Phylogeography of Equine Infectious Anemia Virus

Manuel Jara,Alba Frias-De-Diego,Gustavo Machado

doi:10.3389/fevo.2020.00127

Manuel Jara, Alba Frias-De-Diego + Show 1 more

Open Access

https://doi.org/10.3389/fevo.2020.00127

Copy DOI

Abstract

Equine Infectious Anemia virus (EIAV) is the causative agent of one of the most impacting infectious diseases affecting equids. EIAV is genetically diverse with several lineages circulating globally. To elucidate EIAV global spread patterns, we studied its spatiotemporal dynamics applying Bayesian phylodynamic analyses, using a worldwide compiled dataset composed of unique sequences of the gag gene. In addition, we performed a scoping review of 1.470 publications on EIAV to characterize the spatiotemporal trends in EAIV research. Phylogeographic reconstruction suggested Hungary as the most likely country of origin for current EIAV circulation (root state posterior probability = 0.21), and one of the most important centers of diversification for the disease. Historical EIAV spread was predominantly characterized by long-distance spread across continents. As a result, we found that the American and Asian circulating EIAV (i.e., Mongolia) are more related to European lineages than to other Asian countries, being Europe the continent with the highest EIAV phylogenetic diversity. Our bibliometric analysis showed a continuous increment in the number of publications per year, where the United States and China appeared as the countries with highest EIAV-related scientific production. This study provides a historical geographic mapping of the EIAV linages’ spread patterns. In addition, we identified important asymmetry between the current research effort and the availability of genetic data which restricted our abilities to quantify for example the time frame of virus dispersal.

Highlights

Equine infectious anemia (EIA) is a viral disease affecting equines that entails great economic losses worldwide mostly due to the obligatory elimination or isolation of infected animals (Montelaro et al, 1993; Souza, 2009; USDA, 2017)
We found a total of 297 Equine Infectious Anemia virus (EIAV) gag gene sequences from the 17 countries
Bayesian skyline plot (BSP) showed a steady pattern in the genetic diversity until around 1970, when there was a sharp increase in its effective population size, evidencing a constant decrease around mid-1990s follow another increase in diversity in early 2000 (Figure 1B)

Summary

Introduction

Equine infectious anemia (EIA) is a viral disease affecting equines that entails great economic losses worldwide mostly due to the obligatory elimination or isolation of infected animals (Montelaro et al, 1993; Souza, 2009; USDA, 2017). EIAV is currently one of the most significant infectious diseases of equids (Cook et al, 2013). It is caused by a lentivirus (EIAV) from the Retroviridae family (Leroux et al, 2004) known to be mostly transmitted by vectors from the family Tabanidae (Rojas, 1981; Barros and Foil, 2007). In the United States alone, the economic impact of EIAV has been estimated to be US $38 million, which may be much bigger in countries with higher horse-related industry, such as Brazil (Diniz et al, 2017), known to have the largest population of equids in Latin America (Oliveira et al, 2017).

Methods

Results

Conclusion