Porcine endogenous retroviruses (PERVs) integrate into germline DNA as proviral genome that enables vertical transmission from parents to their offspring. The provirus usually survives as part of the host genome rather than as an infectious agent, but may become pathogenic if it crosses species barriers. Therefore, replication-competent PERV should be controlled through selective breeding or knockout technologies. Two microRNAs (miRNAs), dual LTR1 and LTR2, were selected to inhibit the expression of PERV in primary porcine kidney cells. The inhibition efficiency of the miRNAs was compared based on their inhibition of different PERV regions, specifically long terminal repeats (LTRs), gag, pol, and env. Gene expression was quantified using real-time polymerase chain reaction and the C-type reverse transcriptase (RT) activity was determined. The messenger RNA (mRNA) expression of the PERV LTR and env regions was determined in HeLa cells co-cultured with primary porcine kidney cells. The mRNA expression of the LTR, gag, pol, and env regions of PERV was dramatically inhibited by dual miRNA from 24 to 144 h after transfection, with the highest inhibition observed for the LTR and pol regions at 120 h. Additionally, the RT activity of PERV in the co-culture experiment of porcine and human cells was reduced by 84.4% at the sixth passage. The dual LTR 1+2 miRNA efficiently silences PERV in primary porcine kidney cells.
Coculture Techniques ; DNA ; Endogenous Retroviruses ; Gene Expression ; Genome ; HeLa Cells ; Humans ; Kidney ; MicroRNAs ; Parents ; Proviruses ; Real-Time Polymerase Chain Reaction ; RNA, Messenger ; RNA-Directed DNA Polymerase ; Selective Breeding ; Terminal Repeat Sequences ; Transfection

"Wu zhu yu", which is obtained from the dried unripe fruits of Tetradium ruticarpum (A. Jussieu) T. G. Hartley, has been used as a traditional Chinese medicine for treatment of headaches, abdominal colic, and hypertension for thousands of years. The present study was designed to assess the molecular genetic diversity among 25 collected accessions of T. ruticarpum (Wu zhu yu in Chinese) from different areas of China, based on inter-primer binding site (iPBS) markers and inter-simple sequence repeat (ISSR) markers. Thirteen ISSR primers generated 151 amplification bands, of which 130 were polymorphic. Out of 165 bands that were amplified using 10 iPBS primers, 152 were polymorphic. The iPBS markers displayed a higher proportion of polymorphic loci (PPL = 92.5%) than the ISSR markers (PPL = 84.9%). The results showed that T. ruticarpum possessed high loci polymorphism and genetic differentiation occurred in this plant. The combined data of iPBS and ISSR markers scored on 25 accessions produced five clusters that approximately matched the geographic distribution of the species. The results indicated that both iPBS and ISSR markers were reliable and effective tools for analyzing the genetic diversity in T. ruticarpum.
Base Sequence ; Binding Sites ; DNA Fingerprinting ; DNA Primers ; metabolism ; DNA, Plant ; genetics ; isolation & purification ; Evodia ; classification ; genetics ; Genetic Markers ; genetics ; Genetic Variation ; Interspersed Repetitive Sequences ; genetics ; Phylogeny ; Polymorphism, Genetic ; Random Amplified Polymorphic DNA Technique ; Terminal Repeat Sequences ; genetics

Long terminal repeat (LTR) retrotransposons are mobile DNA sequences that ubiquitously exist in eukaryotic genomes. They replicate themselves in the genome by copy-paste mechanism with RNA as medium. In higher plants, many active LTR retrotransposons have been applied to analyze molecular marker technology, genetic tagging, insertion mutation and gene function. Here, we systematically review the characteristics of plant active LTR retrotransposons, including their structures, copy numbers and distributions. We further analyzed the gag (group-specific antigen) and pol (polymerase) sequence features of different plants active LTR retrotransposons and the distribution patterns of the cis-acting elements in LTR regions. The results show that autonomous active LTR retrotransposons must contain LTR regions and code Gag, Pr, Int, Rt, Rh proteins. Both LTR regions are highly homologous with each other and contain many cis-regulatory elements; RVT and RNase_H1_RT domain are essential for Rt and Rh protein respectively. These results provide the basis for subsequent identification of plant active LTR retrotransposons and their functional analysis.
Genome, Plant ; Mutagenesis, Insertional ; Plants ; genetics ; Retroelements ; Terminal Repeat Sequences

AAV-ITR gene expression mini vector is a double-strand or single-strand DNA that only contains inverted terminal repeats of adeno-associated virus, cis-elements and gene of interest and does not contain any other foreign DNA sequences. We prepared Bac-ITR-EGFP and Bac-inrep. Spodoptera frugiperda cells were infected with Bac-ITR-EGFP (P3) and Bac-inrep (P3). Up to 100 μg of AAV-ITR-EGFP gene expression mini vectors were extracted from 2 x 10(7) cells of Sf9 72 h after infection. The gel electrophoresis analysis shows that most forms of AAV-ITR-EGFP gene expression mini vector were monomer and dimer. The mini vector expression efficacy was examined in vitro with HEK 293T cells. The EGFP expression was observed at 24 h after transfection, and the positive ratio reached 65% at 48 h after transfection.
Animals ; Baculoviridae ; DNA, Single-Stranded ; Dependovirus ; Gene Expression ; Genetic Vectors ; HEK293 Cells ; Humans ; Sf9 Cells ; Terminal Repeat Sequences ; Transfection

To obtain the genome sequence of human bocavirus 2 (HBoV2), different regions of HBoV2 genome were amplified through PCR in fecal specimens which had been identified as single-positive for HBoV2 in 2010. A genome sequence of HBoV2 (HBoV2-NC, 5444 bp) was obtained after sequence assembly. The phylogenetic analysis showed that HBoV2-NC had the closest evolutionary relationship with HBoV2 Lanzhou strain. The predication of inverted terminal repeats of HBoV2-NC by DINAMelt showed that inverted terminal repeats were contained in HBoV2-NC 5' terminal, which had the typical stem-loop structure in other parvoviruses. Finally, some flanking sequences of HBoV2-NC were amplified by linker-PCR.
Base Sequence ; Gene Amplification ; Genome, Viral ; Human bocavirus ; chemistry ; classification ; genetics ; Humans ; Molecular Sequence Data ; Nucleic Acid Conformation ; Parvoviridae Infections ; virology ; Phylogeny ; RNA, Viral ; chemistry ; genetics ; Terminal Repeat Sequences

Approximately 45% of the human genome is comprised of transposable elements (TEs). Results from the Human Genome Project have emphasized the biological importance of TEs. Many studies have revealed that TEs are not simply "junk" DNA, but rather, they play various roles in processes, including genome evolution, gene expression regulation, genetic instability, and cancer disposition. The effects of TE insertion in the genome varies from negligible to disease conditions. For the past two decades, many studies have shown that TEs are the causative factors of various genetic disorders and cancer. TEs are a subject of interest worldwide, not only in terms of their clinical aspects but also in basic research, such as evolutionary tracking. Although active TEs contribute to genetic instability and disease states, non-long terminal repeat transposons are well studied, and their roles in these processes have been confirmed. In this review, we will give an overview of the importance of TEs in studying genome evolution and genetic instability, and we suggest that further in-depth studies on the mechanisms related to these phenomena will be useful for both evolutionary tracking and clinical diagnostics.
DNA ; DNA Transposable Elements* ; Gene Expression ; Gene Expression Regulation ; Genome* ; Genome, Human ; Human Genome Project ; Humans ; Terminal Repeat Sequences

Although the number of protein-coding genes is not highly variable between plant taxa, the DNA content in their genomes is highly variable, by as much as 2,056-fold from a 1C amount of 0.0648 pg to 132.5 pg. The mean 1C-value in plants is 2.4 pg, and genome size expansion/contraction is lineage-specific in plant taxonomy. Transposable element fractions in plant genomes are also variable, as low as ~3% in small genomes and as high as ~85% in large genomes, indicating that genome size is a linear function of transposable element content. Of the 2 classes of transposable elements, the dynamics of class 1 long terminal repeat (LTR) retrotransposons is a major contributor to the 1C value differences among plants. The activity of LTR retrotransposons is under the control of epigenetic suppressing mechanisms. Also, genome-purging mechanisms have been adopted to counter-balance the genome size amplification. With a wealth of information on whole-genome sequences in plant genomes, it was revealed that several genome-purging mechanisms have been employed, depending on plant taxa. Two genera, Lilium and Fritillaria, are known to have large genomes in angiosperms. There were twice times of concerted genome size evolutions in the family Liliaceae during the divergence of the current genera in Liliaceae. In addition to the LTR retrotransposons, non-LTR retrotransposons and satellite DNAs contributed to the huge genomes in the two genera by possible failure of genome counter-balancing mechanisms.
Angiosperms ; Classification ; DNA ; DNA Transposable Elements* ; DNA, Satellite ; Epigenomics ; Fritillaria ; Genome ; Genome Size* ; Genome, Plant ; Humans ; Liliaceae ; Lilium ; Plants ; Retroelements ; Terminal Repeat Sequences

Vpr, an auxiliary protein of HIV-1(Human immunodeficiency virus type 1), exerts important functions to promote viral replication and AIDS progression. In this study, we performed a yeast two-hybrid screening assay using human cDNA library to further investigate the molecular mechanism of various functions of Vpr RelB, a key protein in NF-kappaB signaling pathway, was identified as a Vpr interaction protein by co-immunoprecipitation. Further investigations indicated that RelB not only promoted the Vpr-mediated activation of NF-kappaB reporter gene, but also enhanced the transactivation of HIV LTR. Moreover, the results showed that RelB promoted Vpr-induced cell cycle G2/M arrest. Collectively, these results indicated that RelB might interact with Vpr and regulate its transcriptional activation and cell cycle arrest.
Cell Cycle Checkpoints ; Cell Division ; G2 Phase ; HIV Long Terminal Repeat ; HeLa Cells ; Humans ; NF-kappa B ; genetics ; Transcription Factor RelB ; physiology ; Transcriptional Activation ; vpr Gene Products, Human Immunodeficiency Virus ; physiology

OBJECTIVETo evaluate the anti-viral effects of a plasmid expressing an inverted-repeat RNA targeting dengue virus type-2 (DENV-2) pre-membrane (prM) gene.

METHODSuckling mice were inoculated with live DENV-2 in the brain. The total RNA was extracted from the brain tissue of the infected mice, and the prM gene fragments were amplified by RT-PCR and then subcloned into XhoI/EcoR I of the pcDNA3.1(+) plasmid in antisense orientation to construct the plasmid pcDNA-asprM. DENV-2 prM sequences were also subcloned into pMD18-T-vector in sense orientation to construct the plasmid pMD18-T- prM. pcDNA-irRNA was constructed by inserting in sense orientation the prM fragment isolated from pMD18-T-prM into the NheI/Kpn I of pcDNA-asprM. The plasmid pcDNA-irRNA was transfected into BHK-21 cells and the anti-viral effects were analyzed by semi-quantitative PCR and real-time PCR.

RESULTSTransfection with the plasmid pcDNA-irRNA caused a reduction of NS3 mRNA expression level by 28% in BHK-21 cells following a 96-h challenge with DENV-2 as compared to the cells without plasmid transfection (positive control). The viral copies in pcDNA-irRNA-transfected cells was 1.44-fold lower than those in the positive control cells following a 72-h virus challenge, and the mRNA expression levels of NS1 were also significantly lower in the transfected cells at 96 h after viral challenge (P<0.05) as shown by real-time quantitative PCR.

CONCLUSIONThe inverted-repeat RNA for DENV-2 prM gene silencing can suppress DENV-2 replication in BHK-21 cells, which provides a basis for developing dengue virus gene vaccine.

Animals ; Base Sequence ; Cells, Cultured ; Cricetinae ; Dengue Virus ; physiology ; Gene Silencing ; Mice ; Mice, Inbred Strains ; RNA, Viral ; genetics ; Terminal Repeat Sequences ; Viral Envelope Proteins ; genetics ; Virus Replication ; genetics

Adeno-associated virus (AAV) has many advantages for gene therapy over other vector systems. However, after the production of recombinant AAV (Raav) vectors, the biological titration of rAAV stocks is still cumbersome. Different investigators used laboratory-specific methods or internal reference standards that may limit preclinical and clinical applications. The inverted terminal repeats (ITR) sequences are the only cis-regulated viral elements required for rAAV packaging and remain within viral vector genomes. ITR is the excellent target sequences for qPCR quantification of rAAV titer. In this study, we developed a novel qPCR strategy to quantify rAAVs' vector genome titer via targeting the ITR2 or ITR2-CMV element. In conclusion, the method is fast and accurate for the titration of rAAV2-derived vector genomes. It will promote the standardization of rAAV titration in the future.
Dependovirus ; classification ; genetics ; Genetic Vectors ; genetics ; Genome, Viral ; genetics ; Polymerase Chain Reaction ; methods ; Recombination, Genetic ; Serotyping ; Terminal Repeat Sequences ; genetics ; Transduction, Genetic