDS). It is not effective against single round HAdV infections. Here, we show that Nelfinavir inhibits the lytic cell-free transmission of HAdV, indicated by the suppression of comet-shaped infection foci in cell culture. Comet-shaped foci occur upon convection-based trans-mission of cell-free viral particles from an infected cell to neighbouring uninfected cells. HAdV lacking ADP was insensitive to Nelfinavir, but gave rise to comet-shaped foci indicating that ADP enhances but is not required for cell lysis. This was supported by the notion that HAdV-B14 and B14p1 lacking ADP were highly sensitive to Nelfinavir, although HAdV-A31, B3, B7, B11, B16, B21, D8, D30 or D37 were less sensitive. Conspicuously, Nelfinavir unco-vered slow-growing round-shaped HAdV-C2 foci, independent of neutralizing antibodies in the medium, indicative of non-lytic cell-to-cell transmission. Our study demonstrates the repurposing potential of Nelfinavir with post-exposure efficacy against different HAdVs, and describes an alternative non-lytic cell-to-cell transmission mode of HAdV.

Recent Advances in Novel Antiviral Therapies against Human Adenovirus

“…In addition to various nucleic acid synthesis inhibitors, protease inhibitors have been evaluated against HAdV. Nelfinavir mesylate—the active ingredient of Viracept, which is an FDA-approved anti-HIV drug that functions by inhibiting the HIV aspartyl protease—was shown to prevent lytic egress and the cell-to-cell transmission of several HAdV types [ 139 ]. HAdV protease-specific inhibitors were identified by McGrath et al via structure-based drug design in silico [ 140 ].…”

Microscopy deep learning predicts virus infections and reveals mechanics of lytic-infected cells

“…Other capsids, for instance those from herpesviruses and baculoviruses, egress from the nucleus by engaging non-disruptive processes, including budding and fusion in the nuclear membranes ( Bigalke and Heldwein, 2016 ; Blissard and Theilmann, 2018 ; Wang et al., 2018 ; Zeev-Ben-Mordehai et al., 2015 ), although herpesviruses were also reported to rupture the NE, or dilatate nuclear pores ( Grimm et al., 2012 ; Klupp et al., 2011 ; Maric et al., 2014 ; Wild et al., 2019 ). The mechanisms of AdV egress from the nucleus have been difficult to explore, largely because of the unpredictable nature of the lysis process ( Georgi et al., 2020a ; Georgi and Greber, 2020 ; Prasad et al., 2020 ). Our machine learning protocols developed here combine live cell fluorescence microscopy with CNNs and prospectively identify infected nuclei programmed to undergo lytic AdV egress.…”

“…The onset of cell lysis overshadows non-lytic virus transmission, as shown recently with human adenovirus (AdV) ( Georgi et al., 2020a , 2020b ). Cell lysis has been observed with both enveloped and nonenveloped viruses.…”

“…It is exploited in clinical applications with oncolytic viruses, such as herpes simplex virus (HSV), measles virus, Newcastle disease virus, vaccinia virus, reovirus, parvovirus, coxsackie virus, polio virus, and AdV (reviewed in Lawler et al., 2017 ). Yet, lysis is difficult to detect by ultrastructural analyses, which provide snap-shots insights, although time-lapse fluorescence microscopy with single-cell resolution promises to directly visualize lytic events ( Georgi et al, 2020a ; Pied and Wodrich, 2019 ; Puntener et al, 2011 ; Wild et al, 2019 ; Yakimovich et al, 2012 ; Yamauchi et al, 2008a ).…”

Arrayed multicycle drug screens identify broadly acting chemical inhibitors for repurposing against SARS-CoV-2

“…Host targeting with chemical compounds combined with full cycle image-based analyses is a powerful approach against viral infections, as recently demonstrated with the identification of the HIV protease inhibitor Nelfinavir blocking human adenovirus egress from infected cells (13,14). Here we adapted a similar approach to identify broadly effective coronavirus inhibitors.…”