Immunology may be best taught by viruses ( 1 ), and possibly by humans ( 2 ), but the rats of New York City surprisingly also have plenty to offer. A survey published in 2014 of the pathogens carried by rats trapped in houses and parks in Manhattan identified a huge burden of infectious agents in these animals, including several novel viruses ( 3 ). Among these are Norway rat hepaciviruses (NrHVs), which belong to the same family as hepatitis C virus (HCV). NrHVs were found in rat livers, raising the possibility of establishing a small animal model of human HCV infection. On page 204 of this issue, Billerbeck et al. ( 4 ) fulfill this prediction.