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Genetic characterization of porcine circovirus-2 field isolates from PMWS pigs
Young S. Lyoo,YoungS.Lyoo 대한수의학회 2002 Journal of Veterinary Science Vol.3 No.1
PMWS is a new emerging disease in swine herdsworldwide. Field isolates of PCV-2, a putative majorcausative agent of PMWS, were isolated and geneticalycharacterized. Viral genome of two field isolates(PC201DJ and PC201SS) from pigs showing typicalPMWS was equenced. The nucleotide sequence homologywith other PCV-2 isolates was ranging from 95% to99% in complete viral genomic sequence. The highlywas identical to that of other PCV-2 isolates. Todetermine the genetic heterogeneity of PCV-2 isolates,t h e p h y l o g e n e t i c t r e e b a s e d o n t h e c o m p l e t e g e n o m eof PCV-2 isolates were constructed. Two PCV-2 fieldisolates were closely related to Canadian isolates ofPCV-2. PCV-2 isolated from field may have an originof North America nd is posibly originated fromimportation of breding stocks. The result indicatesthat although the genome of PCV-2 is relatively stablein general, minor genetic variations exist amongPCV-2 isolates from the diferent geographic locations.important implication for genetic characteristics ofPCV-2 infection. Thre major imunorelevant epitopesof capsid protein showed variations in amino acidsequences. Also, the variance of amino acid sequencein antigenic epitope xisted betwen two KoreanPCV-2 isolates.
Lyoo, Won-Seok,Noh, Seok-Kyun,Yeum, Jeong-Hyun,Kang, Gu-Chan,Ghim, Han-Do,Lee, Jinwon,Ji, Byung-Chul The Korean Fiber Society 2004 Fibers and polymers Vol.5 No.1
To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25℃ by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P/sub n/): 30,900-36,100) and of high yield (ultimate conversion of MMA into PMMA: 83-93 %) with diminishing heat generated during polymerization. The P/sub n/ and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.
Virulence of a novel reassortant canine H3N2 influenza virus in ferret, dog and mouse models
Lyoo, K. S.,Na, W.,Yeom, M.,Jeong, D. G.,Kim, C. U.,Kim, J. K.,Song, D. Springer Science + Business Media 2016 Archives of virology Vol.161 No.7
<P>An outbreak of a canine influenza virus (CIV) H3N2 reassortant derived from pandemic (pdm) H1N1 and CIV H3N2 in companion animals has underscored the urgent need to monitor CIV infections for potential zoonotic transmission of influenza viruses to humans. In this study, we assessed the virulence of a novel CIV H3N2 reassortant, VC378, which was obtained from a dog that was coinfected with pdm H1N1 and CIV H3N2, in ferrets, dogs, and mice. Significantly enhanced virulence of VC378 was demonstrated in mice, although the transmissibility and pathogenicity of VC378 were similar to those of classical H3N2 in ferrets and dogs. This is notable because mice inoculated with an equivalent dose of classical CIV H3N2 showed no clinical signs and no lethality. We found that the PA and NS gene segments of VC378 were introduced from pdmH1N1, and these genes included the amino acid substitutions PA-P224S and NS-I123V, which were previously found to be associated with increased virulence in mice. Thus, we speculate that the natural reassortment between pdm H1N1 and CIV H3N2 can confer virulence and that continuous surveillance is needed to monitor the evolution of CIV in companion animals.</P>
Lyoo, Young S.,Kim, Jin-hyun,Park, Choi-kyu The Korean Society of Veterinary Science 1999 大韓獸醫學會誌 Vol.39 No.2
New emerging post weaning multisystemic wasting syndrome (PMWS) threatening swine industry worldwide and investigation of the etiological agent is underway. The porcine circovirus (PCV) consistently identified from PMWS pigs and research result indicate that there is strong relationship between PCV and PMWS. Fauns with PMWS submitted pigs suffered from various PMWS typical signs and necropsy finding showed lymph node anomalies. The PCV DNA was amplified from inguinal lymph node collected from pigs with PMWS. PCV specific primers were successfully amplified PCV DNAs and were able to differentiate PCV type I and II. We have identified noble PCV virus with genetic variation. The virus showed insertion of the nucleic acid at the 5' of the genome but did not have PCR product with primer set corresponding to PCV type II virus.
Lyoo, Won Seok,Yeum, Jeong Hyun,Kwon, Oh Wook,Shin, Dong Soo,Han, Sung Soo,Kim, Byoung Chul,Jeon, Han Yong,Noh, Seok Kyun Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of applied polymer science Vol.102 No.4
<P>To identify the effect of blend ratios of syndiotacticity-rich poly(vinyl alcohol) (s-PVA)/atactic PVA (a-PVA) having similar number-average degrees of polymerization (P<SUB>n</SUB>)s of 4000 and degrees of saponification (DS)s of 99.9% on the rheological properties of s-PVA/a-PVA/water solutions, water-soluble s-PVA and a-PVA with different syndiotactic diad contents of 58.5 and 54.0%, respectively, were prepared by bulk copolymerization of vinyl pivalate and vinyl acetate (VAc) and solution polymerization of VAc, followed by saponifying the corresponding copoly(vinyl pivalate/vinyl acetate) and poly(vinyl acetate). The blend ratios played a significant role in rheological behavior. Over the frequency range of 10<SUP>−1</SUP>–10<SUP>2</SUP> rad/s, s-PVA/a-PVA blend solutions with larger s-PVA content show more shear thinning at similar (P<SUB>n</SUB>)s and (DS)s of polymer, suggesting that PVA molecules are more readily oriented as s-PVA content increases. Yield stress is higher for s-PVA/a-PVA blend solutions with larger s-PVA content at similar (P<SUB>n</SUB>)s and (DS)s of polymer. This indicates that more domains with internal order are produced at larger s-PVA content in s-PVA/a-PVA blend solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3934–3939, 2006</P>
Lyoo, Won Seok,Yeum, Jeong Hyun,Park, Joo Min,Kwak, Jin Woo,Kim, Joon Ho,Kim, Sam Soo,Ji, Byung Chul,Noh, Seok Kyun Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of applied polymer science Vol.96 No.4
<P>To precisely identify the effect of molecular weight of atactic poly(vinyl alcohol) (a-PVA) on the durability and polarizing efficiency (PE) of a-PVA/dye polarizing film, we prepared two (a-PVA)s with similar syndiotactic diad contents of 54.0%, degrees of saponification of 99.9%, and with different number-average degrees of polymerization [(P<SUB>n</SUB>)s] of 1700 and 4000, respectively. Through a series of experiments, it was found that molecular weight of a-PVA had a significant influence on the durability of a-PVA/dye film in heat and humidity conditions (relative humidity of 80% and temperature of 90°C). That is, both desorption of dye in a-PVA/dye film and transmittance of film decreased with increasing molecular weight of PVA. The change of PE (durability) of a-PVA/dye film in heat and humidity conditions was limited to about below 5%. The change of PE of PVA/dye film having P<SUB>n</SUB> of 4000 especially was limited to 1%, whereas that of a-PVA/iodine film with P<SUB>n</SUB> of 4000, was almost 80% under the same condition. Also, transmittance of the drawn a-PVA/dye film was far higher than that of the undrawn one. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 967–974, 2005</P>