Israeli acute paralysis virus: epidemiology, pathogenesis and implications for honey bee health.

Yan Ping Chen,Wei Ping Chen,Dennis Vanengelsdorp,Yan Zhao,W Ian Lipkin,Jay D Evans,Jeffery S Pettis,Ji Lian Li,Miguel Corona,P Kirk Visscher,Ji Zhong Zhou,Humberto Boncristiani,Gloria Degrandi-Hoffman,Ai Fen Zhou,Gustavo Palacios,Huo Qing Zheng,Matthew Kramer,Shao Kang Huang,Xuan Zhang,Zhi Guo Li,Marla Spivak,Li You Wu,Congjun Li ,Michele Hamilton ,Keith S Delaplane ,Érica Weinstein Teixeira ,Myeong L Lee ,Francis A Drummond ,Barbara Smith ,Leellen F Solter

doi:10.1371/journal.ppat.1004261

Abstract

Israeli acute paralysis virus (IAPV) is a widespread RNA virus of honey bees that has been linked with colony losses. Here we describe the transmission, prevalence, and genetic traits of this virus, along with host transcriptional responses to infections. Further, we present RNAi-based strategies for limiting an important mechanism used by IAPV to subvert host defenses. Our study shows that IAPV is established as a persistent infection in honey bee populations, likely enabled by both horizontal and vertical transmission pathways. The phenotypic differences in pathology among different strains of IAPV found globally may be due to high levels of standing genetic variation. Microarray profiles of host responses to IAPV infection revealed that mitochondrial function is the most significantly affected biological process, suggesting that viral infection causes significant disturbance in energy-related host processes. The expression of genes involved in immune pathways in adult bees indicates that IAPV infection triggers active immune responses. The evidence that silencing an IAPV-encoded putative suppressor of RNAi reduces IAPV replication suggests a functional assignment for a particular genomic region of IAPV and closely related viruses from the Family Dicistroviridae, and indicates a novel therapeutic strategy for limiting multiple honey bee viruses simultaneously and reducing colony losses due to viral diseases. We believe that the knowledge and insights gained from this study will provide a new platform for continuing studies of the IAPV–host interactions and have positive implications for disease management that will lead to mitigation of escalating honey bee colony losses worldwide.

Highlights

Honey bees are the most economically valuable pollinators of agricultural crops worldwide
There is no single agent yet identified that causes Colony Collapse Disorder (CCD). It appears that CCD results from a combination of factors that include pathogens/parasites, pesticides, malnutrition, environmental stress, low genetic diversity, and migratory beekeeping practices
We investigated the molecular basis of pathogenesis, transmission and genetic diversity of Israeli acute paralysis virus (IAPV) in honey bees and evaluated the impacts of IAPV infection on colony losses

Summary

Introduction

Honey bees are the most economically valuable pollinators of agricultural crops worldwide. In the U.S alone, the value of agricultural crops pollinated by bees each year is more than $17 billion dollars [1]. Colony Collapse Disorder (CCD) was observed in U.S beekeeping operations. CCD is defined as an unusually sudden decrease in the numbers of worker honey bees, without expected signs of disease, starvation, or reproductive failure [2]. Such rapid declines have been observed throughout the history of beekeeping, and their causes often remain enigmatic.

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