Positive correlations in susceptibility to a diverse panel of viruses across Drosophilidae host species

Our ability to predict the emergence of novel viruses relies on there being generalizable patterns in the susceptibilities of hosts to novel infections. Studies investigating variation in susceptibility among host species have consistently shown that closely related hosts share similar susceptibilities to a given virus. However, the extent to which such phylogenetic patterns of susceptibility are correlated among diverse sets of viruses is unclear. Here, we investigate phylogenetic correlations in susceptibility among Drosophilidae hosts to a panel of 11 different invertebrate viruses, comprising 7 unique virus species, 6 unique families, and both RNA and DNA viruses. The susceptibility of hosts to each pair of viruses tested was either positively correlated across host species or did not show evidence of correlation. No negative correlations, indicative of evolutionary trade-offs in host susceptibility to different viruses, were detected between any virus pairs. The strength of correlations was generally higher in viruses of the same species and family, consistent with virus phylogenetic patterns in host infectivity. Our results suggest that generalized host susceptibility can result in positive correlations, even between highly diverged viruses, while specialized interactions with individual viruses cause a stepwise decrease in correlation strength between viruses from the within-species, to the within-family, and to the across-family level.