Modelling Vector Transmission and Epidemiology of Co-Infecting Plant Viruses.

Linda J S Allen,Michael J Jeger,Frédéric M Hamelin,Frank M Hilker,Nik J Cunniffe,Vrushali A Bokil

doi:10.3390/v11121153

Abstract

Co-infection of plant hosts by two or more viruses is common in agricultural crops and natural plant communities. A variety of models have been used to investigate the dynamics of co-infection which track only the disease status of infected and co-infected plants, and which do not explicitly track the density of inoculative vectors. Much less attention has been paid to the role of vector transmission in co-infection, that is, acquisition and inoculation and their synergistic and antagonistic interactions. In this investigation, a general epidemiological model is formulated for one vector species and one plant species with potential co-infection in the host plant by two viruses. The basic reproduction number provides conditions for successful invasion of a single virus. We derive a new invasion threshold which provides conditions for successful invasion of a second virus. These two thresholds highlight some key epidemiological parameters important in vector transmission. To illustrate the flexibility of our model, we examine numerically two special cases of viral invasion. In the first case, one virus species depends on an autonomous virus for its successful transmission and in the second case, both viruses are unable to invade alone but can co-infect the host plant when prevalence is high.

Highlights

Transmission is a key element in understanding the epidemiology of plant virus diseases, those transmitted by arthropod vectors [1,2,3,4]
Other aspects important for arthropod transmission include transovarial and transtadial transmission, and the “helper strategy” [3] in which a helper virus can be transmitted by the vector but the dependent virus can only be transmitted in the presence of the helper, a strategy modelled by Zhang et al [7]
Co-infections are pervasive in plant virus epidemiology; yet, mathematical models keeping track of co-infections often leave vector dynamics implicit

Summary

Introduction

Transmission is a key element in understanding the epidemiology of plant virus diseases, those transmitted by arthropod vectors [1,2,3,4]. Four modes of transmission, non-persistent, semi-persistent, persistent-circulative and persistent-propagative, can be distinguished. Each of these modes has a characteristic time period for acquisition from infected plants, retention in the vector, and inoculation to healthy plants [5], some virus groups such as the torradoviruses do not fit neatly into these categories [6]. Co-infection of hosts by two or more plant viruses is common in both agricultural crops [8,9]. The literature on co-infection by plant viruses

Methods

Results

Conclusion