The entry receptor LDLRAD3 is critical for Venezuelan equine encephalitis virus pathogenesis and neuroinvasion in mice

Abstract

Abstract Alphaviruses are enveloped positive-stranded RNA viruses of the Togaviridae family. Venezuelan equine encephalitis virus (VEEV) is an encephalitic alphavirus responsible for epidemics in equine and human populations across the Americas. Its potential for use as an aerosolized bioterrorism weapon and the demonstrated risk it poses in research settings highlight the need for countermeasures. VEEV pathogenesis is characterized by a systemic inflammatory response and central nervous system (CNS) infection, which can result in severe neurological complications and sequelae. Our laboratory identified a novel entry receptor for VEEV, low-density lipoprotein receptor class A domain containing 3 (LDLRAD3). Ldlrad3 −/−mice demonstrate reduced, but not abrogated, VEEV infection in target tissues and are resistant to disease and lethality. Here we define a critical role for LDLRAD3 in controlling VEEV tissue tropism and pathogenesis by studying the kinetics of infection in wild-type and Ldlrad3 −/−mice. Using detailed analyses of viral RNA levels, immunohistochemistry, flow cytometry, and primary neuronal cultures, we observed that VEEV infects LDLRAD3-expressing cell types as early as 6 h after inoculation and once in the CNS, preferentially targets neurons, and not glial cells, in a LDLRAD3-dependent manner. Overall, our studies define the role of LDLRAD3 in VEEV tropism and how LDLRAD3-dependent infection of LDLRAD3 contributes to the host inflammatory responses against VEEV. Finally, our studies demonstrate LDLRAD3-independent infection in Ldlrad3 −/−mice, which suggests the existence of alternate receptors for VEEV. These findings may be relevant for the generation of novel receptor-targeted antiviral therapies. NIAID F30AI164842