Unifying the spatial population dynamics and molecular evolution of epidemic rabies virus

Abstract

Infectious disease emergence is under the simultaneous influence of both genetic and ecological factors. Yet, we lack a general framework for linking ecological dynamics of infectious disease with underlying molecular and evolutionary change. As a model, we illustrate the linkage between ecological and evolutionary dynamics in rabies virus during its epidemic expansion into eastern and southern Ontario. We characterized the phylogeographic relationships among 83 isolates of fox rabies virus variant using nucleotide sequences from the glycoprotein-encoding glycoprotein gene. The fox rabies virus variant descended as an irregular wave with two arms invading from northern Ontario into southern Ontario over the 1980s and 1990s. Correlations between genetic and geographic distance suggest an isolation by distance population structure for the virus. The divergence among viral lineages since the most recent common ancestor correlates with position along the advancing wave front with more divergent lineages near the origin of the epidemic. Based on divergence from the most recent common ancestor, the regional population can be partitioned into two subpopulations, each corresponding to an arm of the advancing wave. Subpopulation A (southern Ontario) showed reduced isolation by distance relative to subpopulation B (eastern Ontario). The temporal dynamics of subpopulation A suggests that the subregional viral population may have undergone several smaller waves that reduced isolation by distance. The use of integrated approaches, such as the geographical analysis of sequence variants, coupled with information on spatial dynamics will become indispensable aids in understanding patterns of disease emergence.infectious disease ͉ isolation by distance ͉ landscape genetics

Landscape epidemiology of plant diseases

“…This may influence ecological and evolutionary genetics of pathogens and consequently the likelihood of disease (re)emergence. Analyses of causal mechanisms leading to disease emergence most often point out the simultaneous effects of ecological and evolutionary genetic changes in patterns of first appearance and spread (Real et al 2005). This is an important issue in agricultural production as illustrated by the overcoming of disease resistance of plants by a virulent pathogen strain (Parlevliet 2002) or the spread of resistance of pathogens to pesticides (Oerke & Dehne 2004).…”

Animal Rabies in Massachusetts, 1985–2006

“…The raccoon strain of rabies virus spread throughout the east coast of the United States following the importation of rabid raccoons into West Virginia from Florida in 1977 and has become a threat to human and domestic animals because of the close contact of raccoons with human habitat (Real et al, 2005). Thus far, there has been only one identified case of human rabies due to the raccoon virus variant (CDC, 2003).…”

“…Three major epizootics of rabies have occurred in Europe, Canada, and the United States since World War II; vectors have included the red fox (Vulpes vulpes), the arctic fox (Alopex lagopus), and raccoons (Procyon lotor), respectively (Real et al, 2005). The raccoon strain of rabies virus spread throughout the east coast of the United States following the importation of rabid raccoons into West Virginia from Florida in 1977 and has become a threat to human and domestic animals because of the close contact of raccoons with human habitat (Real et al, 2005).…”

A high-resolution genetic signature of demographic and spatial expansion in epizootic rabies virus

“…invasion ͉ phylogeography ͉ Procyon lotor ͉ wildlife disease ͉ zoonoses I nfectious diseases emerging in wildlife populations, and the concomitant threats to humans and domestic animals, continue to be a source of great public concern (1). Such emergences are often characterized by the spatial incursion of a pathogen into a completely susceptible host population (2)(3)(4). Opportunities to reduce or control the rate of spatial spread in wild animals are, unfortunately, usually quite limited.…”