The genome sequences of baculoviruses from the tufted apple bud moth, Platynota idaeusalis, reveal recent recombination between an alphabaculovirus and a betabaculovirus from the same host

Authors: Harrison, Robert; JANSEN, ANDREW - US Department Of Agriculture (USDA); FIFE, AUSTIN - US Department Of Agriculture (USDA); Rowley, Daniel

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2025
Publication Date: 1/30/2025
Citation: Harrison, R.L., Jansen, A.M., Fife, A.N., Rowley, D.L. 2025. The genome sequences of baculoviruses from the tufted apple bud moth, Platynota idaeusalis, reveal recent recombination between an alphabaculovirus and a betabaculovirus from the same host. Viruses. 17. Article e202. https://doi.org/10.3390/v17020202.
DOI: https://doi.org/10.3390/v17020202

Interpretive Summary: The tufted apple bud moth is an insect pest that can damage apple crops in the mid-Atlantic region when larvae of the moth are numerous. Baculoviruses are natural disease-causing agents of moth larvae that have been formulated as environmentally safe bio-insecticides which can be used against moth pests instead of chemical insecticides. Previously, two baculoviruses were discovered causing disease in tufted apple bud moth larvae, but little was known about these viruses. To further characterize these viruses, ARS scientists in Beltsville, Maryland determined their genome sequences and found that these viruses both represented new species of baculoviruses. One of these viruses had acquired genetic material from the other virus, suggesting that individual moth larvae may be infected with both viruses at the same time. The information in this study contributes to progress towards identifying baculoviruses suitable for development as bio-insecticides, and will be of interest to those in academia, government, and industry who work with this group of insect viruses or with moth pests like the tufted apple bud moth.

Technical Abstract: The USDA-ARS collection of insect viruses at Beltsville, MD, USA contains samples of an alphabaculovirus from larvae of the tufted apple bud moth, Platynota idaeusalis Walker, as well as a presumptive betabaculovirus from the same host species. The viruses in these samples - Platynota idaeusalis nucleopolyhedrovirus isolate 2680 (PlidNPV-2680) and Platynota idaeusalis granulovirus isolate 2683 (PlidGV-2683) - were characterized by electron microscopy of their occlusion bodies (OBs) and determination and analysis of their genome sequences. Scanning and transmission electron microscopy of the OBs revealed morphologies typical for alphabaculoviruses and betabaculoviruses. Sequencing of viral DNA resulted in circular genomes of 121,881 bp and 106,633 bp for PlidNPV-2680 and PlidGV-2683, respectively. Similar numbers of ORFs (128 for PlidNPV-2680, 125 for PlidGV-2683) were annotated, along with ten homologous regions (hrs) in the PlidNPV-2680 genome and five intergenic regions of tandem direct repeats (drs) in the PlidGV genome. Phylogenetic inference from core gene alignments suggested that PlidMNPV-2680 represents a unique lineage within genus Alphabaculovirus, while PlidGV-2683 was grouped with clade b betabaculoviruses. Comparison of the PlidNPV-2680 and PlidGV-2683 genomes revealed a 1,516-bp region in PlidNPV-2680 that exhibited 97.5% sequence identity to a region of the PlidGV-2683 genome, suggesting that recombination had occurred recently between these viruses.