Search Results (62)

Detection of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimp aquaculture is complicated by endogenous viral elements (EVEs) causing false positives in conventional PCR assays. This study analyzed 277 Penaeus vannamei samples from Ecuador using World Organization for Animal Health (WOAH)-recommended short-fragment primers (IHHNV-309, -389, -392, -77012; ~1.5 kb amplicons) and long-amplicon PCR (LA-PCR; ~3.7 kb, 90% of the genome), complemented by histopathology. Short-fragment primers showed high positivity rates (72.9–83.0% individually; 69.3% combined), while LA-PCR reduced positives to 29.6%, with 95.1% overlap indicating true infections as a subset of conventional results. Approximately 55.6% of samples likely contained EVEs mimicking IHHNV, and 14.8% were true negatives. Histopathology confirmed classic IHHNV lesions (Cowdry A-type inclusions) in only one sample (0.36%), which also showed co-infections (hepatopancreatic atrophy, gregarines, and unidentified viral inclusions), suggesting multifactorial pathology. These findings highlight inflated IHHNV prevalence due to single-primer PCR, particularly in Ecuador, where reliance on WOAH-suggested primers (e.g., 389F/R) fails to distinguish infectious IHHNV from EVEs or confirm subclinical status, risking misattribution of losses to IHHNV while overlooking pathogens like Vibrio spp. We advocate LA-PCR and histopathology to enhance diagnostics and support sustainable shrimp fisheries. Full article

This article provides a comprehensive analysis of Virus-Induced Gene Silencing (VIGS), which is an effective tool for studying the functional genomics of organisms that are poorly amenable to genomic editing. The VIGS method is grounded in the plant’s post-transcriptional gene silencing (PTGS) machinery and utilizes recombinant viral vectors to trigger systemic suppression of endogenous plant gene expression, leading to visible phenotypic changes that enable gene function characterization. This article details the application of VIGS in model organisms (Arabidopsis thaliana, Nicotiana benthamiana) and a wide range of crops, with a special focus on the Solanaceae family, particularly pepper (Capsicum annuum L.). This review analyzes the design and structural elements of viral vectors used for VIGS, such as Tobacco Rattle Virus (TRV), Broad Bean Wilt Virus 2 (BBWV2), Cucumber Mosaic Virus (CMV), geminiviruses (CLCrV, ACMV), and satellite virus-based systems. It also critically examines the key factors that determine silencing efficiency. These factors encompass insert design, agroinfiltration methodology, plant developmental stage, agroinoculum concentration, plant genotype, and environmental factors (temperature, humidity, photoperiod). Particular attention is given to optimization strategies, such as the use of viral suppressors of RNA silencing (VSRs). This article concludes with the achievements in using VIGS to identify pepper genes governing fruit quality (color, biochemical composition, pungency), resistance to biotic (bacteria, oomycetes, insects) and abiotic (temperature, salt, osmotic stress) factors, as well as genes regulating plant architecture and development. The results obtained demonstrate the advantages and limitations of VIGS, alongside future perspectives for its integration with multi-omics technologies to accelerate breeding and advance functional genomics studies in pepper. Full article

Bats are natural reservoirs for diverse viruses, yet they rarely develop disease, suggesting unique antiviral adaptations. In this study, we performed a comprehensive genome-wide analysis in the common vampire bat (Desmodus rotundus), integrating comparative genomics, functional annotation, microRNA (miRNA) discovery, target prediction, and network-based analyses. Comparative genomic analysis revealed that Phyllostomus discolor exhibits the highest protein homology (97.4%) with D. rotundus. Alignment of interferon regulatory factors (IRFs) indicated strong conservation of IRF1, IRF5, and IRF8, while IRF4 and IRF7 showed divergence, reflecting bat-specific modulation of interferon signaling. Functional annotation of previously uncharacterized proteins identified immune-related elements, including toll-like receptor 4, syncytin-1, and endogenous retroviral sequences, highlighting the integration of viral components into host immunity. We further identified 19 novel miRNAs in D. rotundus, with high-confidence target genes such as SOD2, TRIM28, and FGFR1 involved in antiviral defense, apoptosis regulation, and oxidative stress response. Functional enrichment analyses revealed processes associated with wound healing, apoptosis suppression, infection response, and longevity. Network entropy analysis highlighted central regulatory hubs, including MYC, BCL2, and KIF1B, influencing cell cycle, survival, and immune balance. Collectively, these results demonstrate that D. rotundus employs an integrated regulatory network combining conserved immune factors, lineage-specific gene divergence, and miRNA-mediated fine-tuning to achieve viral tolerance without pathology. This study expands our understanding of bat antiviral biology and provides candidate molecular targets for future functional and translational research. Full article

The whitefly Bemisia tabaci (Hemiptera: Aleyrodoidea) causes direct feeding damage to crop plants and transmits pathogenic plant viruses, thereby threatening global food security. Although whitefly-infecting RNA viruses are known and proposed as biocontrol agents, no insect DNA virus has been found in any member of Aleyrodoidea. Using rolling circle amplification (RCA) of viral DNA from whiteflies collected from crop fields in Morocco, followed by Illumina sequencing of the RCA products, we found a novel insect single-stranded (ss) DNA parvovirus (family Parvoviridae) in addition to plant ssDNA geminiviruses transmitted by whiteflies. Based on its genome organization with inverted terminal repeats and evolutionarily conserved proteins mediating viral DNA replication (NS1/Rep) and encapsidation (VP), encoded on the forward and reverse strands, respectively, we named this virus Bemisia tabaci ambidensovirus (BtaDV) and classified it as a founding member of a new genus within the subfamily Densovirinae. This subfamily also contains three distinct genera of ambisense densoviruses of other hemipteran insects (Aphidoidea, Coccoidea, and Psylloidea). Furthermore, we provide evidence for the genetic variants of BtaDV circulating in whitefly populations and for its partial sequences integrated into the B. tabaci genome, with one integrant locus potentially expressing a fusion protein composed of viral Rep endonuclease and host DNA-binding domains. This suggests a long-term virus-host interaction and neofunctionalization of BtaDV-derived endogenous viral elements. Full article

Endogenous viral elements (EVEs) are genomic sequences derived from viruses. Some EVEs have open reading frames (ORFs) that can express co-opted proteins in their host. Furthermore, some EVEs that are expressed as proteins have become part of cellular genes that are fusions of hosts and EVE sequences. Endogenous parvoviral elements (EPVs) are highly represented in mammalian genomes, and some of them contain ORFs and can be expressed as proteins. We have shown that an EPV containing an ORF is part of the guinea pig gene enRep-M9l. This gene is broadly transcribed in vivo, indicating that it can be translated into a protein. By generating antibodies against the enRep coding sequence of the enRep-M9l ORF, we showed that the protein enRep-M9l is expressed in vivo and in the guinea pig-derived cell line JH4. By immunofluorescence and in situ proximity ligation assays, we observed that enRep-M9l protein has a cytoplasmic localization near microtubules. The results of this study suggest that the guinea pig EPV-derived protein enRep-M9l is a microtubule-associated protein. To our knowledge, this is the second demonstration that an EPV-derived protein is expressed in vivo. Full article

Prochlorococcus, a cyanobacteria genus of the smallest and most abundant oceanic phototrophs, encompasses ecotype strains adapted to high-light (HL) and low-light (LL) niches. To elucidate the adaptive evolution of this genus, we analyzed 40 Prochlorococcus marinus ORFeomes, including two cornerstone strains, MED4 and NATL1A. Employing deep learning with robust statistical methods, we detected new protein family distributions in the strains and identified key genes differentiating the HL and LL strains. The HL strains harbor genes (ABC-2 transporters) related to stress resistance, such as DNA repair and RNA processing, while the LL strains exhibit unique chlorophyll adaptations (ion transport proteins, HEAT repeats). Additionally, we report the finding of variable, depth-dependent endogenous viral elements in the 40 strains. To generate biological resources to experimentally study the HL and LL adaptations, we constructed the ORFeomes of two representative strains, MED4 and NATL1A synthetically, covering 99% of the annotated protein-coding sequences of the two species, totaling 3976 cloned, sequence-verified open reading frames (ORFs). These comparative genomic analyses, paired with MED4 and NATL1A ORFeomes, will facilitate future genotype-to-phenotype mappings and the systems biology exploration of Prochlorococcus ecology. Full article

Endogenous viral elements (EVEs) have been reported to exist widely in the genomes of eukaryotic organisms, and they are closely associated with the growth, development, genetics, adaptation, and evolution of their hosts. In this study, two methods—homologous sequence search and genome alignment—were used to explore the endogenous viral sequences in the genomes of Fragaria species. Results revealed abundant endogenous pararetroviruses (EPRVs) in the genomes of Fragaria species, including 786 sequences belonging to five known taxa such as Caulimovirus and other unclassified taxa. Differences were observed in the detected EPRVs between the two methods, with the homologous sequence search having a greater number of EPRVs. On the contrary, genome alignment identified various types and sources of virus-like sequences. Furthermore, through genome alignment, a 267-bp sequence with 95% similarity to the gene encoding the aphid-transmitted protein of Strawberry vein banding virus (Caulimovirus venafragariae) was discovered in the F. chiloensis genome, which was likely a recent insertion. In addition, the statistical analysis of the genome alignment results indicated a remarkably higher abundance of virus-like sequences in the genomes of polyploid strawberries compared with diploid ones. Moreover, the differences in virus-like sequences were observed between the genomes of Fragaria species and those of their close relatives. This study enriched the diversity of viruses that infect strawberries, and laid a theoretical foundation for further research on the origin of endogenous viruses in the strawberry genome, host–virus interactions, adaptation, evolution, and their functions. Full article

Bats are ecologically diverse vertebrates characterized by their ability to host a wide range of viruses without apparent illness and the presence of numerous endogenous viral elements (EVEs). EVEs are well preserved, expressed, and may affect host biology and immunity, but their role in bat immune system evolution remains unclear. Among EVEs, endogenous bornavirus-like elements (EBLs) are bornavirus sequences integrated into animal genomes. Here, we identified a novel EBL in the microbat Myotis daubentonii, EBLL-Cultervirus.10-MyoDau (short name is CV.10-MyoDau) that shows protein-level conservation with the L-protein of a Cultervirus (Wuhan sharpbelly bornavirus). Surprisingly, we discovered a transcript on the antisense strand comprising three exons, which we named AMCR-MyoDau. The active transcription in Myotis daubentonii tissues of AMCR-MyoDau, confirmed by RNA-Seq analysis and RT-PCR, highlights its potential role during viral infections. Using comparative genomics comprising 63 bat genomes, we demonstrate nucleotide-level conservation of CV.10-MyoDau and AMCR-MyoDau across various bat species and its detection in 22 Yangochiropera and 12 Yinpterochiroptera species. To the best of our knowledge, this marks the first occurrence of a conserved EVE shared among diverse bat species, which is accompanied by a conserved antisense transcript. This highlights the need for future research to explore the role of EVEs in shaping the evolution of bat immunity. Full article

In this study, we investigated the potential involvement of endogenous viral elements (EVEs) in the development of apical tissue necrosis, resulting in the terminal abortion of upland cotton (Gossypium hirsutum L.) in Georgia. The high-throughput sequence analysis of symptomatic and asymptomatic plant tissue samples revealed near-complete EVE-Georgia (EVE-GA) sequences closely related to caulimoviruses. The analysis of EVE-GA’s putative open reading frames (ORFs) compared to cotton virus A and endogenous cotton pararetroviral elements (eCPRVE) revealed their similarity in putative ORFs 1–4. However, in the ORF 5 and ORF 6 encoding putative coat protein and reverse transcriptase, respectively, the sequences from EVE-GA have stop codons similar to eCPRVE sequences from Mississippi. In silico mining of the cotton genome database using EVE-GA as a query uncovered near-complete viral sequence insertions in the genomes of G. hirsutum species (~7 kb) but partial in G. tomentosum (~5.3 kb) and G. mustelinum (~5.1 kb) species. Furthermore, cotton EVEs’ episomal forms and messenger RNA (mRNA) transcripts were detected in both symptomatic and asymptomatic plants collected from cotton fields. No significant yield difference was observed between symptomatic and asymptomatic plants of the two varieties evaluated in the experimental plot. Additionally, EVEs were also detected in cotton seeds and seedlings. This study emphasizes the need for future research on EVE sequences, their coding capacity, and any potential role in host immunity or pathogenicity. Full article

In this study, we analyzed the potential of viral infections in the species Homo sapiens as environmental causes of orofacial clefts (OFCs). A scoring system was adapted for qualitatively assessing the potential of viruses to cause cleft lip and/or palate (CL/P). This assessment considered factors such as information from the literature, nucleotide and amino acid similarities, and the presence of Endogenous Viral Elements (EVEs). The analysis involved various algorithm packages within Basic Local Alignment Search Tool 2.13.0 software and databases from the National Center for Biotechnology Information and the International Committee on Taxonomy of Viruses. Twenty significant viral species using different biosynthesis strategies were identified: Human coronavirus NL63, Rio Negro virus, Alphatorquevirus homin9, Brisavirus, Cosavirus B, Torque teno mini virus 4, Bocaparvovirus primate2, Human coronavirus HKU1, Monkeypox virus, Mammarenavirus machupoense, Volepox virus, Souris mammarenavirus, Gammapapillomavirus 7, Betainfluenzavirus influenzae, Lymphocytic choriomeningitis mammarenavirus, Ledantevirus kern, Gammainfluenzavirus influenzae, Betapolyomavirus hominis, Vesiculovirus perinet, and Cytomegalovirus humanbeta5. The evident viral etiological potential in relation to CL/P varies depending on the Baltimore class to which the viral species belongs. Given the multifactorial nature of CL/P, this relationship appears to be dynamic. Full article

Sandflies are known vectors of leishmaniasis. In the Old World, sandflies are also vectors of viruses while little is known about the capacity of New World insects to transmit viruses to humans. Here, we relate the identification of RNA sequences with homology to rhabdovirus nucleocapsids (NcPs) genes, initially in the Lutzomyia longipalpis LL5 cell lineage, named NcP1.1 and NcP2. The Rhabdoviridae family never retrotranscribes its RNA genome to DNA. The sequences here described were identified in cDNA and DNA from LL-5 cells and in adult insects indicating that they are transcribed endogenous viral elements (EVEs). The presence of NcP1.1 and NcP2 in the L. longipalpis genome was confirmed in silico. In addition to showing the genomic location of NcP1.1 and NcP2, we identified another rhabdoviral insertion named NcP1.2. Analysis of small RNA molecules derived from these sequences showed that NcP1.1 and NcP1.2 present a profile consistent with elements targeted by primary piRNAs, while NcP2 was restricted to the degradation profile. The presence of NcP1.1 and NcP2 was investigated in sandfly populations from South America and the Old World. These EVEs are shared by different sandfly populations in South America while none of the Old World species studied presented the insertions. Full article

Parasitoid wasps are fundamental insects for the biological control of agricultural pests. Despite the importance of wasps as natural enemies for more sustainable and healthy agriculture, the factors that could impact their species richness, abundance, and fitness, such as viral diseases, remain almost unexplored. Parasitoid wasps have been studied with regard to the endogenization of viral elements and the transmission of endogenous viral proteins that facilitate parasitism. However, circulating viruses are poorly characterized. Here, RNA viromes of six parasitoid wasp species are studied using public libraries of next-generation sequencing through an integrative bioinformatics pipeline. Our analyses led to the identification of 18 viruses classified into 10 families (Iflaviridae, Endornaviridae, Mitoviridae, Partitiviridae, Virgaviridae, Rhabdoviridae, Chuviridae, Orthomyxoviridae, Xinmoviridae, and Narnaviridae) and into the Bunyavirales order. Of these, 16 elements were described for the first time. We also found a known virus previously identified on a wasp prey which suggests viral transmission between the insects. Altogether, our results highlight the importance of virus surveillance in wasps as its service disruption can affect ecology, agriculture and pest management, impacting the economy and threatening human food security. Full article

Multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocytes glycoprotein-antibody disease (MOGAD) are distinct autoimmune demyelinating disorders characterized by varying clinical and pathological characteristics. While the precise origins of these diseases remain elusive, a combination of genetic and environmental factors, including viral elements, have been suggested as potential contributors to their development. Our goal was to assess the occurrence of antibodies against pathogenic peptides associated with Epstein–Barr virus (EBV) and the human endogenous retrovirus-W (HERV-W) in serum samples obtained from Japanese individuals diagnosed with MS, NMOSD, and MOGAD and to make comparisons with a group of healthy controls (HCs). We conducted a retrospective analysis involving 114 Japanese participants, comprising individuals with MS (34), NMOSD (20), MOGAD (20), and HCs (40). These individuals were tested using a peptide-based enzyme-linked immunosorbent assay. A marked increase in antibody response against EBV nuclear antigen 1 (EBNA1)_386–405 was observed in the serum of MS and MOGAD patients, as compared to HCs. Notably, we observed a correlation between antibodies against EBNA1_386–405 and HERV-W_486–504 peptides in a subset of the antibody-positive MS patients. These findings emphasize the involvement of EBV in the pathogenesis of MS and potentially MOGAD, suggesting its role in the reactivation of HERV-W. Full article

Human endogenous retroviruses (HERVs) comprise a significant portion of the human genome, making up roughly 8%, a notable comparison to the 2–3% represented by coding sequences. Numerous studies have underscored the critical role and importance of HERVs, highlighting their diverse and extensive influence on the evolution of the human genome and establishing their complex correlation with various diseases. Among HERVs, the HERV-K (HML-2) subfamily has recently attracted significant attention, integrating into the human genome after the divergence between humans and chimpanzees. Its insertion in the human genome has received considerable attention due to its structural and functional characteristics and the time of insertion. Originating from ancient exogenous retroviruses, these elements succeeded in infecting germ cells, enabling vertical transmission and existing as proviruses within the genome. Remarkably, these sequences have retained the capacity to form complete viral sequences, exhibiting activity in transcription and translation. The HERV-K (HML-2) subfamily is the subject of active debate about its potential positive or negative effects on human genome evolution and various pathologies. This review summarizes the variation, regulation, and diseases in human genome evolution arising from the influence of HERV-K (HML-2). Full article

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections in the host genome. Although mutations and silencing mechanisms impair their original role in viral replication, HERVs are believed to play roles in various biological processes. Long interspersed nuclear elements (LINEs) are non-LTR retrotransposons that have a lifecycle resembling that of retroviruses. Although LINE expression is typically silenced in somatic cells, it also contributes to various biological processes. The aberrant expression of HERVs and LINEs is closely associated with the development of cancer and/or immunological diseases, suggesting that they are integrated into various pathways related to the diseases. HERVs/LINEs control gene expression depending on the context as promoter/enhancer elements. Some RNAs and proteins derived from HERVs/LINEs have oncogenic potential, whereas others stimulate innate immunity. Non-retroviral endogenous viral elements (nrEVEs) are a novel type of virus-like element in the genome. nrEVEs may also be involved in host immunity. This article provides a current understanding of how these elements impact cellular physiology in cancer development and innate immunity, and provides perspectives for future studies. Full article