title: The causes and consequences of changes in virulence following pathogen host shifts.
abstract: Emerging infectious diseases are often the result of a host shift, where the pathogen originates from a different host species. Virulence--the harm a pathogen does to its host-can be extremely high following a host shift (for example Ebola, HIV, and SARs), while other host shifts may go undetected as they cause few symptoms in the new host. Here we examine how virulence varies across host species by carrying out a large cross infection experiment using 48 species of Drosophilidae and an RNA virus. Host shifts resulted in dramatic variation in virulence, with benign infections in some species and rapid death in others. The change in virulence was highly predictable from the host phylogeny, with hosts clustering together in distinct clades displaying high or low virulence. High levels of virulence are associated with high viral loads, and this may determine the transmission rate of the virus.
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Ben
authors.initials: B
authors.lastname: Longdon
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Jarrod D
authors.initials: JD
authors.lastname: Hadfield
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Day
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Sophia C L
authors.initials: SC
authors.lastname: Smith
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: John E
authors.initials: JE
authors.lastname: McGonigle
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom; Department of Ecology, University of São Paulo, São Paulo, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Cogni
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Chuan
authors.initials: C
authors.lastname: Cao
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Jiggins
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000821:virology*; D058507:Host Specificity / Q000235:genetics*; D010802:Phylogeny; D012328:RNA Viruses / Q000472:pathogenicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load; D014774:Virulence / Q000235:genetics*