Neurotropic Coronavirus Infections Stanley Perlman and D. Lori Wheeler Introduction/ Classifi cation Mouse hepatitis virus ( MHV) is a member of the Coronaviridae family in the order Nidovirales . Coronaviruses are classifi ed into one of three antigenic groups with MHV classifi ed as a lineage a betacoronavirus (de Groot et al. 2013 ) Members of the Coronaviridae family infect a wide range of species including humans, cows, pigs, chickens, dogs, cats, bats, and mice. In addition to causing clinically relevant disease in humans ranging from mild upper respiratory infection (e.g., HCoV [human coronavirus]- OC43 and HCoV-229E, HCoV-NL63, and HCoV-HKU1) to severe acute respiratory syndrome ( SARS ) and the Middle East Respiratory Syndrome ( MERS ) (Ksiazek et al. 2003 ; Peiris et al. 2003a ; Zaki et al. 2012 ), coronavirus infections in cows, chickens, and pigs exact a signifi cant annual economic toll on the livestock industry. MHV is a natural pathogen of mice that generally is restricted to replication within the gastrointestinal tract (Compton et al. 1993 ; Homberger et al. 1992 ). However, there exist several laboratory strains of MHV that have adapted to replicate effi ciently in the central nervous system (CNS) of mice and other rodents. Depending on the strain of MHV, virulence and pathology ranges from mild encephalitis with subsequent clearance of the virus and concomitant development of demyelination to rapidly fatal encephalitis. Thus, the neurotropic strains of MHV have proved to be useful systems in which to S. Perlman (*) • D. L. Wheeler Interdisciplinary Program in Immunology , University of Iowa , Iowa City , IA , USA Department of Microbiology , University of Iowa , BSB 3-712, 51 Newton Road , Iowa City , IA 52242 , USA e-mail: