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Identification of Brevipalpus yothersi Baker, as vector and possible primary host of cytoplasmic citrus leprosis viruses
A. ROY (1), J. S. Hartung (2), J. Shao (2), G. Leon (3), M. J. Melzer (4), J. J. Beard (5), G. Otero-Colina (6), G. R. Bauchan (2), R. Ochoa (2), R. H. Brlansky (7), W. L. Schneider (1). (1) USDA-ARS, Frederick, MD, U.S.A.; (2) USDA-ARS, Beltsville, MD, U.S.A.; (3) Centro de Investigación La Libertad, CORPOICA, Villavicencio, Colombia; (4) University of Hawaii, Honolulu, HI, U.S.A.; (5) Queensland Museum, South Brisbane, Australia; (6) Co

The citrus leprosis complex is one of the most important emerging viral threats to US citrus production. Several viruses are associated with leprosis, including <i>Citrus leprosis virus C</i>  (CiLV-C) and <i>Citrus leprosis virus C2</i> (CiLV-C2) (genus <i>Cilevirus</i>), <i>Hibiscus green spot virus 2</i> (HGSV-2), (<i>Higrevirus</i>), <i>Citrus leprosis virus N</i> (CiLV-N) and <i>Citrus necrotic spot virus</i>  (proposed genus <i>Dichorhavirus</i>). All leprosis viruses are transmitted by or associated with flat mites (<i>Brevipalpus</i> spp.). Suspected non-viruliferous and viruliferous <i>Brevipalpus</i> mites were collected from Colombian and Mexican leprosis-free and -infected citrus groves, respectively. <i>B. yothersi</i> from Colombia and Mexico and <i>B. californicus</i> from Mexico were identified as vectors of citrus leprosis, utilizing low temperature scanning electron microscopy. Conventional and reverse strand specific RT-PCR detection assays were developed to identify the viruses and assess replication in mites. All three major leprosis viruses (CiLV-C, -C2 and -N) as well as replication intermediates were detected from viruliferous <i>B. yothersi</i>. A circulative-persistent-propagative virus-vector relationship was established, corroborating phylogenetic analyses of the RNA-dependent RNA polymerase 2 domains and p24 gene amino acid sequences. Further analysis suggested that the <i>Cilevirus</i> and <i>Higrevirus</i> genera may have originated in mites, with <i>Citrus</i> spp. being a secondary host.

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