Global emergence and evolutionary dynamics of bluetongue virus

Moh A Alkhamis,Cecilia Aguilar-Vega,Kai Lin,Andres M Perez,Nicholas M Fountain-Jones,José M Sánchez-Vizcaíno

doi:10.1038/s41598-020-78673-9

Abstract

Bluetongue virus (BTV) epidemics are responsible for worldwide economic losses of up to US$ 3 billion. Understanding the global evolutionary epidemiology of BTV is critical in designing intervention programs. Here we employed phylodynamic models to quantify the evolutionary characteristics, spatiotemporal origins, and multi-host transmission dynamics of BTV across the globe. We inferred that goats are the ancestral hosts for BTV but are less likely to be important for cross-species transmission, sheep and cattle continue to be important for the transmission and maintenance of infection between other species. Our models pointed to China and India, countries with the highest population of goats, as the likely ancestral country for BTV emergence and dispersal worldwide over 1000 years ago. However, the increased diversification and dispersal of BTV coincided with the initiation of transcontinental livestock trade after the 1850s. Our analysis uncovered important epidemiological aspects of BTV that may guide future molecular surveillance of BTV.

Highlights

Bluetongue virus (BTV) epidemics are responsible for worldwide economic losses of up to US$ 3 billion
Our demographic reconstruction of BTV through time revealed that the approximate divergence time of the virus was inferred around 1000 years ago (Figs. 1A, 2A,C) using the segments 10 (S10) gene segment
We estimated that BTV has circulated in ungulate populations for at least 1000 years based on the S10 gene and potentially more than 2000 years based on the S6 analysis (Fig. 2A)

Summary

Introduction

Bluetongue virus (BTV) epidemics are responsible for worldwide economic losses of up to US$ 3 billion. Understanding the patterns of pathogen spread at a global scale is notoriously difficult This is the case for arthropod-borne multi-host viruses (hereafter arboviruses) that infect livestock. Bluetongue virus (BTV) is one arbovirus that infects livestock worldwide and is responsible for global losses of agriculture of up to US$ 3 b illion[2]. The geographical distribution of BTV outbreaks is shifting especially in Europe, where exotic and novel strains have been introduced from multiple continents[24,25,26]. Given the continuous emergence of novel BTV strains and the subsequent impact of their outbreaks on livestock populations worldwide, especially Europe, exploring the global evolutionary epidemiology of BTV is a critical element for designing risk-based intervention programs, such as identifying and targeting areas infected with emerging strains

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Conclusion