Acute adenoviral cardiac infection elicits an arrhythmogenic substrate prior to inflammatory myocardial remodeling and myocarditis

Viral cardiac infection represents a significant clinical challenge encompassing several etiological agents, disease stages, complex presentation, and a substantial lack of mechanistic understanding. Myocarditis is a leading cause of sudden cardiac death in young adults, for which viral infection is the most common cause. Current knowledge in the field is dominated by later phases of disease, and the role of host immune responses in pathogenesis. However, little is known regarding how viral infection can acutely induce an arrhythmogenic substrate in the heart, and how this may create an already dangerous substrate prior to the immune response. Viruses are known to alter gap junction intercellular communication in various cell types, leading us to investigate the impact of infection on cardiomyocyte coupling and electrophysiology. Adenovirus is a leading cause of myocarditis, but due to species-specificity, models of infection are lacking and it is not understood how adenoviruses cause sudden cardiac arrest. Mouse Adenovirus Type-3 (MAdV-3) was recently isolated and reported to be cardiotropic, yet has not been utilized to understand mechanisms of cardiac infection and pathology in the research setting. We have developed MAdV-3 infection as a model to investigate acute cardiac infection and molecular alterations to the infected heart prior to an appreciable immune response or gross cardiomyopathy. By optical mapping we find decreases in conduction velocity concomitant with increased phosphorylation of Cx43Ser368, a residue known to regulate gap junction channel function. Additional to changes in gap junctions, patch clamping of MAdV-3-infected adult mouse ventricular cardiomyocytes reveals prolonged action potential duration as a result of decreased IK1 and IKs current density. Turning to human systems, we find that human adenovirus type-5 (HAdV-5) increases phosphorylation of Cx43Ser368 and disrupts calcium transients synchrony in human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), indicating common mechanisms with our mouse whole heart and adult cardiomyocyte data. Together, these findings demonstrate that adenoviral infection creates an arrhythmogenic substrate through direct targeting of gap junction and ion channel function in the heart. Such alterations are known to precipitate arrhythmias and likely contribute to sudden cardiac death in acutely infected patients, while preceding the pathological remodeling of subsequent myocarditis disease progression.