Twenty-five years of adaptation to a viral pandemic: RHDV and rabbits

When a novel pathogen arrives in a population it can lead to the emergence of a new infectious disease. Its impact may be especially severe because the host population has not evolved to resist or tolerate infection. Therefore, its long-term effects will depend on the ability of the host to adapt, which can rescue populations from decline or extinction. We propose the first long-term genetic study of how a vertebrate population adapts to a severe disease emergence event with the aim of providing fundamental insights into the evolutionary response of host populations to emerging diseases, and whether populations can be rescued by evolving to resist the new pathogen.

This is possible as we have access to a unique dataset and collection of samples. These were collected from a wild Australian population of rabbits over the 25 years following the release of the rabbit haemorrhagic disease virus (RHDV) as a biological control agent. During this time RHDV has killed most rabbits in the population, resulting in intense natural selection favouring increases in resistance. By combining newly generated genome sequences from 4000 rabbits with existing serological data on whether the rabbits survived RHDV infection, we can address fundamental questions about how a wild vertebrate population evolves in the face of a new emerging disease. To our knowledge, there is no comparable long-term genetic and epidemiological dataset that can be used to track the evolution of a natural vertebrate population in response to the emergence of a new and severe infectious disease.

First, we will examine whether populations evolved resistance, and the evolutionary processes that may have prevented this from happening. By estimating how genetically related the rabbits are to each other, we can quantify the amount of genetic variation in susceptibility to RHDV, which will determine the rate at which populations can adapt. However, in natural populations even when natural selection acts on a...