CD14hi equine monocytes are preferential initial targets for infection with equine arteritis virus (IRC4P.615)

Abstract

Abstract Equine arteritis virus (EAV), the causative agent of equine viral arteritis (EVA) in horses, is distributed worldwide with clinical signs including an influenza-like illness in adult horses, abortion in pregnant mares, interstitial pneumonia in neonatal foals and persistent infection in genetically predisposed stallions. EAV is a small,enveloped virus with a positive-sense, single-stranded RNA genome and primarily infects epithelial and endothelial cells, plus unidentified subpopulations of monocytes and macrophages. The primary objective of this study was to identify the susceptible CD14+ monocyte subpopulation using a synthetic recombinant virus expressing mCherry derived from the prototypical virulent Bucyrus stain (VBS) of EAV. The recombinant virus had identical tropism to parental VBS supporting its use as a surrogate for EAV infection. Multi-color flow cytometric analysis showed that a minor population of CD14hi cells were preferentially infected by EAV at 12 h post infection (hpi), whereas by 36 hpi (three virus replication cycles) almost all infected monocytes were CD14lo. However, this CD14lo population was also characterized by expression of CXCL16, a molecule implicated in the establishment of persistent EAV infections in stallions. CXCL16 expression was not detected in CD14hi infected monocytes at 12 hpi. Work is in progress to determine the eventual differentiation status of CD14hi/CXCL16- and CD14lo/ CXCL16+monocyte populations in terms of M1/M2 polarization.