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 resulting lack of mechanistic understanding. Myocarditis is a leading cause of sudden cardiac death in young adults, where current knowledge in the field is dominated by later disease phases, and pathological host immune responses. However, little is known regarding how viral infection can acutely induce an arrhythmogenic substrate prior to significant immune responses. Adenovirus is a leading cause of myocarditis, but due to species-specificity, models of infection are lacking and it is not understood how adenoviral infection may underlie sudden cardiac arrest. Mouse Adenovirus Type-3 (MAdV-3) was previously reported as cardiotropic, yet has not been utilized to understand mechanisms of cardiac infection and pathology. 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 of infected hearts we find decreases in conduction velocity concomitant with increased Cx43Ser368 phosphorylation, a residue known to regulate gap junction function. Hearts from animals harboring a phospho-null mutation at Cx43Ser368 are protected against MAdV-3 induced conduction velocity slowing. Additional to gap junction alterations, 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 human adenovirus type-5 (HAdV-5) increases phosphorylation of Cx43Ser368 and disrupts 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. Overall design: To determine transcriptomic changes in the cardiac ventricles following mouse adenovirus type-3 (MAdV-3) infection, cardiac ventricles were collected from 3 mock-infected mice and 3 MAdV-3-infected mice at 7 days post infection. Snap-frozen ventricles were sent to GeneWiz for RNA-seq processing. Gene expression in MAdV-3-infected ventricles were compared to that of mock-infected ventricles.