Investigations on spreading of PRRSV among swine herds by improved minimum spanning network analysis

Péter Márton Szabó,István Szabó,Sándor Kecskeméti,Ádám Bálint,Dóra Szalay,Tamás Molnár

doi:10.1038/s41598-020-75516-5

Abstract

In Hungary, the economic losses caused by porcine reproductive and respiratory syndrome virus (PRRSV) led to the launching of a national PRRSV Eradication Program. An important element of the program was investigating the spread of PRRSV among swine herds and the possible ways of introduction by sequencing of the open reading frame 5 (ORF5) gene. However, the classical phylogenetic tree presentation cannot explain several genetic relationships clearly, while more precise visualization can be represented by network tree diagram. In this paper, we describe a practical and easy-to-follow enriched minimum spanning similarity network application for improved representation of phylogenetic relations among viral strains. This method eliminated the necessity of applying a predefined, arbitrary cut-off or computationally extensive algorithms. The network-based visualization allowed processing and visualizing large amount of data equally for the laboratory, private and official veterinarians, and helped identify the potential connections between different viral sequences that support data-driven decisions in the eradication program. By applying network analysis, previously unknown epidemiological connections between infected herds were identified, and virus spreading was analyzed within short period of time. In our study, we successfully built and applied network analysis tools in the course of the Hungarian PRRSV Eradication Program.

Highlights

In Hungary, the economic losses caused by porcine reproductive and respiratory syndrome virus (PRRSV) led to the launching of a national PRRSV Eradication Program
In Hungary, the prevalence of PRRSV infection and the economic losses led to the launching of a national PRRSV Eradication Program in 2014 that was based on territorial principles and was accepted by the EU competent veterinary health committee
Since network visualization is based on centrality metrics, and only the closely related sequences form a distinct cluster,clades connected with low bootstrap values in the classical phylogenetic tree were not present in the network

Summary

Introduction

In Hungary, the economic losses caused by porcine reproductive and respiratory syndrome virus (PRRSV) led to the launching of a national PRRSV Eradication Program. In order to successfully implement any eradication program, special attention has to be paid to investigating the spread of PRRSV among swine herds and the possible ways in which farms can become positive[11]. This plays a significant role in this phase of the eradication, and helps enhancing the biosecurity of the herds, thereby reducing the possibility of reinfection

Objectives

Methods

Results

Conclusion