Human cytomegalovirus preferentially infects early gestation placental macrophages and evades their antiviral immunogenicity through evasion of the type I IFN response

Abstract

Abstract Human cytomegalovirus (HCMV) is the leading cause of congenital viral infections. When a pregnant woman develops primary HCMV infection in early gestation, the risk of transplacental infection is ~40%. Studies have documented the presence of HCMV in placental macrophages (Hofbauer cells [HCs]) as a consequence of maternal viremia. However, the interplay between HCMV and placental macrophages (HCs) is poorly defined. With written informed consent, placentae were collected from 12 HIV-1/Hep B/HCMV seronegative women (>18 years). HCs were exposed to human HCMV (TB40/E). qPCR, FACS, ELISA, and Western blot analysis determined the expression of activation markers, cytokines, antiviral genes, and host proteins. Here we found that HCs isolated from early gestation (15–23 weeks) placentae are more susceptible to HCMV infection than HCs isolated from term (>39 weeks) placentae. HCMV infection of early gestation HCs led to a significant upregulation of activation markers, along with elevated secretion of proinflammatory cytokines, compared to HCMV-infected term HCs. In early gestation and term HC, HCMV rapidly induces the type I IFN pathway, leading to secretion of IFNs and strong induction of ISGs. However, HCMV diminishes type I IFN-mediated phosphorylation of STAT2, with early gestation HCs exhibiting the greatest level of inhibition. Our findings show that HCMV can subvert type I IFN signaling to support viral growth at the placenta, particularly during early gestation. Studying mechanisms used by viruses to prevent an immune response is of great importance for the development of new strategies to limit the sequelae of viral infections.