Single amino acid change in tomato brown rugose fruit virus breaks virus-specific resistance in new resistant tomato cultivar.

Introduction: Tomato cultivation across the world is severely affected by emerging plant viruses. An effective method for protection of commercial crops against viral threats is the use of cultivars harboring resistance genes. Tomato brown rugose fruit virus (ToBRFV), a recently emerged tobamovirus, is able to overcome the dominant Tm-22 resistance that is present in the majority of commercial tomato cultivars. In an effort to alleviate the severe consequences of ToBRFV on tomato production, tomato breeding companies are developing new cultivars with varying levels of resistance against ToBRFV. Methods: In the present study, cultivars with a new resistant phenotype against ToBRFV were screened against a wild-type isolate of ToBRFV, and subsequently, their performance under commercial greenhouse conditions was monitored. Following the identification of ToBRFV symptoms in a commercial greenhouse-where both new resistant and susceptible cultivars were interplanted-these cultivars were more closely examined. Results: The presence of ToBRFV was molecularly confirmed on both cultivar types suggesting that the new resistance had been broken. High-throughput sequencing (HTS) was used to study the complete genomes of viral isolates present in the two cultivar types. The analysis revealed a single amino acid change at position 82 of the movement protein of ToBRFV in the isolate present in the new resistant cultivar compared with the isolate identified in the susceptible cultivar. Discussion: A screening bioassay, that was performed to compare the infectivity of the two ToBRFV isolates, confirmed that only the isolate with this specific amino acid change could successfully infect the resistant cultivar, overcoming the new resistance against ToBRFV.

First report of infections with isolates of the Asian genotype of Cucumber green mottle mosaic virus in cucumber crops in Belgium.

In July 2019, four rows of cucumber plants (Cucumis sativus) in a commercial glasshouse in the north of Belgium showed severe mosaic, blistering and distortion of the leaves, with symptoms resembling those caused by Cucumber green mottle mosaic virus (CGMMV). CGMMV is a Tobamovirus that mainly affects cucurbit crops worldwide (Dombrovsky et al., 2017). Phylogenetic analyses in previous studies have shown two major clades, one including isolates that were initially identified in Europe and Russia (European genotype) and the second one with isolates initially identified in Asia and Israel (Asian genotype) (Dombrovsky et al., 2017; Pitman et al., 2022; Mackie et al., 2023). A symptomatic leaf sample was collected and total RNA was isolated from 100 mg of leaf tissue (Spectrum™ Plant Total RNA kit, Sigma-Aldrich). CGMMV was detected using a one-step TaqMan RT-qPCR (Hongyun et al., 2008). High-throughput sequencing (HTS) confirmed the presence of CGMMV. The sample was prepared using the Novel enrichment technique of viromes protocol (NETOVIR protocol, Conceição-Neto et al., 2015). The leaf material was homogenized, enriched for virus-like particles and the RNA was extracted (QIAamp Viral RNA mini kit, QIAGEN). The extract was randomly amplified (Whole Transcriptome Amplification kit, Sigma Aldrich), used for library preparation (Nextera XT DNA library preparation kit, Illumina) and sequenced on a NovaSeq platform. HTS data analysis was performed using Geneious Prime software (Biomatters, Auckland, New Zealand, version 2023.2). After quality filtering and trimming, 26.7M reads were obtained (132 nt mean length). In total, 20.6M reads were mapped to two genomes KP772568 and GQ411361 (considered as reference for the Asian and European genotypes respectively) with Geneious. This revealed 100% coverage of the full sequences (6422 nt) with 99.4% and 90% nucleotide identities to the reference genomes of Asian and European genotypes, respectively. Phylogenetic analyses confirmed that isolate 2019-26A-BE, with GenBank ID OR724740, relates to the Asian genotype. The HTS data were additionally processed using the ViPER pipeline (De Coninck, 2021). The raw reads were quality filtered and trimmed, (Trimmomatic) and then used to perform de novo assembly (metaSPAdes). The produced contigs were classified using DIAMOND and visualized with KronaTools. The results showed that no other virus was detected in the sample. Finally, cucumber seedlings were inoculated using the original symptomatic sample and were grown in a research glasshouse. After 3 weeks, severe CGMMV symptoms, similar to the original symptoms observed in the commercial glasshouse, were observed in the inoculated plants. Infection with CGMMV was verified via RT-qPCR, and the isolate present in the inoculated plants was confirmed to belong to the Asian genotype via RT-PCR-RFLP (Crespo et al., 2017). Later samplings of symptomatic leaves confirmed the presence of isolates belonging to the Asian genotype of CGMMV at four other commercial glasshouse locations, specializing in cucumber crop, in Belgium in 2020, 2021 and 2023 by RT-PCR-RFLP. While the Asian genotype was previously found elsewhere in Europe (Pitman et al., 2022), to our knowledge, this is the first report of infections with isolates of this genotype in glasshouse cucumber crops in Belgium. Further investigation is required to determine the spread and impact of infections with isolates of the Asian genotype in cucumber crops in Belgium.

Endogenous Viral Elements in Shrew Genomes Provide Insights into Pestivirus Ancient History.

As viral genomic imprints in host genomes, endogenous viral elements (EVEs) shed light on the deep evolutionary history of viruses, ancestral host ranges, and ancient viral-host interactions. In addition, they may provide crucial information for calibrating viral evolutionary timescales. In this study, we conducted a comprehensive in silico screening of a large data set of available mammalian genomes for EVEs deriving from members of the viral family Flaviviridae, an important group of viruses including well-known human pathogens, such as Zika, dengue, or hepatitis C viruses. We identified two novel pestivirus-like EVEs in the reference genome of the Indochinese shrew (Crocidura indochinensis). Homologs of these novel EVEs were subsequently detected in vivo by molecular detection and sequencing in 27 shrew species, including 26 species representing a wide distribution within the Crocidurinae subfamily and one in the Soricinae subfamily on different continents. Based on this wide distribution, we estimate that the integration event occurred before the last common ancestor of the subfamily, about 10.8 million years ago, attesting to an ancient origin of pestiviruses and Flaviviridae in general. Moreover, we provide the first description of Flaviviridae-derived EVEs in mammals even though the family encompasses numerous mammal-infecting members. This also suggests that shrews were past and perhaps also current natural reservoirs of pestiviruses. Taken together, our results expand the current known Pestivirus host range and provide novel insight into the ancient evolutionary history of pestiviruses and the Flaviviridae family in general.

Phylogenomic Characterization of Lopma Virus and Praja Virus, Two Novel Rodent-Borne Arteriviruses.

Recent years have witnessed the discovery of several new viruses belonging to the family Arteriviridae, expanding the known diversity and host range of this group of complex RNA viruses. Although the pathological relevance of these new viruses is not always clear, several well-studied members of the family Arteriviridae are known to be important animal pathogens. Here, we report the complete genome sequences of four new arterivirus variants, belonging to two putative novel species. These new arteriviruses were discovered in African rodents and were given the names Lopma virus and Praja virus. Their genomes follow the characteristic genome organization of all known arteriviruses, even though they are only distantly related to currently known rodent-borne arteriviruses. Phylogenetic analysis shows that Lopma virus clusters in the subfamily Variarterivirinae, while Praja virus clusters near members of the subfamily Heroarterivirinae: the yet undescribed forest pouched giant rat arterivirus and hedgehog arterivirus 1. A co-divergence analysis of rodent-borne arteriviruses confirms that they share similar phylogenetic patterns with their hosts, with only very few cases of host shifting events throughout their evolutionary history. Overall, the genomes described here and their unique clustering with other arteriviruses further illustrate the existence of multiple rodent-borne arterivirus lineages, expanding our knowledge of the evolutionary origin of these viruses.

Genome Sequence of Ruloma Virus, a Novel Paramyxovirus Clustering Basally to Members of the Genus Jeilongvirus.

We report here the complete genome sequence of ruloma virus, a novel paramyxovirus detected in a Machangu's brush-furred rat from Tanzania. Ruloma virus has the longest orthoparamyxovirus genome reported to date and forms a sister clade to all currently known members of the genus Jeilongvirus.

Identification and expression analysis of novel splice variants of the human carcinoembryonic antigen-related cell adhesion molecule 19 (CEACAM19) gene using a high-throughput sequencing approach.

Alternative splicing is commonly involved in carcinogenesis, being highly implicated in differential expression of cancer-related genes. Recent studies have shown that the human CEACAM19 gene is overexpressed in malignant breast and ovarian tumors, possessing significant biomarker attributes. In the present study, 3' rapid amplification of cDNA ends (3' RACE) and next-generation sequencing (NGS) were used for the detection and identification of novel CEACAM19 transcripts. Bioinformatical analysis of our NGS data revealed novel splice junctions between previously annotated exons and ultimately new exons. Next, fifteen novel CEACAM19 transcripts were identified with Sanger sequencing. Additionally, their expression profile was investigated in a wide panel of human cell lines, using nested PCR with variant-specific primers. The broad expression pattern of the CEACAM19 gene, along with the fact that its overexpression has previously been associated with ovarian and breast cancer progression, indicate the potential of novel CEACAM19 transcripts as putative diagnostic and/or prognostic biomarkers.