Presence of Apis Rhabdovirus-1 in Populations of Pollinators and Their Parasites from Two Continents

Abstract

The viral ecology of bee communities is complex, where viruses are readily shared among co-foraging bee species. Additionally, in honey bees (Apis mellifera), many viruses are transmitted – and their impacts exacerbated – by the parasitic Varroa destructor mite. Thus far, the viruses found to be shared across bee species and transmitted by V. destructor mites are positive-sense single-stranded RNA viruses. Recently, a negative-sense RNA enveloped virus, Apis rhabdovirus-1 (ARV-1), was found in A. mellifera honey bees in Africa, Europe, and islands in the Pacific. Here, we describe the identification – using a metagenomics approach – of ARV-1 in two bee species (A. mellifera and Bombus impatiens) and in V. destructor mites from populations collected in the United States and Israel. We confirmed the presence of ARV-1 in pools of A. mellifera, B. impatiens, and V. destructor from Israeli and U.S. populations by RT-PCR and found that it can reach high titers in individual honey bees and mites (107–108 viral genomic copies per individual). To estimate the prevalence of ARV-1 in honey bee populations, we screened 104 honey bee colonies across Israel, with 21 testing ARV-1-positive. Tagged-primer-mediated RT-PCR analysis detected the presence of the positive-sense ARV-1 RNA in A. mellifera and V. destructor, indicating that ARV-1 replicates in both hosts. This is the first report of the presence of ARV-1 in B. impatiens and of the replication of a rhabdovirus in A. mellifera and V. destructor. Our data suggest that Varroa mites could act as an ARV-1 vector; however, the presence of ARV-1 in B. impatiens (which are not parasitized by Varroa) suggests that it may not require the mite for transmission and ARV-1 may be shared among co-foraging bee species. Given that ARV-1 is found in non-Apis bee species, and because “ARV” is used for the Adelaide River virus, we propose that this virus should be called bee rhabdovirus 1 and abbreviated BRV-1. These results greatly expand our understanding of the diversity of viruses that can infect bee communities, though further analysis is required to determine how infection with this virus impacts these different hosts.

Investigating the viral ecology of global bee communities with high-throughput metagenomics

“…One of these, Apis mellifera Rhabdovirus 1 (ARV-1), from the family Rhabdoviridae [6], was detected in A. mellifera populations in South Africa, Tonga, and the Netherlands. It was also recently identified in bee populations in Israel and the United States [55]. Our data sets related to this virus were published elsewhere [55] and thus we will only briefly summarize this information here.…”

“…It was also recently identified in bee populations in Israel and the United States [55]. Our data sets related to this virus were published elsewhere [55] and thus we will only briefly summarize this information here. We identified contigs corresponding to this Rhabdovirus in two different species (A. mellifera and Bombus impatiens) that were collected in Pennsylvania, United States, suggesting this virus can easily switch hosts.…”

“…Sequence homology analyses of these 29 novel virus contigs revealed 9 different viral families among these bee associated viruses, including 6 viral families that had not been heretofore observed in bees (noted in Supplementary Table 3). Of these, one virus from the family Rhaboviridae (BRV) was recently described in A. mellifera populations in the United States, Israel, South Africa, Tonga and the Netherlands, and B. impatiens populations in the United States [6,55]. Of the 29 novel virus contigs, 6 were found to contain a putative RdRp that could be used for phylogenetic analyses.…”

“…We identified contigs corresponding to this Rhabdovirus in two different species (A. mellifera and Bombus impatiens) that were collected in Pennsylvania, United States, suggesting this virus can easily switch hosts. Thus, Levin et al [55] proposed a different nomenclature, Bee Rhabdovirus (BRV). The two assembled contigs for each species were 13,844 nt and 14,589 nt in A. mellifera and B. impatiens respectively, and were >99% similar to ARV-1.…”

“…These assembled contigs contained the 5 genes that are typically carried by Rhabdoviruses, including the large protein (L), a glycoprotein (G), nucleoprotein (N), phosphoprotein (P), and matrix protein (M). Further information about this virus can be found in Levin et al [55].…”