• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.627-633
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• 1996

To analyze the genomic diversity of transmissible gastroenteritis virus (TGEV), the N-terminal half of the spike (S) glycoprotein gene and nonstructural protein gene (open reading frames 3 and 3-1) were amplified by reverse transcriptase reaction and polymerase chain reaction (RT-PCR), and analyzed using restriction fragment length polymorphism (RFLP) patterns of the amplified DNA. In this study, TGEV Miller (M6) and Purdue (P115) strains were used as reference strains, and two vaccine strains (MSV and STC3) and four Korea isolates (P44, VRI-WP, VRI-41, and VRI-48) were analyzed. All TGEV strains were amplified with three TGEV primer pairs. Although there was some exception in RFLP analysis, this method differentiated TGEV strains into following groups : Miller group (M6 and MSV), Purdue group (PUS, STC3, P44, VRI-WP, VRI-41, and VRI-48). Using Sau3AI and SspI, VRI-48 was differentiated from the Miller and Purdue type viruses. The RT/PCR in conjuction with RFLP analysis was a rapid and valuable tool for differentiating several strains of TGEV. This study revealed the occurences of distinct difference in genome of TGEV strains.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.319-327
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• 1998

The nucleotide sequences of spike (S) glycoprotein containing antigenic sites A and D of TGEV isolated in Korea were determined and compared with published sequences for TGEVs. The TGEV 133 and DAE5 strains had 97.40% nucleotide sequence similarity. The overall nucleotide sequence similarity of the 133 and DAE5 strains compared with other TGEV strains was between 96.86% and 99.15%. The similarity of the predicted amino acid sequence of the 133 and DAE5 strains was 94.93%. The TGEV 133 and DAE5 strains had 94.93-98.61% amino acid similarity with published sequences of other TGEV strains. The sequences of amino acid codons in the antigenic sites A and D were identical among all the viruses although there were several nucleotide changes in region containing antigenic sites A and D of Korean TGEV isolates. By phylogenetic analysis of the sequences, two Korean isolates 133 and DAE5 seemed to be derived from different lineages. These studies showed that a distinct difference in genome exists among TGEV field strains isolated in Korea.

• IMMUNE NETWORK
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• v.20 no.5
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• pp.41.1-41.11
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• 2020

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is a positive-sense single-stranded RNA (+ssRNA) that causes coronavirus disease 2019 (COVID-19). The viral genome encodes twelve genes for viral replication and infection. The third open reading frame is the spike (S) gene that encodes for the spike glycoprotein interacting with specific cell surface receptor - angiotensin converting enzyme 2 (ACE2) - on the host cell membrane. Most recent studies identified a single point mutation in S gene. A single point mutation in S gene leading to an amino acid substitution at codon 614 from an aspartic acid 614 into glycine (D614G) resulted in greater infectivity compared to the wild type SARS-CoV2. We were interested in investigating the mutation region of S gene of SARS-CoV2 from Korean COVID-19 patients. New mutation sites were found in the critical receptor binding domain (RBD) of S gene, which is adjacent to the aforementioned D614G mutation residue. This specific sequence data demonstrated the active progression of SARS-CoV2 by mutations in the RBD of S gene. The sequence information of new mutations is critical to the development of recombinant SARS-CoV2 spike antigens, which may be required to improve and advance the strategy against a wide range of possible SARS-CoV2 mutations.

• Korean Journal of Veterinary Service
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• v.44 no.2
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• pp.73-83
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• 2021

Although many swine farms continuously vaccinated to sow to prevent Porcine epidemic diarrhea(PED), PED has occurred annually in swine herds in Jeonbuk province, Korea. In the present study, the small intestine and feces samples from 17 farms where severe watery diarrhea and death of newborn piglets occurred in 2019 were collected, amplified by RT-PCR and determined the complete nucleotide sequences of the spike (S) glycoprotein genes of nine Jeonbuk PEDV isolates. The spike (S) glycoprotein is an important determinant for molecular characterization and genetic relationship of PEDV. These nine complete S gene isolates were compared with other PEDV reference strains to identify the molecular diversity, phylogenetic relationships and antigenicity analysis. 9 field strains share 98.5~100% homologies with each other at the nucleotide sequence level and 97.3~100% homologies with each other at the amino acid level. The nine Jeonbuk PEDV isolates were classified into G2b group including a genetic specific signal, S-indels (insertion and deletion of S gene). In addition, comparisons the neutralizing epitopes of S gene between 9 field strains and domestic vaccine strains of Korea mutated 12-15 amino acids with SM-98-1 (G1a group) and mutated 0-3 amino acids with QIAP1401 (G2b group). Therefore, the development of G2b-based live vaccines will have to be expedited to ensure effective prevention of endemic PED in Korea. In addition, we will need to be prepared with periodic updates of preventive vaccines based on the PEDV variants for the re-emergence of a virulent strain.

• Korean Journal of Veterinary Service
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• v.39 no.4
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• pp.259-266
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• 2016

Porcine epidemic diarrhea virus (PEDV) causes an acute and lethal watery diarrhea in piglets that is great economic losses to the swine country worldwide. The spike (S) glycoprotein is an important determinant for PEDV biological properties. In the present study, we determined the full-length S gene sequences of five Chung-nam PEDV field isolates collected in 2016. The S gene was amplified by RT-PCR, purificated, sequenced, analyzed and then compared with published sequences of other PEDV strains. 5 field strains share 98.5%~99.9% homologies with each other at the nucleotide sequence level and 96.7%~99.9% homologies with each other at the amino acids sequence level. Most field strains have nucleotide insertions, deletions and mutation regions, and show lower homologies (93.1~93.8%) with classical and vaccine strains, however higher homologies (99.1%~99.5%) with US PEDV isolates in 2013. By phylogenetic tree analysis based on nucleotide sequence, five PEDV field isolates were clustered into Genogroup 2b but differ genetically from the vaccine strains (SM-98 and DR-13).

• Korean Journal of Veterinary Service
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• v.38 no.1
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• pp.51-56
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• 2015

Infectious bronchitis virus (IBV) causes an acute and highly contagious viral disease of chicken that is great economic losses to the poultry industry worldwide. Among the IBV structural proteins, the high rate spike glycoprotein S1 gene mutation and antigenic variant strains have been reported in many countries. During the years 2012~2014, 10 IBV strains were isolated from infected chicken farms distributed in provinces of Jeonbuk. Analysis of the S1 gene sequences amplified from 10 isolated strains with QX strains showed nucleotide homologies ranging from 96.5 to 95.4%. Phylogenetic analysis revealed that all strains were clustered into QX-like groups. This study suggests that QX-like IBVs are circulating in commercial chicken farms in Jeonbuk. Therefore, the continuing survellance is significantly important for prevention and control of BIV infection.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.304-313
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• 1998

Sixteen Korean field transmissible gastroenteritis viruses (TGEVs) were isolated using swine testicular cell (STC) and the genomic diversity of them was analyzed. All TGEV isolates produced a typical cytopathic effect in STC and were confirmed as TGEV by immunofluorescence assay using monoclonal antibody against TGEV and PCR using TGEV specific primers. RNAs from TGEV field isolates and vaccine TGEV were extracted and amplified by RT and PCR. The RT-PCR products were digested with selected restriction enzymes and analyzed RFLP patterns. The N-terminal end region of S gene and ORF 3 and 3-1 genes of TGEV amplified by TGEV specific primer pairs seemed to be conserved. Most specific variations were detected in S gene amplified by TGEV 4/6 primer pairs which includes antigenic sites A and D. When the PCR products were treated with Sau3AI and Ssp I, Bvac(vaccine strain), field isolates 133 and 347 were differentiated from Miller and Purdue types. In the case of D5 field isolates, it was classified into Purdue type by Sau 3AI but classified into independent TGEV by Ssp I. Two different TGEV strains from D2 sample were confirmed by plaque purification and RT-PCR-RFLP analysis. To investigate the change occurring in TGEV genome after serial passage, the TGEV P44 strain was passaged through STC. There were specific changes in S gene and a large deletion was observed in ORF 3 and 3-1 genes. These studies showed that a distinct difference in genome exists among TGEV field isolates.

• Korean Journal of Veterinary Service
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• v.25 no.1
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• pp.87-96
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• 2002

In this study, we wanted to determine if the respirotropic JMK strain of infectious bronchitis virus(IBV), which has a spike glycoprotein gene that is 99% similar to the nephropathogenic Gray strain of IBV, could adapt and cause lesions in the kidney following intracloacal passage in chickens. Two day old specific pathogen free(SPF) cchickens were infected with Gray and JMK strains by the intraocular and cloacal route. Several tissue samples were collected at various times. Viruses were recovered from more tissues and earlier in the infection from chickens infected cloacally than chickens infected intraocularly. Virus was isolated from the kidney of chickens infected with Gray by the intraocular route and JMK by the intracloacal route, but not from chicken given JMK the intraocular route. Histopathologically, interstitial nephritis was observed in Gray infected chickens. However, viral RNA or antigen were not detected in the kidney by in situ hybridization and immunohistochemistry. We further passaged the JMK strain ten times in two day old SPF chickens using cloacal inoculation. We examined the virus titer and histopathological change in the kidney at each passage level. The amount of virus recovered from the kidney was stable throughout this serial passage and the passaged virus did not caused renal damage. Further, virus could not be isolated from the kidney when chickens were infected with the passaged virus by the intraocular route. We conclude that the JMK strain has a strict upper respiratory tract tropism since cloacal passage did not produce nephrotropism or nephropathogenicity.