Hantavirus mutagenesis is impacted by mutagens and host antiviral proteins

Hantaviruses are emerging zoonotic viruses that infect humans with high fatality rates. We currently have a poor understanding of the processes that contribute to hantavirus mutagenesis and therefore the potential for viral adaptation. To understand the drivers of mutations in hantaviruses, we calculated and compared mutational spectra across 14 divergent hantavirus species. We found that mutagens that are conserved across host species have a major impact on hantaviruses mutagenesis, contributing to at least six of the 12 possible mutation types. We found differences in mutational signatures across hantaviruses, some of which may be due to variation in host mutagen levels that are known to influence somatic mutations. However, we could find no evidence for differential mutational signatures between viruses associated with distinct diseases in humans and no evidence of tissue tropism differences between reservoir hosts. Using a novel method to quantify the impact of ZAP-mediated selection, we found that ZAP greatly influences mutational patterns in transition mutation types across hantaviruses. We also find evidence that APOBEC family proteins drive mutagenesis in all hantaviruses, with the likely exception of Nova virus. Our results therefore provide strong support that mutagens and host antiviral proteins are major contributors to hantavirus mutagenesis, thereby generating the genetic diversity necessary for viral adaptation.