Abstract 16756: Coxsackievirus Infection During Early Pregnancy Leads to Congenital Heart Defects

Introduction: Coxsackievirus B (CVB), the most common cause of myocarditis, targets cardiomyocytes through the Coxsackie and Adenovirus Receptor which is highly expressed in the fetal heart. Association between maternal CVB infection and fetal cardiac malformations has not been studied. Hypothesis: CVB infection during early pregnancy may play a role in the pathogenesis of congenital heart disease (CHD). Methods: Pregnant C57Bl/6J mice were infected between embryonic days (E) 5-11 with CVB3 (Nancy strain) at doses 1x10 6 , 2.5x10 6 , and 5x10 6 TCID50. Presence of the virus was confirmed by RT-PCR and infectivity assay and quantified by qPCR. Fetal heart phenotype was assessed by histology and to determine changes at the molecular level after infection, RNA was collected from fetal hearts using laser microdissection and analyzed by RNA-Seq. The results were confirmed by immunohistochemistry and qPCR. To assess the potential clinical relevance of our observations in mice, we analyzed the sera from pregnant women for presence of antibody titers against of CVB. Results: Offspring of pregnant mice infected with CVB3 at different time points developed a spectrum of CHD (38.2%, n=78/204): ventricular septal defect, double outlet right ventricle, and non-compaction of the ventricular myocardium, along with fetal death. Infection at E9 led to the highest incidence of VSD compared to infection earlier (E5, E7 or E8) or later (E11) in gestation. Transcripts found to be differentially expressed between infected fetal hearts with VSDs compared with controls were mediators of the Transforming growth factor β and Extracellular matrix signaling pathways. Consistent with the former, expression levels of BMP2 and Smad1/5/9 mRNA were elevated. Simultaneously suppressed proliferation of cardiomyocytes in these fetuses was observed. Serum analysis from 66 pregnant women who had babies with heart defects showed elevated titers of antibodies against CVB underlining the clinical significance of CVB infection during pregnancy. Conclusions: In mice, there is a critical window during pregnancy where CVB infection leads to abnormal cardiac development, likely through reduction of cardiomyocyte proliferation mediated by elevated levels of BMP2 and Smad1/5/9. Collectively, the data confirm a link between CVB infection and CHD development in mouse and human.