Inhibitory Effect Of Silver Nanomaterials On Transmissible Gastroenteritis Virus-induced Host Cell Infections

Coronaviruses belongs to the family Coronaviridae, which primarily cause infection of the upper respiratory and gastrointestinal tract of hosts. Transmissible gastroenteritis virus (TGEV) is an economically significant coronavirus that can cause severe diarrhea in pigs. Vaccination has been extensively applied to prevent pigs from TGEV infection. However, the immune efficacy was not ideal and the potential dissemination as well as prevalence of infectious agent in piglets remains. To date, the understanding and knowledge regarding effective evaluation of chemical reagents on TGEV infection are limited. Therefore, development of preventive and therapeutic strategies is indispensible for control of TGEV infection.Silver nanomaterials (Ag NMs) have attracted great interests in recent years due to their excellent anti-microorganism properties. In this study, we used TGEV as a model of CoVs and comparatively evaluated the inhibitory effect of three different Ag NMs (Ag NPs, silver nanowires60nm, and silver nanowires400nm) on TGEV-mediated cell infection and apoptosis. The underlying molecular mechanism was further explored. Mitochondrial membrane potential (MMP), p38MAPK signal pathway activation, the expression of Bcl-2family proteins and the cleavage of the precursor caspase-3were measured. The main results are as follows:Herein, three representative Ag NMs including spherical Ag nanoparticles (Ag NPs, NM-300) and two kinds of silver nanowires (XFJ011) were selected to study their inhibitory effect on TGEV induced host cell infection in vitro. Ag NPs were uniformly distributed, with particle sizes less than20nm by characterization by environmental scanning electron microscope and transmission electron microscope. Two types of silver nanowires were60nm and400nm in diameter, respectively. TGEV infection induced the occurring of apoptosis in swine testicle (ST) cells, down-regulated the expression of Bcl-2, up-regulated the expression of Bax, altered mitochondrial membrane potential, activated p38MAPK signal pathway, and increased expression of p53as evidenced by immunofluorescence assays, real-time PCR, flow cytometry and Western blot.Under non-toxic concentrations, Ag NPs and silver nanowires significantly diminished the infectivity of TGEV in ST cells. Moreover, further results showed that Ag NPs and silver nanowires decreased the number of apoptotic cells induced by TGEV through regulating p38/mitochondria-caspase-3signaling pathway. Our data indicate that Ag NMs are effective in prevention of TGEV-mediated cell infection as a virucidal agent or as an inhibitor of viral entry and the present findings may provide new insights into antiviral therapy of coronaviruses.