YY-EEID US-UK The evolutionary ecology of pathogen emergence via cross-species transmission in the avian-equine influenza system

Viral emergence poses a constant threat to humans and animals and we are neither able to predict which viruses will emerge, nor where, when, or which populations will be affected. The overall aim of this project is to determine how environmental, host, and virus factors influence host-pathogen interactions and transmission dynamics of potentially emerging viruses. Avian influenza viruses (AIVs) provide unique opportunities to address this because they have jumped into humans, dogs, pigs and horses, with significant consequences on public health, food security, and the global economy. We will focus on the transmission and emergence of AIVs to horses because AIV strains have emerged in horse populations on independent occasions. We propose to perform field work in a well-defined ecosystem that favours avian-to-horse AIV transmission and also to perform laboratory experiments using avian and equine influenza viruses with different levels of "equine fitness" - ability to infect and transmit in horses. Our laboratory experiments will use genetic engineering to capture changes in fitness due to virus evolution. Results obtained will be combined in a mathematical framework that will enable the estimation of risk of viral emergence, including the effects of herd immunity. This multidisciplinary research will provide new insights on the mechanisms that underpin viral emergence and will aid the design of more effective intervention measures to control future events of viral emergence.