• 대한바이러스학회지
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• 제30권2호
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• pp.131-139
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• 2000

Bovine leukemia virus (BLV) is an etiological agent of chronic diseases in cows worldwide. The BLV is one of retroviruses that contain a multi-functional enzyme, reverse transcriptase produced from the pol gene in its genome. We have sequenced some regions in the pol gene of BLV proviruses found in the Southern province of Korea from samples that turned out to be BL V positives by a PCR analysis. On the 5' side of the BLV pol gene (polymerase region), it was found that there were four leucines located at every 7 amino acids. They can form a leucine zipper motif that was not same as the pol gene of Japanese BLV isolate. The sequencing result of the proviral pol gene in Korean-type BLV also revealed some mutations leading to amino acid changes such as $CCT(Pro){\to}CTC(Leu)$, $AAT(Asn){\to}AAA(Lys)$, and non-sensible variations i.e., $TCT(Ser){\to}TCC(Ser)$, $ATT(Ile){\to}ATC(I1e)$ and $ACG(Thr){\to}ACA(Thr)$. On the 3' side of the pol gene (integrase region), some nucleotide sequences were mutated and led to amino acid changes. Among them, a mutation, $GAA(Glu){\to}GAC(Asp)$ occurred in many Korean-type BLV proviruses was very interesting because the amino acid was regarded as one of the most conserved amino acids in the retroviral integrase. It was also notable that the mutation on any leucine residue did not occur, in spite of its frequent appearance.

• Molecules and Cells
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• 제28권2호
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• pp.99-103
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• 2009

Human endogenous retroviruses (HERVs) have been implicated in the pathogenesis of several human diseases as multi-copy members in the human genome. Their gene expression profiling could provide us with important insights into the pathogenic relationship between HERVs and cancer. In this study, we have evaluated the genomic structure and quantitatively determined the expression patterns in the env gene of a variety of HERV family members located on six specific loci by the RetroTector 10 program, as well as real-time RT-PCR amplification. The env gene transcripts evidenced significant differences in the human tumor/normal adjacent tissues (colon, liver, uterus, lung and testis). As compared to the adjacent normal tissues, high levels of expression were noted in testis tumor tissues for HERV-K, in liver and lung tumor tissues for HERV-R, in liver, lung, and testis tumor tissues for HERV-H, and in colon and liver tumor tissues for HERV-P. These data warrant further studies with larger groups of patients to develop biomarkers for specific human cancers.

• Journal of Microbiology and Biotechnology
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• 제24권4호
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• pp.577-583
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• 2014

Three major classes of retroviral restriction factors (APOBEC3G, Tetherin, and TRIM5${\alpha}$) have been identified in mammals. Restriction factors are cellular proteins that are able to limit viral replication by targeting specific steps of the viral life cycle. To evaluate which restriction factor is the most effective to inhibit the replication of porcine endogenous retroviruses (PERVs), the antiviral activity of each restriction factor was compared. In pseudotype assay, the antiviral activity of human tetherin against PERV pseudotype was slightly weaker than that of human APOBEC3G (hA3G). A combination of tetherin and hA3G was more potent than each individual restriction factor. We questioned whether a combination of tetherin and hA3G could also inhibit the spreading replication of PERV. In agreement with the pseudotype assay, two restriction factors inhibit infectious PERV replication in a spreading infection. In this study, hA3G could strongly inhibit the replication of PERV, but tetherin modestly restricted it. Based on these results, we concluded that a combination of tetherin and hA3G is the most effective way to restrict PERV. A combination of different restriction factors will encourage the development of a new approach to treat retroviral disease.

• Molecules and Cells
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• 제22권3호
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• pp.360-363
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• 2006

Human endogenous retroviruses (HERVs) contribute to various kinds of genomic instability via rearrangement and retrotransposition events. In the present study the formation of a new human-specific solo-LTR belonging to the HERV-H family (AP001667; chromosome 21q21) was detected by a comparative analysis of human chromosome 21 and chimpanzee chromosome 22. The solo-LTR was formed as a result of an equal homologous recombination excision event. Several evolutionary processes have occurred at this locus during primate evolution, indicating that mammalian-wide interspersed repeat (MIR) and full-length HERV-H elements integrated into hominoid genomes after the divergence of Old World monkeys and hominoids, and that the solo-LTR element was created by recombination excision of the HERV-H only in the human genome.

• 식물조직배양학회지
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• 제22권5호
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• pp.241-260
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• 1995

Transposons, present in the genomes of all living organisms, are genetic element that can change positions, or transpose, within the genome. Most genomes contain several kinds of transposable elements and the molecular details of the mechanisms by which these transposons move have recently been uncovered in many families of transposable elements. Transposition is brought about by an enzyme known as transposaese encoded by the autonomous transposon itself, but, in the unautonomous transposon lacking the gene encoding the transposase, movement occurs only at the presence of the enzyme encoded by the autonomous one. There are two types of transposition events, conservative and replicative transposition. In the former the transposon moves without replication, both strands of the DNA moving together from one place to the other while in the latter the transposition frequently involves DNA replication, so one copy of transposon remains at its original site as another copy insole to a new site. The insertion of transposon into a gene can prevent it expression whereas excision from the gene may restore the ability of the gene to be expressed. There are marked similarities between transposons and certain viruses having single stranded Plus (+) RNA genomes. Retrotransposons, which differ from the ordinary transposons in that they transpose via an RNA-intermediate, behave much like retroviruses and have a structure of integrated retrovial DNA when they are inserted to a new target site. An insertional mutagenesis called transposon-tagging is now being used in a number of plant species to isolate genes involved in developmental and metabolic processes which have been proven difficult to approach by the traditional methods. Attempts to device a transposon-tagging system based on the maize Ac for use in heterologous species have been made by many research workers.

• 대한의생명과학회지
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• 제10권1호
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• pp.55-63
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• 2004

Bovine leukemia virus (BLV) is a causative agent for lymphoma disease in cattle including cows worldwide. BLV shares similar virion structure and characteristics with other retroviruses. The pol gene of the BLV genome produced reverse transcriptase (RT) and integrase (IN) for important roles for BLV genome integration into host cell chromosomes that is known to be coded in the 3' side of the BLV pol gene (one third portion). In this study, we have sequenced 978 bp in the 3' side of the BLV pol gene from BLV 10C3 in order to determine the BLV IN region of it. And we compared it to the nucleotide sequences of an Australian BLV isolate. As a result, nucleotide sequences of the IN region of the Korean-type BLV pol gene were mutated at a rate of 3.7%. We can confirm that the typical mutations are such as Arg (AGG) $\rightarrow$ Lys (AAG), Thr (ACG) $\rightarrow$ Met (ATG), Ile (ATT) $\rightarrow$ Val (GTT), Asn (ACC) $\rightarrow$ His (CAC), Phe (TTT) $\rightarrow$ Leu (TTG) and Asn (ACC) $\rightarrow$ Asp (GAC). From the analysis of the sequencing data, we were able to determine the zinc-finger-like "HHCC" motif in the amino terminus of BLV IN, that was H-$X_3$-H-$X_{25}-C-X_2$-C. It was also found the DD35E motif in the IN catalytic domain as D-$X_{56}$-D-$X_{35}$-E. It fits very well to the consensus sequences of retroviral IN as well as HHCC motif.

• Genomics & Informatics
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• 제3권4호
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• pp.133-141
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• 2005

Most of the endogenous retroviral genes integrated into the primate genome after the split of New World monkeys in the Oligocene era, approximately 33 million years ago. Because they can change the structure of adjacent genes and move between and within chromosomes they may play important roles in evolutionas well as in many kinds of disease and the creation of genetic polymorphism. Comparative analysis of HERVs (human endogenous retroviruses) and their LTR (long terminal repeat) elements in the primate genomes will help us to understand the possible impact of HERV elements in the evolution and phylogeny of primates. For example, HERV-K LTR and SINE-R elements have been identified that have been subject to recent change in the course of primate evolution. They are specific elements to the human genome and could be related to biological function. The HERV-M element is related to the superfamily of HERV-K and is integrated into the periphilin gene as the truncated form, 5'LTR-gag-pol-3'LTR. PCR and RT-PCR approaches indicated that the insertion of various retrotransposable elements in a common ancestor genome may make different transcript variants in different primate species. Examination of the HERV-W elementrevealed that env fragments were detected on human chromosomes 1, 3-7, 12, 14, 17, 20, and X, whilst the pol fragments were detected on human chromosomes 2-8, 10-15, 20, 21, X, and Y. Bioinformatic blast search showed that almost full-length of the HERV-W family was identified on human chromosomes 1-8, 11-15, 17, 18, 21, and X. Expression analysis of HERV-W genes (gag, pol, and env) in human tissues by RT-PCR indicated that gag and pol were expressed in specific tissues, whilst env was constituitively expressed in all tissues examined. DNA sequence based phylogenetic analysis indicated that the gag, pol and env genes have evolved independently during primate evolution. It will thus be of considerable interest to expand the current HERV gene information of various primates and disease tissues.

• BMB Reports
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• 제54권7호
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• pp.368-373
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• 2021

The vertebrate genome contains an endogenous retrovirus that has been inherited from the past millions of years. Although approximately 8% of human chromosomal DNA consists of sequences derived from human endogenous retrovirus (HERV) fragments, most of the HERVs are currently inactive and noninfectious due to recombination, deletions, and mutations after insertion into the host genome. Several studies suggested that Human endogenous retroviruses (HERVs) factors are significantly related to certain cancers. However, only limited studies have been conducted to analyze the expression of HERV derived elements at protein levels in certain cancers. Herein, we analyzed the expression profiles of HERV-K envelope (Env) and HERV-R Env proteins in eleven different kinds of cancer tissues. Furthermore, the expression patterns of both protein and correlation with various clinical data in each tissue were analyzed. The expressions of both HERV-K Env and HERV-R Env protein were identified to be significantly high in most of the tumors compared with normal surrounding tissues. Correlations between HERV Env expressions and clinical investigations varied depending on the HERV types and cancers. Overall expression patterns of HERV-K Env and HERV-R Env proteins were different in every individual but a similar pattern of expressions was observed in the same individual. These results demonstrate the expression profiles of HERV-K and HERV-R Env proteins in various cancer tissues and provide a good reference for the association of endogenous retroviral Env proteins in the progression of various cancers. Furthermore, the results elucidate the relationship between HERV-Env expression and the clinical significance of certain cancers.

• Journal of Animal Science and Technology
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• 제49권3호
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• pp.405-414
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• 2007

돼지의 내인성 레트로 바이러스인 PERV의 존재는 돼지의 무균 사육을 통해서도 제거할 수 없으며, 장기 이식 시 인수 공통 감염의 위험성을 내포하고 있으므로, 이종 간 장기 이식 시 면역 거부 반응과 더불어 해결해야 할 가장 큰 문제점 중의 하나이다. 본 연구에서는 국내에서 사육되고 있는 Berkshire, Duroc, Landrace, Yorkshire 종을 비롯하여 국내 미니 돼지 및 제주도 토종 흑돼지에서 PERV의 존재 유무 및 종류에 대하여 확인 및 검출하는 중합효소 연쇄반응(PCR) 기반 기법을 확립하였다. 사용된 모든 공시 돼지의 genomic DNA로부터 PERV- A 및 PERV-B가 모두 검출되었으며, PERV-C의 경우 음성대조구인 PK15 세포에서의 결과와 비교했을 때, Duroc종에서 매우 낮은 양의 PCR 산물이, 국내 미니돼지와 제주 토종 흑돼지에서는 상대적으로 높은 양의 PCR 산물이 검출되었다. 또한 PERV-A와 PERV-B의 경우 특이적 primer와 제한효소 BamHI을 이용한 PCR- RFLP를 통하여 확인할 수 있었다. 본 연구의 PERV 검출법은 이종 간 장기 이식 시 PERV에 대한 안전 검정 및 PERV의 분류 방법으로서 활용가능할 것으로 사료된다.

• Reproductive and Developmental Biology
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• 제30권3호
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• pp.181-187
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• 2006

최근 돼지의 장기를 사람에게 이식하는 이종간 장기 이식에 관한 연구가 급속히 발전되고 있다. 그러나 돼지의 장기를 이식할 경우 가장 큰 문제점 중의 하나는 돼지 genome 내에 존재하는 내인성 레트로바이러스(porcine endogenous retrovirus; PERV)가 인간에게 그대로 전이될 수 있다는 것이다. 이에 대한 대안으로 최근 활발히 연구되고 있는 RNA 간섭을 통한 PERV RNA의 발현을 최대한 억제하는 방법이 제안되고 있는데, RNA 간섭(RNA interference)은 double-standard RNA(dsRNA)가 상보적인 표적 mRNA를 분해하여 결과적으로 표적 단백질의 발현을 특이적으로 억제하는 현상을 의미한다. 본 연구에서는 PERV에 대한 RNA 간섭 현상을 일으키는 shRNA 유전자를 레트로바이러스 벡터를 이용하여 돼지세포에 RNA)가 상보적인 표적 mRNA를 분해하여 결과적으로 표적 단백질의 발현을 특이적으로 억제하는 현상을 의미하다. 도입한 후 PERV의 발현율 감소 여부를 조사하였다. 그 결과, gag-pol 유전자와 env 유전자 발현은 각각 대조군 세포의 4%와 10% 정도로 억제되었다. 한편, virus 입자의 생산에서 gag-pol 유전자는 대조군 세포에 비해 300배 이상 억제되었으며, env 유전자에서는 20만 배 이상 억제되었다. 이상의 결과를 미루어 볼 때 형질 전환 돼지를 이용한 이종 장기 이식에 있어서 RNA 간섭 현상을 이용한 PERV의 발현을 억제하는 시도는 생물학적안전성을 크게 증가시킬 수 있을 것으로 사료된다.