Citrus leprosis complex is an emerging disease in the Americas, associated with two unrelated taxa of viruses distributed in South, Central, and North America. The cytoplasmic viruses are Citrus leprosis virus C (CiLV-C), Citrus leprosis virus C2 (CiLV-C2), and Hibiscus green spot virus 2, and the nuclear viruses are Citrus leprosis virus N (CiLV-N) and Citrus necrotic spot virus. These viruses cause local lesion infections in all known hosts, with no natural systemic host identified to date. All leprosis viruses were believed to be transmitted by one species of mite, Brevipalpus phoenicis. However, mites collected from CiLV-C and CiLV-N infected citrus groves in Mexico were identified as B. yothersi and B. californicus sensu lato, respectively, and only B. yothersi was detected from CiLV-C2 and CiLV-N mixed infections in the Orinoco regions of Colombia. Phylogenetic analysis of the helicase, RNA-dependent RNA polymerase 2 domains and p24 gene amino acid sequences of cytoplasmic leprosis viruses showed a close relationship with recently deposited mosquito-borne negevirus sequences. Here, we present evidence that both cytoplasmic and nuclear viruses seem to replicate in viruliferous Brevipalpus species. The possible replication in the mite vector and the close relationship with mosquito borne negeviruses are consistent with the concept that members of the genus Cilevirus and Higrevirus originated in mites and citrus may play the role of mite virus vector.

Viruses in the family Closteroviridae have a mono-, bi-or tripartite positive-sense RNA genome of 13-19 kb, and non-enveloped, filamentous particles 650-2200 nm long and 12 nm in diameter. They infect plants, mainly dicots, many of which are fruit crops. This is a summary of the ICTV Report on the family Closteroviridae, which is available at ictv. global/ report/ closteroviridae.

A Citrus volkameriana tree displaying symptoms similar to citrus leprosis on its leaves and bark was found in Hawaii. Citrus leprosis virus C (CiLV-C)-specific detection assays, however, were negative for all tissues tested. Short, bacilliform virus-like particles were observed by transmission electron microscopy in the cytoplasm of symptomatic leaves but not in healthy controls. Double-stranded (ds) RNAs ≈8 and 3 kbp in size were present in symptomatic leaf tissue but not in healthy controls. Excluding poly(A) tails, the largest molecule, RNA1, was 8,354 bp in length. The ≈3 kbp dsRNA band was found to be composed of two distinct molecules, RNA2 and RNA3, which were 3,169 and 3,113 bp, respectively. Phylogenetic analyses indicated that the RNA-dependent RNA polymerase (RdRp) domain located in RNA1 was most closely related to the RdRp domain of CiLV-C. A reverse-transcription polymerase chain reaction assay developed for the detection of this virus was used to screen nearby citrus trees as well as Hibiscus arnottianus plants with symptoms of hibiscus green spot, a disease associated with infection by Hibiscus green spot virus (HGSV). All nearby citrus trees tested negative with the assay; however, symptomatic H. arnottianus plants were positive. All three RNAs were present in symptomatic H. arnottianus and were >98% identical to the RNAs isolated from C. volkameriana. We contend that the virus described in this study is HGSV, and propose that it be the type member of a new virus genus, Higrevirus.

Mealybug wilt of pineapple (MWP) is one of the most destructive diseases of pineapple (Ananas comosus) worldwide. At least one Ampelovirus species, Pineapple mealybug wilt associated virus-2 (PMWaV-2), and mealybug feeding are involved in the etiology of MWP. A previously undescribed Ampelovirus sharing highest homology with PMWaV-1 and a putative deletion mutant sharing highest homology with PMWaV-2 were detected with reverse transcription-polymerase chain reaction (RT-PCR) assays using degenerate primers. Results were verified with additional sequence information and by immunosorbent electron microscopy. Sequence homology between the virus tentatively designated PMWaV-3, and PMWaV-1 and PMWaV-2, decreases toward the N-terminal across the HSP70 homolog, small hydrophobic protein, and RNA-dependent RNA polymerase open reading frames (ORF). Putative PMWaV-3 could not be detected with four different monoclonal antibodies specific for PMWaV-1 and PMWaV-2. The potential deletion mutant spanning the N-terminal of the HSP70 region was obtained from a pineapple accession from Zaire maintained at the USDA-ARS National Clonal Germplasm Repository in Hawaii. Putative PMWaV-3, like PMWaV-1 and PMWaV-2, is transmissible separately or in combination with other PMWaVs by Dysmicoccus brevipes and D. neobrevipes mealybugs. Plants infected with PMWaV-3 that were continuously exposed to mealybugs did not develop symptoms of MWP in the absence of PMWaV-2. Specific RT-PCR assays were developed for detection of putative PMWaV-3 and the deletion mutant.