Joá yellow blotch-associated virus, a new alphanucleorhabdovirus from a wild solanaceous plant in Brazil.

We identified a novel plant rhabdovirus infecting native joá (Solanum aculeatissimum) plants in Brazil. Infected plants showed yellow blotches on the leaves, and typical enveloped bacilliform rhabdovirus particles associated with the nucleus were seen in thin sections by electron microscopy. The virus could be graft-transmitted to healthy joá and tomato plants but was not mechanically transmissible. RT-PCR using degenerate plant rhabdovirus L gene primers yielded an amplicon from extracted total RNA, the sequence of which was similar to those of alphanucleorhabdoviruses. Based on close sequence matches, especially with the type member potato yellow dwarf virus (PYDV), we adopted a degenerate-primer-walking strategy towards both genome ends. The complete genome of joá yellow blotch-associated virus (JYBaV) is comprised of 12,965 nucleotides, is less than 75% identical to that of its closest relative PYDV, and clusters with PYDV and other alphanucleorhabdoviruses in L protein phylogenetic trees, suggesting that it should be taxonomically classified in a new species in the genus Alphanucleorhabdovirus, family Rhabdoviridae. The genome organization of JYBaV is typical of the 'PYDV-like' subgroup of alphanucleorhabdoviruses, with seven genes (N-X-P-Y-M-G-L) separated by conserved intergenic regions and flanked by partly complementary 3' leader and 5' trailer regions.

Strongylodon macrobotrys: new host of soybean mosaic virus in Brazil.

Strongylodon macrobotrys, commonly known as the jade vine, emerald vine, or turquoise jade vine, is a species of Fabaceae native to the Philippines. The plants have blue-green color inflorescences, which makinge them one of the most admired ornamental plants in Brazil (Muniz et al. 2015). In addition, the plants contain compounds with anticancer properties (Ragasa et al. (2014) isolated compounds from S. macrobotrys with anticancer properties. In March 2019, an adult jade plant, grown under the trellis system in an experimental area at the campus of the University of São Paulo (USP), Piracicaba, state of São Paulo, was found showing mosaic symptoms typical of a virus infection. Preliminary examination of negatively stained leaf extracts by transmission electron microscopy detected elongated, flexuous particles similar tolike thoseat of a potyviruses. Further observations of thin sections of symptomatic leaf tissues revealed the presence of cylindrical inclusions, as well as bundles of thin, elongated, and filamentous particles, typical of potyvirus infection in epidermal, parenchymalparenchymal, and vascular regions, as well as bundles of thin, elongated and filamentous particles. Subsequent molecular and biological assays confirmed the presence of a potyvirusTo identify the species of the virus, .Presence of a potyvirus was confirmed by subsequent molecular and biological assays. Ttotal RNA was extracted from a pool of symptomatic leaves from the plant using the Purelink viral RNA/DNA kit (Thermo Fisher Scientific), and analyzed by one- step RT-PCR using potyviruses universal primers PV1/SP6 and WCIEN-sense (Mackenzie et al. 1998; Maciel et al. 2011), which amplify a 750-bp fragment. Total RNA extracted from an asymptomatic jade vine, obtained from a florist shop, was used as a negative controlincluded in the assay. PCR products at the expected size (~750-bp) were observed in the symptomatic plant but not in the asymptomatic plant. BLASTn analysis of the Nnucleotide sequence of the amplicon obtained only from total RNA of the symptomatic plant (GenBank accession no. MN970030) showed that it shares 90.82% to 97.859% identity with corresponding nucleotide sequences of the Korean isolate WS162 of soybean mosaic virus (SMV) deposited at the GenBank (, accession no. FJ640973, FJ640956, D88616). Extracts from symptomatic leaves of the jade plant wereas mechanically inoculated onto leaves of healthy plants of jade vine, Jack bean (Canavalia ensiformis), soybean cv. NA 5909 (Glycine max), cowpea (Vigna unguiculata), and passion fruit (Passiflora edulis f. flavicarpa). One plant of jade plant and four plants of each other species were inoculated , and infection was assessed based and monitored for symptom expression on symptom expression, and RT-PCR. The jade vine and Jack bean plants were infected by SMV, showingdeveloped mild mosaic symptoms approximately 60 and 15 days after inoculation, respectively , whereas the plants of other species were absent of any visible symptoms . To confirm the potyvirus identity, the jade vine samples were also tested by cConventional RT-PCR with SMV-specific primers pairs CP-F-SMV/CP-R-SMV (Jaramillo Mesa et al., 2018) and SMV-CPf/SMV-CPr (Wang and Ghabrial, 2002), thawhicht amplify fragments of 1000 990-bp and 469-bp90, respectively, nucleotides offrom the CP geneome region of SMV was performed, respectively. Amplicons of expected sizes were obtained from the total RNA of the leaves of field-infected and the mechanically inoculated plant of jade plantsvine as well as the Jack bean plants, but not from the asymptomatic jade plantvine and plants of other species the negative control. The viral nucleotide sequences obtained with the above pairs of primersBLASTn analysis of nucleotide sequences of the amplicons showed that they share 96.81% and 97.63% identity, respectively, with the same Korean SMV isolate WS162. These results demonstrate that… the field-symptomatic jade vine was infected with SMV, which is naturally transmitted by aphids speciess in a non-persistent manner and via soybean infected seeds (Hajimorad et al. 2018)( ). The virus appears to have has a restricted narrow natural host range., Aapart from soybean, and to date, it has only been reported the natural infection has been documented only in soybean, Lagenaria siceraria, Passiflora spp., Pinellia ternata, Senna occidentalis, and Vigna angularis (Almeida et al., 2002; Chakraborty et al. 2016; Hajimorad et al. 2018). To our knowledge, this is the first report of SMV in S. macrobotrys in the world. Further surveys are necessary to determine the incidence of the virus in ornamental jade plants vines and its importance as virus reservoirs for commercial soybean crops.

First report of groundnut ringspot virus infecting Zinnia sp. in Brazil.

Zinnia sp. is a genus belonging to Asteraceae family, originated in Mexico and adapted to a warm-hot climate (Hemmati and Mehrnoosh, 2017). Several types of zinnias with different flower color and forms are cultivated in Brazil (Min et al., 2020 and Souza Jr. et al., 2020). Characteristic symptoms of infection caused by orthotospovirus, including chlorotic spots and concentric rings on the leaves, were observed in two plants of Zinnia sp. of a florist located in the city of Piracicaba, State of São Paulo, Brazil. Orthotospovirus-like particles were observed by transmission electron microscope in leaf extracts from both plants, stained negatively with 1% uranyl acetate. By analyzing ultrathin sections of infected leaf tissues, particles of 80-100 nm in diameter were found in the lumen of the endoplasmic reticulum and nucleocapsid aggregates in the cytoplasm. Total RNA extracted separately from the leaves of both samples, using the Purelink Viral DNA / RNA kit (Thermo Fisher Scientific), was used to detect the virus by reverse transcription polymerase chain reaction (RT-PCR), using the universal primers for orthotospovirus BR60, complementary to the 3' end of the non-translated region of the S RNA (position 1 to 15 nt), and BR65, matching the nucleocapsid gene (N) (position 433 to 453 nt), generating and amplicon of 453 nt (Eiras et al., 2001). Amplicons of the expected size were obtained for the two samples. An amplicon was purified with the Wizard SV Gel and PCR Clean-Up System kit (Promega) and sequenced in both directions at Macrogen Inc (South Korea). The nucleotide sequence (GenBank MW629018) showed 99.29-99.76% identity with nucleotide sequences of the orthotospovirus groundnut ringspot virus (GRSV) isolates (GenBank MH686229 and KY400110). Leaf extracts from symptomatic plants were also analyzed by plate-trapped antigen-enzyme-linked immunosorbent assay (PTA-ELISA), using polyclonal antiserum produced against the GRSV nucleocapsid protein (Esquivel et al., 2019). The absorbance values obtained for the extracts of the two symptomatic plants of Zinnia sp. (1.3 and 1.7) were twice as high as the value obtained for the healthy plant extract (0.5). Leaf extract of symptomatic Zinnia sp. was inoculated mechanically onto leaves of healthy plants of Zinnia sp., Capsicum annuum cv. Dara, Cucumis sativus, Cucurbita pepo cv. Caserta, Chenopodium amaranticolor, Datura stramonium, Nicotiana tabacum cv. Turkish and Solanum lycopersicum cv. Compack. At 5 days post inoculation (dpi), inoculated leaves of D. stramonium reacted with local lesions, and at 9 dpi, newly developed leaves of inoculated S. lycopersicum plants showed necrotic spot and concentric ring symptoms, whereas C. annuum exhibited concentric rings at 10 dpi. Inoculated zinnia plants showed systemic chlorotic spot and concentric ring symptoms at 20 dpi, indistinguishable from those observed under natural infection. The other inoculated plant species were not symptomatic, nor the virus was detected. PTA-ELISA and RT-PCR confirmed infection with GRSV in symptomatic plants. The amplicons generated by RT-PCR of total RNA extracted from an experimentally infected plant of C. annuum and D. stramonium, and two plants of Zinnia sp. were sent for nucleotide sequencing. The obtained nucleotide sequences (MW629019, MW629020, MW629021, MW629022) shares 100% identity with the nucleotide sequence corresponding to the original GRSV isolate (MW629018) identified in Zinnia sp. This is the first report of the natural occurrence of GRSV in Zinnia sp. in Brazil. Studies on incidence and damage are needed to recommend alternatives for management.

First report of costus stripe mosaic virus infecting Tradescantia spathacea plants in Brazil.

Tradescantia spathacea (family Commelinaceae) is cultivated worldwide as an ornamental (Golczyk et al., 2013) and as medicinal plant (Tan et al., 2020). In 2019, 90 of ~180 plants of T. spathacea, grown in two beds of 4 m2 and exhibiting leaf mosaic were found in an experimental area at ESALQ/USP (Piracicaba municipality, São Paulo state, Brazil). Potyvirus-like flexuous filamentous particles were observed by transmission electron microscopy in foliar extracts of two symptomatic plants stained with 1% uranyl acetate. Total RNA was extracted using the Purelink viral RNA/DNA kit (Thermo Fisher Scientific) from leaves of two symptomatic plants and separately subjected to a reverse transcription polymerase chain reaction (RT-PCR). The potyviruses degenerate pairs of primers CIFor/CIRev (Ha et al. 2008), which amplifies a fragment corresponding to part of the cylindrical inclusion protein gene, and WCIEN/PV1 (Maciel et al. 2011), which amplifies a fragment containing part of the capsid protein gene and the 3' untranslated region, were used. The expected amplicons (~700bp) were obtained from both total RNA extracts. Two amplicons from one sample were purified using the Wizard SV Gel and PCR Clean-Up System kit (Promega) and directly sequenced in both directions at Macrogen Inc (Seoul, South Korea). The obtained nucleotide sequences (GenBank MW430005 and MW503934) shared 95.32% and 97.79% nucleotide identity, respectively, with the corresponding sequences of the Brazilian isolate of the potyvirus costus stripe mosaic virus (CoSMV, MK286375) (Alexandre et al. 2020). Extract from an infected plant of T. spathacea was mechanically inoculated in 10 healthy plants of T. spathacea and two plants each of the following species: Capsicum annuum, Chenopodium amaranticolor, Commelina benghalensis, Datura stramonium, Gomphrena globosa, Nicandra physaloides, Nicotiana tabacum cvs. Turkish and Samsun, Solanum lycopersicum, T. palida, and T. zebrina. All T. spathacea plants exhibited mosaic and severe leaf malformation. C. benghalensis plants developed mild mosaic, whereas infected T. zebrina plants were asymptomatic. The plants of other species were not infected. RT-PCR with specific CoSMV primers CoSMVHC-F and CoSMVHC-R (Alexandre et al. 2020) confirmed the infection. Nucleotide sequences of amplicons obtained from experimentally inoculated T. spathacea and T. zebrina (MW430007 and MW430008) shared 94.56% and 94.94% identity with the corresponding sequence of a Brazilian CoSMV isolate (MK286375). None of eight virus-free plants of T. spathacea inoculated with CoSMV using Aphis craccivora exhibited symptoms, nor was CoSMV detected by RT-PCR. Lack of CoSMV transmission by A. solanella, Myzus persicae, and Uroleucon sonchi was previously reported (Alexandre et al. 2020). T. spathacea plants are commonly propagated vegetatively, and by seeds. Virus-free seeds, if available, can provide an efficient and easy way to obtain healthy plants. Only three viruses were reported in plants of the genus Tradescantia: Commelina mosaic virus, tradescantia mild mosaic virus, and a not fully characterized potyvirus (Baker and Zettler, 1988; Ciuffo et al., 2006; Kitajima 2020). CoSMV was recently reported infecting Costus spiralis and C. comosus (Alexandre et al. 2020). As far as we know, this is the first report of CoSMV infecting T. spathacea plants.

Near-complete genome sequence and biological properties of an allexivirus found in Senna rizzinii in Brazil.

Senna rizzinii is a flowering shrub found mainly in the northeast region of Brazil. Here, we report the coding-complete genome sequence, particle morphology, mode of transmission, and the indicator host responses of an isolate of the putative allexivirus cassia mild mosaic virus (CaMMV) found in S. rizzinii. The virus was transmitted mechanically to Chenopodium amaranticolor, C. quinoa, Gomphrena globosa, which showed local lesions, and S. rizzinii, and S. occidentalis, which were infected systemically. It was also efficiently transmitted to S. rizzinii by grafting. Seed transmission was not observed. The near-complete genome sequence of the virus is 7829 nucleotides in length, containing six open reading frames (ORF), like other allexiviruses.

First Report of Cichorium endivia (Asteraceae) as a Natural Host of Groundnut ringspot orthotospovirus in Brazil.

Endive (Cichorium endivia L.) is a very important cash crop for small farmers in Brazil. During inspections conducted in the summer season of 2019-2020, leaf samples of C. endivia 'La Spezia' seedlings exhibiting typical symptoms of orthotospoviruses infection (viz. concentric chlorotic spots and apical leaf deformation; ≈ 10%) were collected in commercial greenhouses in Brasília-DF, Central Brazil. Leaves of one healthy and three symptomatic plants were initially evaluated via double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with polyclonal antibodies (produced at CNPH) raised against the nucleoprotein of the three major orthotospoviruses: tomato spotted wilt orthotospovirus (TSWV), groundnut ringspot orthotospovirus (GRSV) and tomato chlorotic spot orthotospovirus (TCSV). Strong serological reactions were observed only against GRSV antibodies exclusively in extracts from symptomatic samples. In order to confirm the causal agent of those symptoms, total RNA was extracted (Trizol®; Sigma) from infected leaf samples and used in a two-step reverse transcriptase polymerase chain reaction (RT-PCR) approach. Synthesis of the cDNA was carried out with the J13 primer (5'-CCC GGA TCC AGA GCA AT-3') (Cortez et al., 2001) followed by PCR assays with the primer pair BR60 (5'-AGA GCA ATC GTG TCA-3`) and BR65 (5'-ATC AAG CCT TCT GAA AGT CAT-3') (Eiras et al., 2001). This primer set amplifies a fragment of 453 bp including the untranslated region at the 3' terminus of the small RNA and the protein N-coding gene of at least five orthotospoviruses: TSWV, GRSV, TCSV, chrysanthemum stem necrosis orthotospovirus (CSNV) and zucchini lethal chlorosis orthotospovirus (ZLCV) (Eiras et al., 2001). The obtained amplicons (≈ 432 bp) were subsequently subjected to Sanger dideoxy nucleotide sequencing at CNPH. BLASTn analysis showed >99% identity with a wide array of GRSV isolates available in the GenBank. The nucleotide sequence of Tospo #1 (MT215222) and Tospo #3 (MT215224) isolates displayed 100% identity between them, whereas the Tospo #2 (MT215223) isolate displayed one non-synonymous point mutation in the 3' untranslated region in comparison with the former two isolates. Three plants of C. endivia, Capsicum annuum L. cv. Ikeda, tomato (Solanum lycopersicum L.) cv. Santa Clara and its isoline 'LAM-147' (with the Sw-5 resistance gene), Nicotiana rustica L., Lactuca sativa L. ('Vanda' and 'PI-342444') and Gomphrena globosa L. were mechanically inoculated individually with each GRSV isolate in order to confirm their pathogenicity. Chlorotic lesions and mosaic were observed seven days after inoculation of all plant materials, except the tomato inbred line 'LAM-147', which has the Sw-5 gene that confers broad-spectrum resistance to all Brazilian orthotospoviruses (Boiteux and Giordano, 1993). The GRSV infection was confirmed via DAS-ELISA and RT-PCR 15 days after inoculation, using the same set of antibodies and the primer pair BR60 / BR65. Transmission electron microscopy of ultrathin sections from symptomatic leaf tissues, both from field-infected and experimentally inoculated endive revealed the presence of typical orthotospovirus particles, within endoplasmic reticulum cisternae. Natural infection of endive by TSWV has been reported in Greece (Chatzivassiliou et al., 2000) and by TCSV in São Paulo State, Brazil and in Florida, USA (Subramanya Sastry et al., 2019). To our knowledge, it is the first report of GRSV naturally infecting this Asteraceae species in Brazil. Confirmation of GRSV infection of C. endivia plants is a relevant piece of information aiming to design effective disease management strategies. References: Boiteux, L.S. and Giordano, L. B. 1993. Euphytica 71: 151. Eiras, M. et al. 2001. Fitopatol. Bras. 26: 170. Chatzivassiliou, E.K. et al. 2000 Ann. Appl. Biol. 137: 127. Cortez, I., et al. 2001. Arch. Virol. 146: 265. Subramanya Sastry, K., et al. 2019. Encyclopedia of plant viruses and viroids. Springer, New Delhi. https://doi.org/10.1007/978-81-322-3912-3.

First report of bidens mosaic virus infecting Centella asiatica in Brazil.

Centella asiatica is a perennial, herbaceous creeper plant that belongs to the family Apiaceae. It has been known since prehistoric times and has been used for therapeutic and cosmetic purposes (James and Dubery 2009; Gohil et al. 2010), and is easily propagated vegetatively. In 2018, plants of C. asiatica exhibiting foliar symptoms of mosaic and malformation were found in the botanical garden of the Plantarum Institute (Nova Odessa municipality, São Paulo state - 22°46'45.8"S 47°18'47.5"W) and in an experimental area at ESALQ/USP (Piracicaba municipality, São Paulo state - 22°42'26.0"S 47°37'48.6"W). In both locations the plants were grown in beds of approximately 4 m2 and all of them were symptomatic. Initially, leaf extract from symptomatic C. asiatica plants was examined by transmission electron microscopy (TEM) after being negatively stained with 1% uranyl acetate. Potyvirus-like flexuous filamentous particles were observed in leaf samples from both locations. TEM of thin sections of symptomatic leaf tissues revealed the presence of cylindrical inclusions, characteristic of infection by potyviruses, in the cytoplasm of epidermal, parenchymal, and vascular cells. Total RNA was extracted from symptomatic leaves collected in the Plantarum Institute (3 samples), and at Escola Superior de Agricultura Luiz de Queiroz (1 sample) using the Purelink viral RNA/DNA kit (Thermo Fisher Scientific, Waltham, USA). Reverse Transcription -Polymerase Chain Reaction (RT-PCR) was performed using the degenerate primers CIFor (5'-GGIVVIGTIGGIWSIGGIAARTCIAC-3') and CIRev (5'-ACICCRTTYTCDATDATRTTIGTIGC-3'), which amplify a fragment of approximately 700 bp within the the cylindrical inclusion protein gene of potyviruses (Ha et al. 2008). Amplicons of the expected size were obtained for all four samples analysed. One amplicon per location was purified using the Wizard® SV Gel and PCR Clean-Up System kit (Promega), and directly sequenced in both directions at Macrogen Inc (Seoul, South Korea). The nucleotide sequences obtained from the symptomatic C. asiatica plants collected in the Plantarum Institute (GenBank Acc. No. MT668627), and at ESALQ/USP (GenBank Acc. No. MT668626) showed 97.1% and 96.2% identity, respectively, with the nucleotide sequence of a Brazilian isolate of bidens mosaic virus (BiMV), family Potyviridae, genus Potyvirus (GenBank Acc. No. KF649336). To confirm the infection of C. asiatica plants with BiMV, the previously extracted RNAs were analyzed by RT-PCR using the specific primers 8331 (5'-CGTGGGGCTATCCTGAATTG-3') and 9046 (5'-CCACATCAGAGAAGTGTGCC-3'), which amplify a fragment of 715 bp corresponding to the BiMV coat protein gene (Suzuki et al. 2009). The expected size amplicons were obtained for all four samples of symptomatic plants of C. asiatica. The nucleotide sequences of two amplicons (GenBank Acc. Nos. MT668628, and MT668629), representing plants from each location, showed 94.6% to 95.6% identities with corresponding nucleotide sequences of the coat protein gene of BiMV from Brazil (GenBank Acc. Nos. KF649336, AY960150, and AY960151). A leaf extract of a symptomatic C. asiatica plant was mechanically inoculated to healthy plants of Apium graveolens, Bidens pilosa, C. asiatica, Chenopodium amaranticolor, C. quinoa, Coriander sativum, Nicotiana benthamiana, N. tabacum and Petroselinum crispum. C. asiatica became systemically infected, reproducing the original symptoms of leaf mosaic and malformation. N. benthamiana was infected and developed severe mosaic symptoms, whereas C. amaranticolor and C. quinoa reacted only with necrotic and chlorotic local lesions, respectively. Other assayed plants were not infected. Potyvirus-like particles were observed by TEM in the infected plants and BiMV infection was confirmed by RT-PCR. Transmission assays of the BiMV isolate by aphids Myzus persicae and Aphys gossypii to healthy C. asiatica plants were also performed. Virus-free aphids of the two species, reared on Capsicum annuum and Gossypium hirsutum respectively, were fasted for 30 min and then placed, separately, on symptomatic leaves of C. asiatica for an acquisition access period (AAP) of 10 min. After that, groups of six insects were transferred, separately, to four healthy C. asiatica plants for an inoculation access period (IAP) of 24 h. After inoculation the insects were killed manually. Approximately 30 days later, one plant inoculated with each species of aphid exhibited symptoms and infection was confirmed by RT-PCR and nucleotide sequencing of the amplicons. BiMV was absent in control, non-inoculated plants in both mechacial and aphid transmission assays. Infection of spontaneously growing C. asiatica plants by potyvirus, determined by TEM, was previously reported in Curitiba and Colombo, state of Paraná, Brazil by Lima Neto and Souza (1981), but the virus was not fully characterized and identified. In addition to BiMV, plants of C. asiatica are also suscptible to infection with cucumber mosaic virus (CMV), as reported by Cardin and Moury (2010) in Madagascar. This is the first identification of BiMV naturally infecting C. asiatica. Additional works on effects of BiMV infection of C. asiatica on commercial production and pharmaceutical properties are required.

On some morphological and ultrastructural features of the insemination system in five species of the genus Brevipalpus (Acari: Tenuipalpidae).

The genus Brevipalpus (Tenuipalpidae) includes 291 described species commonly found in the tropical and subtropical regions. Morphological characters considered in the taxonomy of Brevipalpus species are difficult to discern, which often leads to erroneous identifications and the presence of cryptic species within species is suspected. New morphological characters are now considered relevant for identification of Brevipalpus species; among them, the morphology of the seminal receptacle (spermatheca) of the female insemination system. This feature has not been considered relevant until now; thus, there is little information about the insemination system in the available species descriptions. Hence, in the present study, ultrastructural details are provided for the insemination system in five species of Brevipalpus, representing different morphological groups. The seminal receptacle (spermatheca) and the insemination duct are illustrated using light, transmission and scanning electron microscopy. The spermatheca proved to have specific morphological features that can be useful for taxonomic purposes. On the other hand, its appearance within a population might be variable in a way that needs to be ascertained and evaluated.

Characterization of a bacteriophage with broad host range against strains of Pseudomonas aeruginosa isolated from domestic animals.

BACKGROUND: Pseudomonas aeruginosa is an opportunistic pathogen and one of the leading causes of nosocomial infections. Moreover, the species can cause severe infections in cystic fibrosis patients, in burnt victims and cause disease in domestic animals. The control of these infections is often difficult due to its vast repertoire of mechanisms for antibiotic resistance. Phage therapy investigation with P. aeruginosa bacteriophages has aimed mainly the control of human diseases. In the present work, we have isolated and characterized a new bacteriophage, named Pseudomonas phage BrSP1, and investigated its host range against 36 P. aeruginosa strains isolated from diseased animals and against P. aeruginosa ATCC strain 27853. RESULTS: We have isolated a Pseudomonas aeruginosa phage from sewage. We named this virus Pseudomonas phage BrSP1. Our electron microscopy analysis showed that phage BrSP1 had a long tail structure found in members of the order Caudovirales. "In vitro" biological assays demonstrated that phage BrSP1 was capable of maintaining the P. aeruginosa population at low levels for up to 12 h post-infection. However, bacterial growth resumed afterward and reached levels similar to non-treated samples at 24 h post-infection. Host range analysis showed that 51.4% of the bacterial strains investigated were susceptible to phage BrSP1 and efficiency of plating (EOP) investigation indicated that EOP values in the strains tested varied from 0.02 to 1.72. Analysis of the phage genome revealed that it was a double-stranded DNA virus with 66,189 bp, highly similar to the genomes of members of the genus Pbunavirus, a group of viruses also known as PB1-like viruses. CONCLUSION: The results of our "in vitro" bioassays and of our host range analysis suggested that Pseudomonas phage BrSP1 could be included in a phage cocktail to treat veterinary infections. Our EOP investigation confirmed that EOP values differ considerably among different bacterial strains. Comparisons of complete genome sequences indicated that phage BrSP1 is a novel species of the genus Pbunavirus. The complete genome of phage BrSP1 provides additional data that may help the broader understanding of pbunaviruses genome evolution.

Molecular and biological characterization of a putative new sobemovirus infecting Physalis peruviana.

Physalis peruviana is a perennial solanaceous plant that has recently been established as a commercial crop in Brazil. This work reports the near-complete genome sequence, particle morphology, and plant host responses to a putative new sobemovirus, named "physalis rugose mosaic virus". The virus, characterized by isometric particles of ca. 30 nm in diameter, causes foliar symptoms of mosaic, malformation and blistering, accompanied by stunting. The near-complete genome sequence comprises 4175 nucleotides and contains five open reading frames that are similar to those of other sobemoviruses. In addition to P. peruviana, the new virus systemically infected Capsicum annuum, Nicotiana tabacum and Solanum lycopersicum by mechanical inoculation. Thus, this virus may cause disease in these crops in the field.

Biological and molecular characterization of a putative new potexvirus infecting Senna occidentalis.

In this work, we report the complete genome sequence of, production of polyclonal antibodies against, and development of biological assays for a putative new potexvirus, named senna mosaic virus (SenMV), found infecting Senna occidentalis in the state of São Paulo, Brazil. The complete genome sequence of SenMV comprises 6775 nucleotides excluding the poly(A) tail. The genome organization is similar to those of other potexviruses, with five open reading frames coding for RNA-dependent RNA polymerase (RdRp), the triple gene block (TGB 1, 2, and 3) proteins, and coat protein (CP). The virus was transmitted to S. occidentalis by mechanical inoculation and trimming scissors, but not by seeds.

Virus-vector relationship in the Citrus leprosis pathosystem.

Citrus leprosis has been one of the most destructive diseases of citrus in the Americas. In the last decade important progress has been achieved such as the complete genome sequencing of its main causal agent, Citrus leprosis virus C (CiLV-C), belonging to a new genus Cilevirus. It is transmitted by Brevipalpus yothersi Baker (Acari: Tenuipalpidae), and is characterized by the localized symptoms it induces on the leaves, fruits and stems. It occurs in the American continents from Mexico to Argentina. The virus was until recently considered restricted to Citrus spp. However, it was found naturally infecting other plants species as Swinglea glutinosa Merrill and Commelina benghalensis L., and has been experimentally transmitted by B. yothersi to a large number of plant species. Despite these advances little is known about the virus-vector relationship that is a key to understanding the epidemiology of the disease. Some components of the CiLV-C/B. yothersi relationship were determined using the common bean (Phaseolus vulgaris L. cv. 'IAC Una') as a test plant. They included: (a) the virus acquisition access period was 4 h; (b) the virus inoculation access period was 2 h; (c) the latent period between acquisition and inoculation was 7 h; (d) the period of retention of the virus by a single viruliferous mite was at least 12 days; (d) the percentage of viruliferous individuals from mite colonies on infected tissues ranged from 25 to 60%. The experiments confirmed previous data that all developmental stages of B. yothersi (larva, protonymph and deutonymph, adult female and male) were able to transmit CiLV-C and that transovarial transmission of the virus did not occur. CiLV-C can be acquired from lesions on leaves, fruits and stems by B. yothersi. Based on the distribution of lesions produced by single viruliferous B. yothersi on bean leaves, it is concluded that they tend to feed in restricted areas, usually near the veins. The short latent and transmission periods during the larval stage suggest that the CiLV-C/B. yothersi relationship is of the persistent circulative type.

A betabaculovirus encoding a gp64 homolog.

BACKGROUND: A betabaculovirus (DisaGV) was isolated from Diatraea saccharalis (Lepidoptera: Crambidae), one of the most important insect pests of the sugarcane and other monocot cultures in Brazil. RESULTS: The complete genome sequence of DisaGV was determined using the 454-pyrosequencing method. The genome was 98,392 bp long, which makes it the smallest lepidopteran-infecting baculovirus sequenced to date. It had a G + C content of 29.7% encoding 125 putative open reading frames (ORF). All the 37 baculovirus core genes and a set of 19 betabaculovirus-specific genes were found. A group of 13 putative genes was not found in any other baculovirus genome sequenced so far. A phylogenetic analysis indicated that DisaGV is a member of Betabaculovirus genus and that it is a sister group to a cluster formed by ChocGV, ErelGV, PiraGV isolates, ClanGV, CaLGV, CpGV, CrleGV, AdorGV, PhopGV and EpapGV. Surprisingly, we found in the DisaGV genome a G protein-coupled receptor related to lepidopteran and other insect virus genes and a gp64 homolog, which is likely a product of horizontal gene transfer from Group 1 alphabaculoviruses. CONCLUSION: DisaGV represents a distinct lineage of the genus Betabaculovirus. It is closely related to the CpGV-related group and presents the smallest genome in size so far. Remarkably, we found a homolog of gp64, which was reported solely in group 1 alphabaculovirus genomes so far.

Taxonomy of the order Mononegavirales: update 2016.

In 2016, the order Mononegavirales was emended through the addition of two new families (Mymonaviridae and Sunviridae), the elevation of the paramyxoviral subfamily Pneumovirinae to family status (Pneumoviridae), the addition of five free-floating genera (Anphevirus, Arlivirus, Chengtivirus, Crustavirus, and Wastrivirus), and several other changes at the genus and species levels. This article presents the updated taxonomy of the order Mononegavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).

A highly divergent isolate of tomato blistering mosaic virus from Solanum violaefolium.

The complete genome of a tymovirus infecting Solanum violaefolium was sequenced. The genome comprised 6284 nt, with a 5'-UTR of 137 nt and a comparatively longer 3'-UTR of 121 nt. Sequence analysis confirmed three ORFs encoding a movement protein, a polyprotein, and a coat protein (CP). The isolate was considered to be the Tomato blistering mosaic virus (ToBMV) based on a CP amino acid sequence identity of 95.3 %. The nucleotide sequence of the complete genome of the S. violaefolium isolate, however, differed markedly from the other two reported ToBMV isolates, with identities of 76.6 and 76.3 %, below one of the demarcation criteria of the genus Tymovirus (overall genome identity of 80 %). No recombination signals were detected in the genome of this isolate. The high identity of the CP amino acid sequence and similar host responses suggest that the S. violaefolium isolate belongs to the same species as the Tomato blistering mosaic virus. The sequence analysis of this ToBMV isolate thus suggests that the demarcation criterion of 80 % overall genome sequence identity in the genus Tymovirus may require revision.

Association of 'Candidatus Liberibacter solanacearum' with a vegetative disorder of celery in Spain and development of a real-time PCR method for its detection.

A new symptomatology was observed in celery (Apium graveolens) in Villena, Spain in 2008. Symptomatology included an abnormal amount of shoots per plant and curled stems. These vegetative disorders were associated with 'Candidatus Liberibacter solanacearum' and not with phytoplasmas. Samples from plant sap were immobilized on membranes based on the spot procedure and tested using a newly developed real-time polymerase chain reaction assay to detect 'Ca. L. solanacearum'. Then, a test kit was developed and validated by intralaboratory assays with an accuracy of 100%. Bacterial-like cells with typical morphology of 'Ca. Liberibacter' were observed using electron microscopy in celery plant tissues. A fifth haplotype of 'Ca. L. solanacearum', named E, was identified in celery and in carrot after analyzing partial sequences of 16S and 50S ribosomal RNA genes. From our results, celery (family Apiaceae) can be listed as a new natural host of this emerging bacterium.

A cilevirus infects ornamental hibiscus in Hawaii.

The complete nucleotide sequence of a virus infecting ornamental hibiscus (Hibiscus sp.) in Hawaii with symptoms of green ringspots on senescing leaves was determined from double-stranded RNA isolated from symptomatic tissue. Excluding polyadenylated regions at the 3' termini, the bipartite RNA genome was 8748 and 5019 nt in length for RNA1 and RNA2, respectively. The genome organization was typical of a cilevirus: RNA1 encoded a large replication-associated protein with methyltransferase, protease, helicase and RNA-dependent RNA polymerase domains as well as a 29-kDa protein of unknown function. RNA2 possessed five open reading frames that potentially encoded proteins with molecular masses of 15, 7, 62, 32, and 24 kDa. The 32-kDa protein is homologous to 3A movement proteins of RNA viruses; the other proteins are of unknown function. A proteome comparison revealed that this virus was 92 % identical to citrus leprosis virus cytoplasmic type 2 (CiLV-C2), a recently characterized cilevirus infecting citrus with leprosis-like symptoms in Colombia. The high sequence similarity suggests that the virus described in this study could be a strain of CiLV-C2, but since the new genus Cilevirus does not have species demarcation criteria established at present, the classification of this virus infecting hibiscus is open to interpretation. This study represents the first documented case of a cilevirus established in the United States and provides insight into the diversity within the genus Cilevirus.

A Capsid Protein Fragment of a Fusagra-like Virus Found in Carica papaya Latex Interacts with the 50S Ribosomal Protein L17.

Papaya sticky disease is caused by the association of a fusagra-like and an umbra-like virus, named papaya meleira virus (PMeV) and papaya meleira virus 2 (PMeV2), respectively. Both viral genomes are encapsidated in particles formed by the PMeV ORF1 product, which has the potential to encode a protein with 1563 amino acids (aa). However, the structural components of the viral capsid are unknown. To characterize the structural proteins of PMeV and PMeV2, virions were purified from Carica papaya latex. SDS-PAGE analysis of purified virus revealed two major proteins of ~40 kDa and ~55 kDa. Amino-terminal sequencing of the ~55 kDa protein and LC-MS/MS of purified virions indicated that this protein starts at aa 263 of the deduced ORF1 product as a result of either degradation or proteolytic processing. A yeast two-hybrid assay was used to identify Arabidopsis proteins interacting with two PMeV ORF1 product fragments (aa 321-670 and 961-1200). The 50S ribosomal protein L17 (AtRPL17) was identified as potentially associated with modulated translation-related proteins. In plant cells, AtRPL17 co-localized and interacted with the PMeV ORF1 fragments. These findings support the hypothesis that the interaction between PMeV/PMeV2 structural proteins and RPL17 is important for virus-host interactions.

'Candidatus Phytoplasma sudamericanum', a novel taxon, and strain PassWB-Br4, a new subgroup 16SrIII-V phytoplasma, from diseased passion fruit (Passiflora edulis f. flavicarpa Deg.).

Symptoms of abnormal proliferation of shoots resulting in formation of witches'-broom growths were observed on diseased plants of passion fruit (Passiflora edulis f. flavicarpa Deg.) in Brazil. RFLP analysis of 16S rRNA gene sequences amplified in PCRs containing template DNAs extracted from diseased plants collected in Bonito (Pernambuco) and Viçosa (Minas Gerais) Brazil, indicated that such symptoms were associated with infections by two mutually distinct phytoplasmas. One phytoplasma, PassWB-Br4 from Bonito, represents a new subgroup, 16SrIII-V, in the X-disease phytoplasma group ('Candidatus Phytoplasma pruni'-related strains). The second phytoplasma, PassWB-Br3 from Viçosa, represents a previously undescribed subgroup in group 16SrVI. Phylogenetic analyses of 16S rRNA gene sequences were consistent with the hypothesis that strain PassWB-Br3 is distinct from previously described 'Ca. Phytoplasma' species. Nucleotide sequence alignments revealed that strain PassWB-Br3 shared less than 97.5 % 16S rRNA gene sequence similarity with previously described 'Ca. Phytoplasma' species. The unique properties of its DNA, in addition to natural host and geographical occurrence, support the recognition of strain PassWB-Br3 as a representative of a novel taxon, 'Candidatus Phytoplasma sudamericanum'.

From Contagium vivum fluidum to Riboviria: A Tobacco Mosaic Virus-Centric History of Virus Taxonomy.

Viruses were discovered as agents of disease in the late 19th century, but it was not until the 1930s that the nature of these agents was elucidated. Nevertheless, as soon as viral diseases started to be recognized and cataloged, there were attempts to classify and name viruses. Although these early attempts failed to be adopted by the nascent virology community, they are evidence of the human compulsion to try to organize the natural world into well-defined categories. Different classification schemes were proposed during the 20th century, but again none were widely embraced by virologists. In 1966, with the creation of the International Committee on Nomenclature of Viruses (eventually renamed as the International Committee on Taxonomy of Viruses), a more organized effort led to an official taxonomy in which viruses were classified into families and genera. At present, a much better understanding of the evolutionary relationships among viruses has led to the establishment of a 15-rank taxonomy based primarily on these evolutionary relationships. This review of virus taxonomy will be centered on the tobacco mosaic virus (TMV), the agent of the disease studied by Dmitry Ivanovsky and the first virus to be recognized as such, which was often historically at the center of major advancements in virology during the 20th century.