Table 1.

Examples of factors contributing to the recruitment of new host species

Event	Virus	Reference
Mutations that facilitate the use of alternative receptors in the newly adopted host species	Feline parvovirus	29
Transmission to humans after occupational exposure	Hendravirus	135
Intensified contact between natural and new host species due to climatic changes	Hantavirus	136
Immune evasion by genetic variation (e.g. antigenic drift and shift)	Influenza virus	55
Introduction in new geographic areas by migrating birds	West Nile virus	137
Initial close contact between natural and newly adopted host due to changes in natural infrastructures	Nipah virus	135

This article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency.