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Title: Role bending: complex relationships between viruses, hosts and vectors related to citrus leprosis, an emerging disease

item ROY, AVIJIT - University Of Florida
item Hartung, John
item Schneider, William
item Shao, Jonathan
item LEON, GUILLERMO - Corpoica
item MELZER, MICHAEL - University Of Hawaii
item BEARD, JENNIFER - Queensland Museum
item OTERO-COLINA, GABRIEL - Colegio De Postgraduados
item Bauchan, Gary
item Ochoa, Ronald - Ron
item BRLANSKY, RONALD - University Of Florida

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2015
Publication Date: 6/15/2015
Publication URL:
Citation: Roy, A., Hartung, J.S., Schneider, W.L., Shao, J.Y., Leon, G.M., Melzer, M.J., Beard, J.J., Otero-Colina, G., Bauchan, G.R., Ochoa, R., Brlansky, R.H. 2015. Role bending: complex relationships between viruses, hosts and vectors related to citrus leprosis, an emerging disease. Phytopathology. DOI: 10.1094/PHYTO-12-14-0375-FI.

Interpretive Summary: Citrus leprosis is an emerging disease threat in South and Central America. Recent spread in Mexico suggests leprosis may soon threaten the U.S. citrus industry. The viruses that cause these diseases are spread by mites. Viral infection results in loss of production and potentially death of the infected trees. The leprosis issue is compounded by the fact that natural reservoirs of the virus have never been identified. Researchers from USDA-ARS laboratories in Ft. Detrick and Beltsville MD, the University of Florida, CORPOICA, Colombia, the University of Hawaii, the Queensland Museum, Brisbane Australia, and the Colegio de Postgraduados, Mexico conducted studies to describe the current spread of the disease and the mites that spread the disease. Researchers from these organizations have determined previously unkown hosts, as well as discovering the viruses that cause leprosis may actually be insect viruses, not plant viruses. This knowledge helps regulatory efforts by focusing disease control efforts on the mites in specific geographic locations, allowing for maximum leveraging of resources.

Technical Abstract: Citrus leprosis is a difficult viral disease causing significant damage to citrus fruit in South America and Central America. The disease is marked by dramatic lesions on fruit, leaves and stems, resulting in an unmarketable product. The disease is caused by a set of unrelated cytoplasmic cileviruses (Citrus leprosis virus -C, and Citrus leprosis virus -C2) and nuclear dichorhabdoviruses (Citrus leprosis virus –N). These viruses are transmitted by mites, as are the related higreviruses (Hibiscus Greenspot virus). These viruses have no systemic plant hosts, which is a very unique situation among plant viruses. These viruses are spreading northward through Mexico, presenting a threat to the U.S citrus industry. This paper describes a comprehensive survey effort that maps the current epidemiological status of the virus and identifies a number of new hosts. A close examination of the mites associated with infection outbreaks has allowed for a correction of the taxonomic classification of the potential vectors. The sequence data generated from genomic studies was studied to determine evolutionary relationships within these viruses, as well as relationships to other viruses. Interestingly, the cytoplasmic cileviruses were more closely related to insect viruses than other plant viruses. Reverse-transcription PCR was used to demonstrate that both the cytoplasmic and the nuclear leprosis related viruses replicate in the mite. This raises the possibility these viruses are actually insect viruses that have convergently evolved a very unique method of using plants as a means to transmit virus from mite to mite.