scholarly journals Blackcurrant Leaf Chlorosis Associated Virus: Next-Generation Sequencing Reveals an Extraordinary Virus with Multiple Genomic Components Including Evidence of Circular RNA

Author(s):  
Delano James ◽  
James Phelan ◽  
Daniel Sanderson

Blackcurrant leaf chlorosis associated virus (BCLCaV) was detected recently by next-generation sequencing (NGS) and proposed as a new and distinct species in the genus Idaeovirus. Genomic components of BCLCaV that were detected and confirmed include: 1) RNA-1 that is monocistronic and encodes the replicase complex; 2) a bicistronic RNA-2 that encodes a movement protein (MP) and the coat protein (CP) of the virus, with open reading frames (ORF) that overlap by a single adenine (A) nucleotide (nt) representing the third position of an opal stop codon of the MP ORF2a and the first position of the start codon of the CP ORF2b; 3) a subgenomic form of RNA-2 (RNA-3) that contains ORF2b; and 4) a concatenated form of RNA-2 that consists of a complementary and inverted RNA-3 conjoined to the full-length RNA-2. Analysis of NGS-derived paired-end reads revealed the existence of bridge reads encompassing the 3’-terminus and 5’-terminus of RNA-2 or RNA-3 of BCLCaV. The full RNA-2 or RNA-3 could be amplified using outward facing or abutting primers; also RNA-2/RNA-3 could be detected even after three consecutive RNase R enzyme treatments with denaturation at 95 oC preceding each digestion. Evidence was obtained indicating that there are circular forms of BCLCaV RNA-2 and RNA-3.

2020 ◽  
Vol 11 ◽  
Author(s):  
Shaohua Wen ◽  
Guoping Wang ◽  
Zuokun Yang ◽  
Yanxiang Wang ◽  
Min Rao ◽  
...  

Kiwifruit (Actinidia spp.) is native to China. Viral disease–like symptoms are common on kiwifruit plants. In this study, six libraries prepared from total RNA of leaf samples from 69 kiwifruit plants were subjected to next-generation sequencing (NGS). Actinidia virus 1 (AcV-1), a tentative species in the family Closteroviridae, was discovered in the six libraries. Two full-length and two near-full genome sequences of AcV-1 variants were determined by Sanger sequencing. The genome structure of these Chinese AcV-1 variants was identical to that of isolate K75 and consisted of 12 open reading frames (ORFs). Analyses of these sequences together with the NGS-derived contig sequences revealed high molecular diversity in AcV-1 populations, with the highest sequence variation occurring at ORF1a, ORF2, and ORF3, and the available variants clustered into three phylogenetic clades. For the first time, our study revealed different domain compositions in the viral ORF1a and molecular recombination events among AcV-1 variants. Specific reverse transcriptase–polymerase chain reaction assays disclosed the presence of AcV-1 in plants of four kiwifruit species and unknown Actinidia spp. in seven provinces and one city.


2018 ◽  
Author(s):  
Maarten P.M. Vanhove ◽  
Andrew G. Briscoe ◽  
Michiel W.P. Jorissen ◽  
D. Tim J. Littlewood ◽  
Tine Huyse

AbstractBackgroundMonogenean flatworms are the main ectoparasites of fishes. Representatives of the species-rich families Gyrodactylidae and Dactylogyridae, especially those infecting cichlid fishes and clariid catfishes, are important parasites in African aquaculture, even more so due to the massive anthropogenic translocation of their hosts worldwide. Several questions on their evolution, such as the phylogenetic position of Macrogyrodactylus and the highly speciose Gyrodactylus, remain unresolved with available molecular markers. Also, diagnostics and population-level research would benefit from the development of higher-resolution genetic markers. We aim to advance genetic work on African monogeneans by providing mitogenomic data of four species (two each belonging to the Gyrodactylidae and Dactylogyridae), and analysing their gene sequences and gene order from a phylogenetic perspective.ResultsBased on Illumina technology, the first four mitochondrial genomes of African monogeneans were assembled and annotated for the cichlid parasites Gyrodactylus nyanzae, Cichlidogyrus halli, Cichlidogyrus mbirizei (near-complete mitogenome) and the catfish parasite Macrogyrodactylus karibae (near-complete mitogenome). The start codon TTG is new for Gyrodactylus and for the Dactylogyridae, as is the incomplete stop codon TA for the Dactylogyridae. The most variable markers are nad genes and these are under relaxed selection. Especially nad2 is promising for primer development. Gene order was identical for protein-coding genes and differed between the African representatives of these families only in a tRNA gene transposition. A mitochondrial phylogeny based on an alignment of nearly 12,500 bp including 12 protein-coding and two ribosomal RNA genes confirms that the Neotropical oviparous Aglaiogyrodactylus forficulatus takes a sister group position with respect to the other gyrodactylids, rather than the supposedly ‘primitive’ African Macrogyrodactylus. Inclusion of the African Gyrodactylus nyanzae confirms the paraphyly of Gyrodactylus. The position of the African dactylogyrid Cichlidogyrus is unresolved, although gene order suggests it is closely related to marine ancyrocephalines.ConclusionsThe amount of mitogenomic data available for gyrodactylids and dactylogyrids is increased by roughly one-third. Our study underscores the potential of mitochondrial genes and gene order in flatworm phylogenetics, and of next-generation sequencing for marker development for these non-model helminths for which few primers are available while they constitute a risk to tropical aquaculture.


Author(s):  
Altuğ Koç ◽  
Elçin Bora ◽  
Tayfun Cinleti ◽  
Gizem Yıldız ◽  
Meral Torun Bayram ◽  
...  

2020 ◽  
Vol 16 ◽  
Author(s):  
Pelin Telkoparan-Akillilar ◽  
Dilek Cevik

Background: Numerous sequencing techniques have been progressed since the 1960s with the rapid development of molecular biology studies focusing on DNA and RNA. Methods: a great number of articles, book chapters, websites are reviewed, and the studies covering NGS history, technology and applications to cancer therapy are included in the present article. Results: High throughput next-generation sequencing (NGS) technologies offer many advantages over classical Sanger sequencing with decreasing cost per base and increasing sequencing efficiency. NGS technologies are combined with bioinformatics software to sequence genomes to be used in diagnostics, transcriptomics, epidemiologic and clinical trials in biomedical sciences. The NGS technology has also been successfully used in drug discovery for the treatment of different cancer types. Conclusion: This review focuses on current and potential applications of NGS in various stages of drug discovery process, from target identification through to personalized medicine.


Diagnostics ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 962
Author(s):  
Dario de Biase ◽  
Matteo Fassan ◽  
Umberto Malapelle

Next-Generation Sequencing (NGS) allows for the sequencing of multiple genes at a very high depth of coverage [...]


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