|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.