ARS | Publication request: Genomic analyses of the microsporidian Nosema ceranae, an emergent pathogen of honey bees.

Submitted to: PLoS Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2009
Publication Date: June 10, 2009
Repository URL: http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000466
Citation: Cornman, R.S., Chen, Y., Schatz, M., Street, C., Zhao, Y., Desany, B., Egholm, M., Hutchison, S., Pettis, J.S., Lipkin, W.I., Evans, J.D. 2009. Genomic analyses of the microsporidian Nosema ceranae, an emergent pathogen of honey bees. PLoS Pathogens. 5(6):e1000466.

Interpretive Summary: Honey bees colonies are in decline in many parts of the world, in part due to pressures from a diverse set of parasites and pathogens. The presence of the fungal pathogen Nosema ceranae has increased significantly in the past decade, and this pest has been linked to colony losses. Here we describe the Nosema genome, and point to traits of this organism that help it parasitize bees. We provide the first genetic tools for understanding how Nosema ceranae interacts with bee hosts. These tools can be used to map the spread of this pest, identify and exploit weaknesses in the genome, and better understand how bees themselves combat Nosema disease. These genome resources will be used by researchers and regulators to reduce the impacts of a key honey bee pest.

Technical Abstract: Recent steep declines in honey bee health have severely impacted the beekeeping industry, presenting new risks for agricultural commodities that depend on insect pollination. Honey bee declines could reflect increased pressures from parasites and pathogens. The incidence of the microsporidian pathogen Nosema ceranae has increased significantly in the past decade. Here we present a draft assembly (7.86 MB) of the N. ceranae genome derived from pyrosequence data, including initial gene models and genomic comparisons with other members of this highly derived fungal lineage. N. ceranae has a strongly AT-biased genome (74% A+T) and a diversity of repetitive elements, complicating the assembly. Of 2,614 predicted protein-coding sequences, we estimate that 1,366 have homologs in the microsporidian Encephalitozoon cuniculi, the most closely related genome sequence that has been published. We identify conserved microsporidian-specific genes, which are of special interest as potential virulence factors. A surprising fraction of the diminutive N. ceranae proteome consists of novel and transposable-element proteins. For a majority of well-supported gene models, a conserved sense-strand motif can be found within 15 bases upstream of the start codon; a previously uncharacterized version of this motif is also present in E. cuniculi. These comparisons provide insight into the architecture, regulation, and evolution of microsporidian genomes, and will drive investigations into honey bee-Nosema interactions.