Cost-effectiveness Analysis of Pharmacological Treatment for Adult Kidney Transplant Recipients in Colombia.

OBJECTIVES: To evaluate cost-effective pharmacological treatment in adult kidney transplant recipients from the perspective of the Colombian health system. METHODS: A decision tree model for the induction phase and a Markov model for the maintenance phase were built. A review of the clinical literature was conducted to extract probabilities, and the life-years were used as the outcome. Costs were calculated using the administrative databases. The evaluating treatment schemes are organized by groups of evidence with direct comparisons. RESULTS: In the induction phase, anti-thymocyte immunoglobulin+ methylprednisolone is dominant, more effective, and less expensive, compared with basiliximab+methylprednisolone. In the maintenance phase, azathioprine (AZA) is dominant in contrast to mycophenolate mofetil (MFM) both with cyclosporine (CIC)+ corticosteroids (CE); CIC is dominant relative to sirolimus (SIR) and tacrolimus (TAC) (both with MFM+CE or AZA+CE), and TAC is dominant compared with SIR (in addition with MFM+CE or mycophenolate sodium [MFS]+CE); MFM is dominant in relation to MFS and everolimus, and SIR is more effective MFM but it does not exceed the threshold (in sum with TAC+CE); MFS and MFM are dominant relative to everolimus, and SIR is more effective than MFM, but it does not exceed the threshold (in addiction with CIC+CE); MFM is dominant in relation to TAC (in sum with SIR+CE), and CIC+AZA+CE is dominant in relation to TAC+MFM+CE. CONCLUSIONS: The base-case results for all evidence groups are consistent with the different sensitivity analyses.

Occurrence, Distribution, and Population Structure of Schlumbergera Virus X in Dragon Fruit in Ecuador.

The occurrence of Schlumbergera virus X (SchVX) in commercial dragon fruit fields in three provinces of Ecuador has been identified in this study. The virus was found in symptomatic and asymptomatic cladodes of the two major species (Hylocereus undatus and H. megalanthus) cultivated in the country. Symptoms in H. undatus included irregular and ring-shaped chlorotic spots that coalesce into large chlorotic patches along the cladodes, whereas small chlorotic spot symptoms on the cladodes were observed in H. megalanthus. Phylogenetic inferences based on 27 partial nucleotide sequences of the RNA-dependent RNA polymerase (RdRp) and three whole genome comparisons showed that Ecuadorean isolates from H. undatus and H. megalanthus share a most recent ancestor with isolates from Spain and Portugal. In addition, an SchVX isolate with a distinct genomic lineage was found in symptomatic H. polyrhizus plants from a single location, suggesting two independent virus introductions into the country.

Inhibition of PRL2 Upregulates PTEN and Attenuates Tumor Growth in Tp53-deficient Sarcoma and Lymphoma Mouse Models.

The phosphatases of regenerating liver (PRL) are oncogenic when overexpressed. We previously found that PRL2 deletion increases PTEN, decreases Akt activity, and suppresses tumor development in a partial Pten-deficient mouse model. The current study aims to further establish the mechanism of PTEN regulation by PRL2 and expand the therapeutic potential for PTEN augmentation mediated by PRL2 inhibition in cancers initiated without PTEN alteration. The TP53 gene is the most mutated tumor suppressor in human cancers, and heterozygous or complete deletion of Tp53 in mice leads to the development of sarcomas and thymic lymphomas, respectively. There remains a lack of adequate therapies for the treatment of cancers driven by Tp53 deficiency or mutations. We show that Prl2 deletion leads to PTEN elevation and attenuation of Akt signaling in sarcomas and lymphomas developed in Tp53 deficiency mouse models. This results in increased survival and reduced tumor incidence because of impaired tumor cell proliferation. In addition, inhibition of PRL2 with a small-molecule inhibitor phenocopies the effect of genetic deletion of Prl2 and reduces Tp53 deficiency-induced tumor growth. Taken together, the results further establish PRL2 as a negative regulator of PTEN and highlight the potential of PRL2 inhibition for PTEN augmentation therapy in cancers with wild-type PTEN expression. SIGNIFICANCE: Prl2 deletion attenuates Tp53 deficiency-induced tumor growth by increasing PTEN and reducing Akt activity. Targeting Tp53-null lymphoma with PRL inhibitors lead to reduced tumor burden, providing a therapeutic approach via PTEN augmentation.

Cost-Effectiveness of Tacrolimus Compared With Cyclosporine for Immunosuppression Therapy in Patients Who Underwent Heart Transplant in Colombia.

OBJECTIVES: To evaluate the cost-effectiveness of pharmacological treatment in maintenance therapy for adult heart transplant recipients from the Colombian health system perspective. METHODS: We constructed a decision tree model with a 1-year time horizon. A review of the clinical literature was performed to extract probabilities of health events and acute rejections avoided were used as the health outcome. Costs were calculated from the base-case approximation and were obtained from administrative databases in Colombia (Sistema de Información de Precios de Medicamentos 2020 and Suficiencia 2012-2019), and the prices were adjusted to US dollar 2021. RESULTS: Two evaluation results were presented. The first evaluates the tacrolimus + azathioprine + corticosteroid (TAC) scheme compared with cyclosporine + azathioprine + corticosteroid (CAC), in which the incremental cost-effectiveness ratio indicates that 1 additional rejection avoided has a cost of US dollar $5461.09 which, compared with the cost-effectiveness threshold in the base case, indicates that the TAC scheme is not a cost-effective (CE) strategy with respect to the CAC scheme. The second result shows the comparison of tacrolimus + mycophenolate mofetil + corticosteroid (TMC) with cyclosporine + mycophenolate mofetil + corticosteroid (CMC) in which TMC was found to be a dominant alternative to CMC. CONCLUSIONS: The tacrolimus-based immunosuppression scheme is not CE in its TAC scheme, versus CAC, and is dominant in its TMC scheme, versus CMC, sensitivity analyses show that tacrolimus could become a CE alternative in any scheme used against higher cost-effectiveness threshold.

In Vitro-Based Production of Virus-Tested Babaco (Vasconcellea x heilbornii, syn. Carica pentagona) in Ecuador: An Integrated Approach to an Endangered Crop.

Babaco (Vasconcellea x heilbornii), a fruit-bearing vegetatively propagated crop native to Ecuador, is appreciated for its distinctive flavor and nutritional properties. The aim of this research was to determine a functional protocol for tissue culture propagation of virus-free babaco plants including in vitro establishment, multiplication, rooting, and acclimation. First, symptomless babaco plants from a single commercial nursery were analyzed for virus detection and cared for using different disinfection treatments in the greenhouse to reduce contamination during the in vitro establishing step, and three cytokinins, 6-(γ,γ-Dimethylallylamino) purine (2IP), 6-Benzylaminopurine (BAP), and Thidiazuron (TDZ), were used to determine the best hormone for multiplication. The best treatment for plant disinfection was the weekly application of copper sulfate at the greenhouse and a laboratory disinfection using ethanol (EtOH) (70%), Clorox (2%), and a solution of povidone iodine (2.5%), with an 80% survival during in vitro plant establishment. TDZ showed a better multiplication rate when compared with other hormones, and 70% of the rooted plants were successfully acclimated at the greenhouse. Generated plants were virus-free when tested against babaco mosaic virus (BabMV) and papaya ringspot virus (PRSV), two of the most important viruses that can affect babaco. An efficient protocol to produce virus-free babaco plants was elaborated with an integrated use of viral diagnostic tools to ensure the production of healthy start material to farmers.

The Virome of Babaco (Vasconcellea × heilbornii) Expands to Include New Members of the Rhabdoviridae and Bromoviridae.

Babaco (Vasconcellea × heilbornii) is a subtropical species in the Caricaceae family. The plant is native to Ecuador and represents an important crop for hundreds of families. The objective of this study was to characterize, at the genomic level, two new babaco viruses identified by high-throughput sequencing. The viruses, an ilarvirus and a nucleorhabdovirus, were found in a symptomatic babaco plant from a commercial nursery in the Azuay province of Ecuador. The tripartite genome of the new ilarvirus, provisionally named babaco ilarvirus 1 (BabIV-1), is related to subgroup 3 ilarviruses, including apple mosaic virus, apple necrotic mosaic virus, and prunus necrotic ringspot virus as the closest relatives. The genome of the nucleorhabdovirus, provisionally named babaco nucleorhabdovirus 1 (BabRV-1), showed the closest relation with joa yellow blotch-associated virus and potato yellow dwarf nucleorhabdovirus. Molecular-based detection methods found BabIV-1 and BabRV-1 in 21% and 36%, respectively, of plants surveyed in a commercial babaco nursery, highlighting the importance of enforcing virus testing and nursery certification programs for babaco.

Identification and genetic characterization of a new totivirus from Bursera graveolens in western Ecuador.

The complete genomic sequence of a previously uncharacterized virus provisionally named "Bursera graveolens associated totivirus 1" (BgTV-1) was obtained from Bursera graveolens (Kunth) Triana & Planch., a tree known as "palo santo" in Ecuador. The BgTV-1 genome is a monopartite double-stranded RNA (dsRNA) that is 4794 nucleotides (nt) long (GenBank accession number ON988291). Phylogenetic analysis of the capsid protein (CP) and RNA-dependent RNA polymerase (RdRp) placed BgTV-1 in a clade with other plant-associated totiviruses. Amino acid (aa) sequence comparisons of putative BgTV-1 proteins showed the highest sequence similarity to those of taro-associated totivirus L (QFS21890.1-QFS21891.1) and Panax notoginseng virus A (YP_009225664.1- YP_009225665.1), with 51.4% and 49.8% identity, respectively, in the CP and 56.4% and 55.2% identity, respectively, in the RdRp. BgTV-1 was not detected in total RNA from either of the two endophytic fungi cultured from BgTV-1-positive B. graveolens leaves, suggesting that BgTV-1 may be a plant-infecting totivirus. Based on its distinct host and the low aa sequence similarity between the CP of BgTV-1 and its counterparts from the closest relatives, the virus described in this study should be assigned as a new member of the genus Totivirus.

Papaya Sticky Disease Caused by Virus "Couples": A Challenge for Disease Detection and Management.

Papaya sticky disease (PSD) is a major virus disorder of papaya (Carica papaya). The disease is characterized by fruit damage caused by the oxidation of spontaneously exuded latex. In Brazil, PSD is caused by the coinfection of two viruses, papaya meleira virus (PMeV), a toti-like virus, and papaya meleira virus-2 (PMeV-2), an umbra-like virus. The disorder has also been reported in Mexico and, more recently, in Australia, but the presence of both PMeV and PMeV-2 in symptomatic plants has been documented only in Brazil. In 2021, 2-year-old papaya plants (cultivar Passion Red) exhibiting PSD-like symptoms were observed in Santa Elena Province, Ecuador. Molecular tests of leaf tissue and fruit latex from symptomatic plants failed to detect PMeV. However, papaya virus Q (PpVQ), an umbra-like virus related to but distinct from PMeV-2, and a novel virus, tentatively named papaya sticky fruit-associated virus (PSFaV), were found in the symptomatic samples. PSFaV shares 56% nucleotide identity with the genome of PMeV, suggesting that PSD symptoms can be caused by "couples" of viruses related to but distinct from PMeV (a toti-like virus) and PMeV-2 (an umbra-like virus). This review discusses the history and epidemiology of PSD and the genomic features of newly discovered virus couples involved in this syndrome. Given the unusual etiology of PSD, which involves distinct virus species, the importance of implementing proper diagnostic approaches for PSD is highlighted.

A long-run convergence analysis of aerosol precursors, reactive gases, and aerosols in the BRICS and Indonesia: is a global emissions abatement agenda supported?

This article examines the hypothesis of deterministic emissions convergence for a panel of the BRICS and Indonesia to advanced countries' emissions levels as well as to Sweden (which is a country that has clearly gone through decoupling) using a novel dataset with ten series of annual estimates of anthropogenic emissions comprising aerosols, aerosol precursor and reactive compounds, and carbon dioxide from 1820 to 2018. For that purpose, we employ four novel panel unit root tests allowing for several forms of time-dependent and state-dependent nonlinearity. The evidence supports deterministic convergence following a linear process for carbon dioxide, whereas the adjustment is asymmetric and nonlinear for carbon monoxide. Methane and nitrogen oxides exhibit logistic smooth transition converging dynamics. In contrast, black carbon, ammonia, nitrous oxide, non-methane volatile organic compounds, organic carbon, and sulfur dioxide emissions diverge. These results have implications for the abatement of greenhouse gases emissions at the global level, given the high share of emissions of the BRICS.

First report of Neoscytalidium dimidiatum causing stem canker on yellow dragon fruit (Hylocereus megalantus) in Ecuador.

Dragon fruit cultivation is an emerging industry in Ecuador. In August of 2020, yellow dragon fruit plants (Hylocereus megalantus) showing brown hardened scabs on cladodes and fruits were observed in a field in Guayas, a coastal province of Ecuador (Fig. 1A). Symptoms were observed in ~ 40% of the assessed plants (n=100) with damage varying from mild (necrotic spots) to severe (canker). Ten cladode sections of ~ 10 cm2 with signs of canker were collected from five affected plants (two from each plant). Symptomatic cladode sections were sliced, surface-sterilized with a solution of 1% sodium hypochlorite, rinsed with sterile water, transferred into potato dextrose agar (PDA) media, and incubated at 28°C for five days in the dark. Three fungal isolates recovered from the cladodes produced colonies with dense dark aerial mycelia that matched the morphological description for Neoscytalidium dimidiatum (Crous et al 2006) (Fig 1B, 1C). Arthric chains of cylindrical conidia were observed under the microscope and presented zero or one septum with sizes between 10.9 ± 0.27 x 4.97 ± 0.36 µm (n=50). Pycnidia produced ellipsoid-shaped conidia, and sizes ranged from 4.5 ± 0.3 x 11.02 ± 0.5 µm (n=50). Cultured isolates were subjected to DNA extractions using the fungal DNA mini kit (Omega, Bio-Tek, Inc) for molecular identification by amplifying the 5.8S rDNA and adjacent internal transcriber spacer (ITS) 1 and 2 regions using primers (ITS1 / ITS4) as described (White et al., 1990). In addition, the ß-tubulin and elongation factor 1-α targets were amplified by primers Bt2a / Bt2b (Glass and Donaldson, 1995) and EF1-728 F / EF1-986R (Carbone and Kohn, 1999), respectively, following the recommended PCR conditions. Amplified products were cloned using a pGEMT-easy kit (Promega, USA) and sequenced. Sequence comparisons for each target revealed that the three isolates were 100% identical to each other. Sequences obtained from a single plant were submitted to NCBI Genbank and assigned acc. Numbers OP377444, OP381216, and OP381217, for the ITS, ß-tubulin, and elongation factor, respectively. BLAST analyses of the three amplified targets confirmed homology to counterparts from N. dimitiatum, with 99-100 % identities to isolates from China (JX524168), United Arab Emirates (MN447201), and Israel (KF020895). To fulfill Koch´s postulates, thirteen 4-month-old healthy plants were inoculated either with the pathogen (n=10) or mock-inoculated (n=3). In addition, two detached yellow dragon fruits and a mock were inoculated following the same protocol as stems. Inoculation was performed by making small wounds on cladodes or fruits using a sterile needle and placing a 2-mm agar plug containing mycelia from a 7-day-old colony. For mock inoculations, 2-mm plugs with clean PDA media were used. The inoculated area was wrapped with black plastic film for seven days at 27 to 32°C. At ten days post-inoculation, brown scab lesions with an orange halo were observed in the inoculated plants but not in the mock-inoculated plants and fruit (Fig. 1D, 1E). N. dimidiatum was re-isolated from experimentally-induced canker lesions, and morphologically identified. Stem canker caused by N. dimidiatum is a severe disease affecting dragon fruit production worldwide (Chuang et al., 2021). In Ecuador, this pathogen was found affecting yellow dragon fruit (H. megalantus) under natural conditions; however, under experimental conditions, red dragon fruit (H. undatus), which is widely produced in several coastal provinces of the country, was also found to be susceptible. Further studies are needed to investigate epidemiological aspects of this important pathogen, which threatens dragon fruit production in Ecuador.

An Unwanted Association: The Threat to Papaya Crops by a Novel Potexvirus in Northwest Argentina.

An emerging virus isolated from papaya (Carica papaya) crops in northwestern (NW) Argentina was sequenced and characterized using next-generation sequencing. The resulting genome is 6667-nt long and encodes five open reading frames in an arrangement typical of other potexviruses. This virus appears to be a novel member within the genus Potexvirus. Blast analysis of RNA-dependent RNA polymerase (RdRp) and coat protein (CP) genes showed the highest amino acid sequence identity (67% and 71%, respectively) with pitaya virus X. Based on nucleotide sequence similarity and phylogenetic analysis, the name papaya virus X is proposed for this newly characterized potexvirus that was mechanically transmitted to papaya plants causing chlorotic patches and severe mosaic symptoms. Papaya virus X (PapVX) was found only in the NW region of Argentina. This prevalence could be associated with a recent emergence or adaptation of this virus to papaya in NW Argentina.

Phylodynamics and Coat Protein Analysis of Babaco Mosaic Virus in Ecuador.

Babaco is a fast-growing herbaceous shrub with great commercial potential because of the organoleptic properties of its fruit. Babaco mosaic virus (BabMV) is a potexvirus in the family Alphaflexiviridae affecting babaco in all the provinces that produce this crop in Ecuador. BabMV was recently described but it has been affecting babaco for decades and, since many potexviruses are serologically indistinguishable, it may have been previously misidentified as papaya mosaic virus. Based on the coat protein (CP) gene, we aimed to study the distribution and epidemiological patterns of BabMV in babaco and chamburo over the years and to model its three-dimensional structure. Sequences of the CP were obtained from thirty-six isolates from plants collected in the main babaco-producing provinces of Ecuador between 2016 and 2021. The evolution rate of BabMV was estimated at 1.21 × 10-3 nucleotide substitutions site-1 year-1 and a time of origin of the most recent common ancestor around 1958.80. From molecular dynamics simulations, compared to other proteins of BabMV-RDRP, TGB1, and Alkb domain-the CP exhibited a higher flexibility with the C and N terminals as the most flexible regions. The reconstructed viral distribution provides dispersion patterns which have implications for control approaches of BabMV.

Two new umbravirus-like associated RNAs (ulaRNAs) discovered in maize and johnsongrass from Ecuador.

Two new umbravirus-like associated RNAs (ulaRNAs) were found, respectively, in maize and Johnsongrass samples from Ecuador. The complete sequences consist of 3,053 and 3,025 nucleotides, respectively, and contain four open reading frames (ORFs). Their genome sequences were 58% identical to each other and 28 to 60% identical to the most closely related viruses. Phylogenetic analysis using full genome sequences and amino acid sequence of the RNA-dependent-RNA polymerase (RdRp) placed both sequences in a clade sharing the most recent common ancestor with ulaRNAs from sugarcane and maize, suggesting that they belong to a monophyletic grass-infecting lineage. Their terminal regions exhibit features common to umbraviruses and ulaRNAs.

Genome Characterization and Pathogenicity of Two New Hyptis pectinata Viruses Transmitted by Distinct Insect Vectors.

Two newly described viruses belonging to distinct families, Rhabdoviridae and Geminiviridae, were discovered co-infecting Hyptis pectinata from a tropical dry forest of Ecuador. The negative-sense RNA genome of the rhabdovirus, tentatively named Hyptis latent virus (HpLV), comprises 13,765 nucleotides with seven open reading frames separated by the conserved intergenic region 3'-AAUUAUUUUGAU-5'. Sequence analyses showed identities as high as 56% for the polymerase and 38% for the nucleocapsid to members of the genus Cytorhabdovirus. Efficient transmission of HpLV was mediated by the pea aphid (Acyrthosiphon pisum) in a persistent replicative manner. The single-stranded DNA genome of the virus tentatively named Hyptis golden mosaic virus (HpGMV) shared homology with members of the genus Begomovirus with bipartite genomes. The DNA-A component consists of 2,716 nucleotides (nt), whereas the DNA-B component contains 2,666 nt. Pairwise alignments using the complete genomic sequence of DNA-A of HpGMV and closest relatives showed identities below the cutoff (<91% shared nt) established by the ICTV as species demarcation, indicating that HpGMV should be classified in a distinct begomovirus species. Transmission experiments confirmed that the whitefly Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) is a vector of HpGMV.

Characterization of a new potyvirus infecting Thevetia ahouai in Ecuador.

A new potyvirus was found in Thevetia ahouai L. (Fam. Apocynaceae) plants exhibiting white spots on leaves and fruit discoloration in Ecuador. The complete genome sequences of two isolates of this virus, tentatively named "thevetia white spot virus" (ThWSV), were determined and found to be 9,912 (isolate 1) and 9,904 (isolate 2) nucleotides (nt) in length, each encoding a polyprotein of 363 kDa. Sequence comparisons between the two isolates showed 80 and 87% identity at the nt and amino acid (aa) level, respectively, whereas the overall sequence identity between ThWSV and its closest relative was 69% and 71% at the nt and aa level, respectively.

Transmission and Pathogenicity of Papaya Virus E: Insights from an Experimental Papaya Orchard.

A study was conducted to investigate epidemiological aspects of papaya virus E (PpVE), a cytorhabdovirus commonly found in papaya (Carica papaya L.) plantings in Ecuador. Besides papaya, PpVE was found in three Fabaceae weeds, including Rhynchosia minima, Centrosema plumieri, and Macroptilium lathyroides, the latter being the species with the highest virus prevalence. Greenhouse experiments showed that in M. lathyroides, single infections of PpVE induce only mild leaf mosaic, whereas in mixed infections with cowpea severe mosaic virus, PpVE contributes to severe mosaic. In papaya, PpVE did not induce noticeable symptoms in single or mixed infections with papaya ringspot virus. Transmission experiments confirmed that whiteflies (Bemisia tabaci) transmit PpVE in a semipersistent, nonpropagative manner.

Estimating cost-effectiveness thresholds under a managed healthcare system: experiences from Colombia.

Like most of the world, low- and middle-income countries have faced a growing demand for new health technologies and higher budget constraints. It is necessary to have technical instruments to make decisions based on real-world evidence that allows maximization of the population's health with a limited budget. We estimated the supply-based cost-effectiveness elasticity, which was then used to determine the cost-effectiveness threshold for the healthcare system of Colombia, a middle-income country where multiple insurers, paid under capitation rules, manage the compulsory contributions of the citizens and government subsidies. Using administrative data, we explored the variation of health expenditures and outcomes at the insurer, geographical region, diagnosis group and year levels. To deal with endogeneity in a two-way fixed-effects model, we instrumented health expenditures using characteristics of the health system such as drug-price regulation. We estimated the threshold to be US$4487.5 per years of life lost avoided [14.7 million Colombian pesos (COP) at 2019 prices] and US$5180.8 per quality-adjusted life-years gained (17 million COP at 2019 prices), around one times the gross domestic product GDP per capita. To the best of our knowledge, this is the first estimation of the cost-effectiveness threshold elasticity supply-based in a middle-income country with a managed healthcare system.

Control of tissue homeostasis, tumorigenesis, and degeneration by coupled bidirectional bistable switches.

The Hippo-YAP/TAZ signaling pathway plays a critical role in tissue homeostasis, tumorigenesis, and degeneration disorders. The regulation of YAP/TAZ levels is controlled by a complex regulatory network, where several feedback loops have been identified. However, it remains elusive how these feedback loops contain the YAP/TAZ levels and maintain the system in a healthy physiological state or trap the system in pathological conditions. Here, a mathematical model was developed to represent the YAP/TAZ regulatory network. Through theoretical analyses, three distinct states that designate the one physiological and two pathological outcomes were found. The transition from the physiological state to the two pathological states is mechanistically controlled by coupled bidirectional bistable switches, which are robust to parametric variation and stochastic fluctuations at the molecular level. This work provides a mechanistic understanding of the regulation and dysregulation of YAP/TAZ levels in tissue state transitions.

An umbra-related virus found in babaco (Vasconcellea × heilbornii).

The complete sequence of a new viral RNA from babaco (Vasconcellea × heilbornii) was determined. The genome consisted of 4,584 nucleotides, containing two open reading frames (ORFs 1 and 2), a 9-nt-long noncoding region (NCR) at the 5' terminus, and an unusually long (1,843 nt) NCR at the 3' terminus. The presence of a potential heptameric slippery signal located 12 nt upstream the stop codon of ORF 1 suggests a -1 ribosomal frameshift mechanism for the translation of ORF 2. Sequence comparisons of ORF 2 revealed similarity to the RNA-dependent RNA polymerase (RdRp) of several umbra- and umbra-like viruses. Phylogenetic analysis of the RdRp placed the new virus in a well-supported and cohesive clade that includes umbra-like viruses reported in papaya, citrus, opuntia, maize, and sugarcane hosts. Viruses of this clade share a most recent ancestor with the umbraviruses but have different genomic features. The creation of a new genus within the family Tombusviridae is proposed for the classification of these novel viruses.

Genetic characterization of a mild isolate of papaya ringspot virus type-P (PRSV-P) and assessment of its cross-protection potential under greenhouse and field conditions.

A mild isolate of Papaya ringspot virus type-P, abbreviated as PRSV-mild, from Ecuador was sequenced and characterized. The most distinguishing symptom induced by PRSV-mild was gray powder-like leaf patches radiating from secondary veins. In greenhouse experiments, PRSV-mild did not confer durable protection against a severe isolate of the virus (PRSV-sev), obtained from the same field. Furthermore, isolate specific detection in mixed-infected plants showed that PRSV-sev becomes dominant in infections, rendering PRSV-mild undetectable at 90-120 days post superinfection. Virus testing using isolate-specific primers detected PRSV-mild in two out of five surveyed provinces, with 10% and 48% of incidence in Santo Domingo and Los Ríos, respectively. Comparative genomics showed that PRSV-mild lacks two amino acids from the coat protein region, whereas amino acid determinants for asymptomatic phenotypes were not identified. Recombination events were not predicted in the genomes of the Ecuadorean isolates. Phylogenetic analyses placed both PRSV-mild and PRSV-sev in a clade that includes an additional PRSV isolate from Ecuador and others from South America.