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Papers by BYOUNG JOO SEO

This study explored the optimal culture conditions for maximizing shiga toxin production in Stx2e... more This study explored the optimal culture conditions for maximizing shiga toxin production in Stx2e-producing Escherichia coli (STEC) 150229, isolated from porcine edema disease (ED), with the goal of preparing a Stx2e toxoid vaccine candidate. High cytotoxicity was observed for this strain [tissue culture cytotoxic dose 50% (10 4 TCCD 50 /100 μl)] from 48 h after incubation. Stx2e was overexpressed by transforming pStx2e A into STEC 150229, resulting in the production of recombinant Stx2e A/B complex combined with intrinsic Stx2e B. The enhanced production of Stx2e was evaluated based on the level of cytotoxicity against Vero cells. The highest cytotoxicity (10 5 TCCD 50 /100 μl) was observed with the samples of recombinant Stx2e A/B complex eluted with 500 mM imidazole at 48 h of incubation. In conclusion, the recombinant Stx2e A protein forms an active protein complex with the intrinsic Stx2e B component from STEC 150229, producing high levels of shiga toxin.

Additional file 1 of Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

Additional file 1. The identified genes of the C. novyi isolate.

Comparison of the pathogenicity of porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in pregnant sows

Archives of Virology, 2022

To date, few studies related to the evaluation of the pathogenicity of different PRRSV isolates u... more To date, few studies related to the evaluation of the pathogenicity of different PRRSV isolates using a reproductive model have been undertaken, and the main focus has remained on respiratory models using young pigs. This study aimed to evaluate the pathogenicity of two PRRSV-1 isolates (D40 and CBNU0495) and two PRRSV-2 isolates (K07-2273 and K08-1054) in a reproductive model. Pregnant sows were experimentally infected with PRRSV at gestational day 93 or used as an uninfected negative control. Sera were collected at 0, 3, 7, 14, and 19 days post-challenge (dpc) for virological and serological assays. At 19 dpc, all sows were euthanized, and their fetuses were recovered by performing cesarean section and immediately euthanized for sample collection. Here, compared to the other isolates, the CBNU0495 isolate replicated most efficiently in the pregnant sows, and K07-2273 produced the highest rate of reproductive failure even though it did not replicate as efficiently as the other isolates in sows and fetuses, indicating that vertical transmission and reproductive failure due to PRRSV infection do not have any significant correlation with the viral loads in samples from sows and fetuses. Similarly, the viral loads and the histopathological lesions did not show any correlation with each other, as the PRRSV-2-infected groups displayed more prominent and frequent histopathological lesions with lower viral loads than the PRRSV-1-infected groups. However, viral loads in the myometrium/endometrium might be related to the spreading of PRRSV in the fetuses, which affected the birth weight of live fetuses. This study contributes to a better understanding of the pathogenicity of the most prevalent Korean PRRSVs in a reproductive model.

Differences in Manufacturing Process and Quality between Cheonggukjang for Use in the Raw and Cheonggukjang for Stew

Food Science and Biotechnology, 2008

When cheonggukjang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-ter... more When cheonggukjang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-term fermentation for 14-18 hr appeared to be the optimal for the raw cheonggukjang to avoid the formation of a bitter taste and to contain a high concentration of free sugars, whereas a long-term fermentation for more than 4 days was the optimal for the cheonggukjang for stew in order to contain a high concentration of free amino and organic acids, which are responsible for sweet, savory, and bitter tastes present in stewed cheonggukjang. During activation of murine splenic T cells with phytohemagglutinin (PHA), the presence of either poly-γ-glutamic acid (γ-PGA) or partially hydrolyzed γ-PGA resulted in reduction in the level of interferon-γ production and enhancement in the level of interleukin-5 production, possibly due to suppression of Th1 activity and augmentation of Th2 activity. Taken together these results indicate that the raw cheonggukjang and the cheonggukjang for stew are diff...

Gut microbiome responses of pigs to a high dose of deoxynivalenol (DON) in feed

Single oral immunization of an attenuated Salmonella Gallinarium formulation consisting of equal quantities of strains secreting H9N2 hemagglutinin-HA1, HA2, and M2eCD154 induces significant protection against H9N2 and partial protection against Salmonella Gallinarium challenge in chickens

Veterinary Immunology and Immunopathology, 2021

The present investigation describes a formulation of a live attenuated Salmonella Gallinarium (SG... more The present investigation describes a formulation of a live attenuated Salmonella Gallinarium (SG) vaccine candidate against H9N2 influenza and SG infections in chickens. The formulation consists of an equal ratio of three strains, JOL2158, JOL2113, and JOL2074, which deliver hemagglutinin; HA1, HA2, and matrix protein 2 (M2e):: CD154 fusion (M2eCD154) antigens designed for broad protection against the field-matched H9N2 serotypes. The vaccine was completely safe at the average inoculation doses of 108 and 109 CFU/bird/0.2 mL in phosphate-buffered saline (PBS) used in the study. Bird immunization as a single oral inoculation could significantly engage humoral IgG, mucosal IgA, and cell-mediated immune responses against each immunized antigen, compared to the PBS control group (P < 0.05). The immunological correlates were comparable with the level of protection derived against the H9N2 and SG challenge, which resulted in significant protection against the H9N2 but only partial protection against the SG challenge as we compared against the PBS control group. The level of protection against H9N2 was investigated by determining the viral copy number and histopathological assessment of lung tissues. The results indicated a significant reduction in viral activity and recovery of lung inflammation towards the 14th-day post-challenge in a dose-dependent manner. Upon SG challenge, birds in the PBS control group experienced 100 % mortality, while 40 % and 70 % protection was observed in the SG-immunized groups for each respective dose of inoculation. The present SG-mediated immunization strategy proposes a rapid and reliable vaccine development process that can be effectively used against influenza strains such as H9N2 and holds the potential to minimize fowl typhoid caused by SG strains, mitigating two economically important diseases in the poultry industry.

Phylogenetic relationships and antibiotic resistance of Vibrio parahaemolyticus isolates related to acute hepatopancreatic necrosis disease in Korea

Aquaculture, 2021

Abstract In this study, we performed genotype analysis based on multi-locus sequence typing (MLST... more Abstract In this study, we performed genotype analysis based on multi-locus sequence typing (MLST) and antibiotic resistance of 27 pirAB-harboring Vibrio parahaemolyticus (Vp AHPND) isolates recovered from white leg shrimp (Penaeus vannamei) from acute hepatopancreatic necrosis disease (AHPND) affected farms (in 2016, n = 22) and retail markets (in 2016, n = 5) of Korea. Most Vp AHPND isolates were resistant to colistin, ampicillin, and streptomycin but susceptible to other antibiotics. The comparison of their antibiotic resistance to that of non-Vp AHPND isolates revealed a significantly higher resistance of Vp AHPND isolates to streptomycin. No differences, however, were observed in the minimal inhibitory concentration median (MIC50), 90th percentile (MIC90), and average multiple antibiotic resistance (MAR) index between the two groups. In MLST analysis, sequence types could not be defined for 19 isolates owing to the failure of recA gene sequencing. Seven new STs were found in five and two isolates from retail markets and AHPND affected farms, respectively. Based on the MLST-based phylogenetic tree, all isolates were divided into eight clades; 22 isolates from AHPND affected farms were grouped into three clades, and five isolates from retail markets formed singleton clades. These data suggest that most AHPND outbreaks in Korea may be related to Vp AHPND isolates originating from a common clone through the acquisition of pirAB. Further, the detection of Vp AHPND from retail shrimp samples suggests that the pathogen may be widely distributed in shrimp aquaculture and/or the environment of Korea.

Veterinary Microbiology, 2020

Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characte... more Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characterization in dairy cattle

Background Multifocal spherical nonstaining cavities and gram-positive, rod-shaped, and endospore... more Background Multifocal spherical nonstaining cavities and gram-positive, rod-shaped, and endospore-forming bacteria were found in the liver of a sow that died suddenly. Clostridium novyi type B was identified and isolated from the sudden death case and the isolate was characterized by molecular analyses and bioassays in the current study. Results C. novyi was isolated from the liver and was confirmed as C. novyi type B by differential PCR. The C. novyi isolate fermented glucose and maltose and demonstrated lecithinase activity, and the cell-free culture supernatant of the C. novyi isolate exhibited cytotoxicity toward Vero cells, demonstrating that the isolate produces toxins. In addition, whole-genome sequencing of the C. novyi isolate was performed, and the complete sequences of the chromosome (2.29 Mbp) and two plasmids (134 and 68 kbp) were identified for the first time. Based on genome annotation, 7 genes were identified as glycosyltransferases, which are known as alpha toxins; ...

Korean Journal of Veterinary Service, 2016

Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin... more Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) which expresses F18 fimbriae and/or Stx type 2e (Stx2e). While STEC causes a severe illness including hemorrhagic colitis and hemolytic-uremic syndrome in humans, it induces damage to the vascular endothelium, which results in edema, hemorrhage, and microthrombosis, leading in high mortality in pigs. In the present study, we cultured Stx2e-producing E. coli field isolates from conventional pig farms that experienced sudden deaths previously with symptoms similar to porcine edema disease, which were further investigated with Shiga toxin profiles. A total of 43 strains were identified from the collected samples by F18 or Stx2e specific PCR. Based on the PCR, 42 isolates out of 43 isolates were proved to carry one of F18 or Stx2e genes and 14 isolates to carry both F18 and Stx2e genes. All of the 30 isolates that harbored Stx2e gene induced the cytopathic effect (CPE) in vero cells and especially, the isolate 150229 produced the highest level of Shiga toxin. Therefore, we identified the virulence genes (F18 and Stx2e) and demonstrated Shiga toxin-producing abilities from porcine edema disease causing E. coli filed isolates. These results suggested that one of the isolates could be a vaccine antigen candidate against STEC through further investigating to elicit an immune response.

Korean Journal of Veterinary Service, 2016

Clostridium novyi (C. novyi) is a gram positive, non-capsulated, motile, obligatory anaerobe that... more Clostridium novyi (C. novyi) is a gram positive, non-capsulated, motile, obligatory anaerobe that produces endospores. Both C. novyi type A and B produce a bacteriophage encoded lethal alpha toxin which belongs to a family of large clostridial cytotoxins. These large clostridial cytotoxins of C. novyi bind to the uncharacterized receptors on host vascular endothelial cells, which leads to the loss of integrity of the vascular endothelium with subsequent edema, refractory hypotension, organ failure, and sudden death. A total of 13 sudden death cases were submitted to Chonbuk National University-Veterinary Diagnostic Center between June and October, 2015. The samples, mainly liver, were collected in sterile vials after necropsy and processed within 12∼24 hours for diagnosis, isolation and identification of C. novyi. All of the 4 gram positive samples showed amplification by PCR. Out of 4 positive samples, 3 were detected to be C. novyi type B and 1 was detected as C. novyi type A. Based on the 16S rDNA sequence analysis, 1 case (150564) showed 99% similarity with C. novyi type A while other 3 cases (150388, 150557 and 150775) presented 99% similarity with C. novyi type B. Based on the results, C. novyi was found to be prevalent in Korean pig farms and causes sudden death to finishing pigs or sows during summer season. Thus, C. novyi should be considered for differential diagnosis on sudden death cases during the summer season.

Molecules, 2019

DiNap [(E)-1-(2-hydroxy-4,6-dimethoxyphenyl)-3-(naphthalen-1-yl)prop-2-en-1-one], an analog of a ... more DiNap [(E)-1-(2-hydroxy-4,6-dimethoxyphenyl)-3-(naphthalen-1-yl)prop-2-en-1-one], an analog of a natural product (the chalcone flavokawain), was synthesized and characterized in this study. Porcine reproductive and respiratory syndrome virus (PRRSV) is the most challenging threat to the swine industry worldwide. Currently, commercially available vaccines are ineffective for controlling porcine reproductive and respiratory syndrome (PRRS) in pigs. Therefore, a pharmacological intervention may represent an alternative control measure for PRRSV infection. Hence, the present study evaluated the effects of DiNap on the replication of VR2332 (a prototype strain of type 2 PRRSV). Initially, in vitro antiviral assays against VR2332 were performed in MARC-145 cells and porcine alveolar macrophages (PAMs). Following this, a pilot study was conducted in a pig model to demonstrate the effects of DiNap following VR2332 infection. DiNap inhibited VR2332 replication in both cell lines in a dose-de...

Journal of Veterinary Medical Science, 2018

The broad-spectrum lytic capability of Salmonella bacteriophages against various Salmonella speci... more The broad-spectrum lytic capability of Salmonella bacteriophages against various Salmonella species was evaluated to determine their potential as an alternative for antibiotics, and the safety and preventive effects of the bacteriophages were assessed on mice and pigs. Four bacteriophage cocktails were prepared using 13 bacteriophages, and the lytic capability of the four bacteriophage cocktails was tested using Salmonella reference strains and field isolates. Bacteriophage cocktail C (SEP-1, SGP-1, STP-1, SS3eP-1, STP-2, SChP-1, SAP-1, SAP-2; ≥10 9 pfu/ ml) showed the best lytic activity against the Salmonella reference strains (100% of 34) and field isolates (92.5% of 107). Fifty mice were then orally inoculated with bacteriophage cocktail C to determine the distribution of bacteriophages in various organs, blood and feces. The effects of bacteriophages on Salmonella infection in weaned pigs (n=15) were also evaluated through an experimental challenge with Salmonella Typhimurium after treatment with bacteriophage cocktail C. All mice exhibited distribution of the bacteriophages in all organs, blood and feces until 15 days post infection (dpi). After 35 dpi, bacteriophages were not detected in any of these specimens. As demonstrated in a pig challenge study, treatment with bacteriophage cocktail C reduced the level of Salmonella shedding in feces. The metagenomic analyses of these pig feces also revealed that bacteriophage treatment decreased the number of species of the Enterobacteriaceae family without significant disturbance to the normal fecal flora. This study showed that bacteriophages effectively controlled Salmonella in a pig challenge model and could be a good alternative for antibiotics to control Salmonella infection.

Acta Veterinaria, 2017

produces a higher molecular mass poly-γ-glutamic acid (γ-PGA). Recently, previous studies have de... more produces a higher molecular mass poly-γ-glutamic acid (γ-PGA). Recently, previous studies have demonstrated immune stimulation and an antitumor effect of the high molecular mass γ-PGA using various mouse models although these effects have not been shown in other species of animals. Therefore, the current study was conducted to determine the effect of γ-PGA in pigs with and without PRRSV infection. PRRS-negative pigs were intramuscularly injected with 1, 3, or 5 ml of 20 mg/m

Journal of virology, Jan 17, 2016

In a previous study, ribavirin-resistant PRRSV mutants (RVRp13 and RVRp22) were selected, and the... more In a previous study, ribavirin-resistant PRRSV mutants (RVRp13 and RVRp22) were selected, and their resistance against random mutation was shown in cultured cells. In the current study, these ribavirin-resistant mutants were evaluated in terms of their genetic and phenotypic stability during 3 pig-to-pig passages in comparison with MLV (Ingelvac® PRRS MLV). Pigs challenged with RVRp22 had significantly lower (p<0.05) viral loads in sera and tissues than pigs challenged with MLV or RVRp13 at the first passage, and the attenuated replication of RVRp22 was maintained until the third passage. Viral loads in sera and tissues dramatically increased in pigs challenged with MLV or RVRp13 during the second passage. Consistently, all five sequences associated with the attenuation of virulent PRRSV in RVRp13 and MLV quickly reverted to wild-type sequences during the passages, but two attenuation sequences were maintained in RVRp22 even after the third passage. In addition, RVRp22 showed a s...

Effect of polymorphisms in the GBP1, Mx1 and CD163 genes on host responses to PRRSV infection in pigs

Veterinary Microbiology, 2016

Porcine reproductive and respiratory syndrome (PRRS) is the most economically important disease t... more Porcine reproductive and respiratory syndrome (PRRS) is the most economically important disease to the swine industry, and effective prevention strategy for this disease is still required. Guanylate-binding protein 1 (GBP1) and myxovirus resistance protein 1 (Mx1) are two important proteins belonging to the GTPase superfamily that have been previously described to show antiviral effects. CD163 is considered the most important receptor for PRRSV attachment and internalization. Therefore, the aim of the present study was to evaluate the effects of these genes on host resistance against PRRSV infection in conjunction with the host immune response following PRRSV challenge. The results showed that pigs with AG genotype for the GBP1 exon2 exhibited a significantly higher average daily weight gain (ADWG) and lower average viremia than AA or GG genotype. Furthermore, pigs harbouring the AG genotype for the GBP1 gene presented greater CD4(+)CD25(+) and CD8(+)CD25(+) T cell populations at 4 and 18 days post challenge (dpc), respectively, as compared with other genotypes whereas pigs with CC genotype for the CD163 gene displayed significantly higher nucleocapsid-specific antibody titers at 11dpc. However, pigs with a single 11-bp deletion or insertion in the Mx1 gene did not show significant differences in either weight gain or viremia. Based on these results, we concluded that GBP1 is most significantly associated with resistance against PRRSV infection and efficient T cell activation in pigs.

Indian Journal of Pharmaceutical Education and Research, 2015

This study was aimed to partially purify the exopolysaccharide (EPS) from the culture of Lactobac... more This study was aimed to partially purify the exopolysaccharide (EPS) from the culture of Lactobacillus plantarum YML009 using ethanol precipitation method with a yield of 260 mg/L. Analytical evaluationby Bradford and Phenolsulphuric methods revealed the presence of 2.2% and 68.1% total protein and total sugar contents in partially purified EPS, respectively. Further, to confirm the biological potential, the EPS was evaluated for its antioxidant activity in various scavenging models including DPPH and nitrite radicals as well as reducing power ability. The partially purified EPS (5-40 mg/mL) displayed considerable amount of antioxidant efficacy on scavenging DPPH and nitrite radicals by 44.73%, and 43.93%, respectively. Moreover, EPS showed potentreducing power capacity along with total phenolic content 18.96 µg/mg of GAE.

Journal of Veterinary Medical Science, 2016

Two commercial PRRSV ELISA kits (IDEXX and Bionote) were evaluated for their sensitivity and spec... more Two commercial PRRSV ELISA kits (IDEXX and Bionote) were evaluated for their sensitivity and specificity using 476 PRRSpositive serum samples collected from 7 animal challenge experiments and 1,000 PRRS-negative sera. Both ELISA kits exhibited 100% sensitivity with sera collected 14 to 42 days post-infection, and the results from the kits were highly correlated (R 2 =0.9207). The specificity of IDEXX or Bionote kit was 99.9% or 99.7%, respectively. In addition, the Bionote ELISA kit was used to examine 100 sera that were determined to be falsely positive either by IDEXX 2XR or 3XR ELISA, and only 7 of these samples were found to be positive. These results indicate that both ELISA kits exhibited similar levels of sensitivity and specificity and would complement one another for the verification of false-positive samples.

Korean Journal of Veterinary Service, 2014

Porcine reproductive and respiratory syndrome virus (PRRSV) causes major economic losses to the K... more Porcine reproductive and respiratory syndrome virus (PRRSV) causes major economic losses to the Korean pig industry. ELISA tests using recombinant nucleocapsid protein of PRRSV have been most commonly used for PRRS diagnostics. In the current study, two commercial PRRSV ELISA kits (Bionote PRRSV Antibody ELISA and IDEXX 3XR PRRS Antibody ELISA) have been compared using sera collected from 19 swine farms in various stages of PRRSV infection confirmed by professional diagnostic centers. Thus 130 sera collected from 5 different farms with active PRRSV infection, 130 sera from 6 different farms with PRRS-stabilized status, and 140 sera from 8 different farms with PRRS-free status were evaluated to determine the correlation of test results between those ELISA kits. Both ELISA kits showed a good correlation [PRRSV-positive farms (R 2 =0.6375) and stabilized farms (R 2 =0.8928)] in sample-to-positive (S/P) ratio va lues. Among the 140 sera from negative farms, one sample was falsely positive by either of the ELISA kits. In conclusion, both of the ELISA kits showed a good correlation when applied on field samples collected from farms at various stages of PRRSV infection. Bionote ELISA or IDEXX ELISA gave a false positive result on 1 out of 140 negative samples so their specificity was calculated as 99.3%. Therefore, Bionote ELISA would be a good complementary and alternative method for IDEXX ELISA kit, and vice versa.

Journal of Life Science, 2013

During the collection of boar semen, bacterial contamination usually occurs. The contamination ha... more During the collection of boar semen, bacterial contamination usually occurs. The contamination has deleterious effects both on semen quality and on sow fertility. The majority of contaminants are gram-negative bacteria, especially Serratia marcescens. In this study, we developed a PCR assay for the identification of S. marcescens targeting the luxS gene (GenBank no. EF164926). S. marcescens yielded a specific 306 bp PCR product. However, no amplification was observed in the other strains tested. The detection limit of PCR was 50 pg/µl of template DNA of S. marcescens. The antimicrobial susceptibility patterns of S. marcescens isolated from boar semen were tested using the disk diffusion method. Gentamicin, ceftiofur, florfenicol, and neomycin showed high sensitivity in this test. The minimum inhibitory concentration (MIC) was also determined by the broth microdilution method. The MIC90 values of ceftiofur, enrofloxacin, gentamicin, and neomycin were 8, 8, 8, and 16 µg/ml, respectively. These results indicate that PCR amplification of the luxS gene is a reliable and effective method for the identification of S. marcescens and that ceftiofur, enrofloxacin, gentamicin, and neomycin are effective semen extenders for controlling S. marcescens.

This study explored the optimal culture conditions for maximizing shiga toxin production in Stx2e... more This study explored the optimal culture conditions for maximizing shiga toxin production in Stx2e-producing Escherichia coli (STEC) 150229, isolated from porcine edema disease (ED), with the goal of preparing a Stx2e toxoid vaccine candidate. High cytotoxicity was observed for this strain [tissue culture cytotoxic dose 50% (10 4 TCCD 50 /100 μl)] from 48 h after incubation. Stx2e was overexpressed by transforming pStx2e A into STEC 150229, resulting in the production of recombinant Stx2e A/B complex combined with intrinsic Stx2e B. The enhanced production of Stx2e was evaluated based on the level of cytotoxicity against Vero cells. The highest cytotoxicity (10 5 TCCD 50 /100 μl) was observed with the samples of recombinant Stx2e A/B complex eluted with 500 mM imidazole at 48 h of incubation. In conclusion, the recombinant Stx2e A protein forms an active protein complex with the intrinsic Stx2e B component from STEC 150229, producing high levels of shiga toxin.

Additional file 1 of Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

Additional file 1. The identified genes of the C. novyi isolate.

Comparison of the pathogenicity of porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in pregnant sows

Archives of Virology, 2022

To date, few studies related to the evaluation of the pathogenicity of different PRRSV isolates u... more To date, few studies related to the evaluation of the pathogenicity of different PRRSV isolates using a reproductive model have been undertaken, and the main focus has remained on respiratory models using young pigs. This study aimed to evaluate the pathogenicity of two PRRSV-1 isolates (D40 and CBNU0495) and two PRRSV-2 isolates (K07-2273 and K08-1054) in a reproductive model. Pregnant sows were experimentally infected with PRRSV at gestational day 93 or used as an uninfected negative control. Sera were collected at 0, 3, 7, 14, and 19 days post-challenge (dpc) for virological and serological assays. At 19 dpc, all sows were euthanized, and their fetuses were recovered by performing cesarean section and immediately euthanized for sample collection. Here, compared to the other isolates, the CBNU0495 isolate replicated most efficiently in the pregnant sows, and K07-2273 produced the highest rate of reproductive failure even though it did not replicate as efficiently as the other isolates in sows and fetuses, indicating that vertical transmission and reproductive failure due to PRRSV infection do not have any significant correlation with the viral loads in samples from sows and fetuses. Similarly, the viral loads and the histopathological lesions did not show any correlation with each other, as the PRRSV-2-infected groups displayed more prominent and frequent histopathological lesions with lower viral loads than the PRRSV-1-infected groups. However, viral loads in the myometrium/endometrium might be related to the spreading of PRRSV in the fetuses, which affected the birth weight of live fetuses. This study contributes to a better understanding of the pathogenicity of the most prevalent Korean PRRSVs in a reproductive model.

Differences in Manufacturing Process and Quality between Cheonggukjang for Use in the Raw and Cheonggukjang for Stew

Food Science and Biotechnology, 2008

When cheonggukjang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-ter... more When cheonggukjang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-term fermentation for 14-18 hr appeared to be the optimal for the raw cheonggukjang to avoid the formation of a bitter taste and to contain a high concentration of free sugars, whereas a long-term fermentation for more than 4 days was the optimal for the cheonggukjang for stew in order to contain a high concentration of free amino and organic acids, which are responsible for sweet, savory, and bitter tastes present in stewed cheonggukjang. During activation of murine splenic T cells with phytohemagglutinin (PHA), the presence of either poly-γ-glutamic acid (γ-PGA) or partially hydrolyzed γ-PGA resulted in reduction in the level of interferon-γ production and enhancement in the level of interleukin-5 production, possibly due to suppression of Th1 activity and augmentation of Th2 activity. Taken together these results indicate that the raw cheonggukjang and the cheonggukjang for stew are diff...

Gut microbiome responses of pigs to a high dose of deoxynivalenol (DON) in feed

Single oral immunization of an attenuated Salmonella Gallinarium formulation consisting of equal quantities of strains secreting H9N2 hemagglutinin-HA1, HA2, and M2eCD154 induces significant protection against H9N2 and partial protection against Salmonella Gallinarium challenge in chickens

Veterinary Immunology and Immunopathology, 2021

The present investigation describes a formulation of a live attenuated Salmonella Gallinarium (SG... more The present investigation describes a formulation of a live attenuated Salmonella Gallinarium (SG) vaccine candidate against H9N2 influenza and SG infections in chickens. The formulation consists of an equal ratio of three strains, JOL2158, JOL2113, and JOL2074, which deliver hemagglutinin; HA1, HA2, and matrix protein 2 (M2e):: CD154 fusion (M2eCD154) antigens designed for broad protection against the field-matched H9N2 serotypes. The vaccine was completely safe at the average inoculation doses of 108 and 109 CFU/bird/0.2 mL in phosphate-buffered saline (PBS) used in the study. Bird immunization as a single oral inoculation could significantly engage humoral IgG, mucosal IgA, and cell-mediated immune responses against each immunized antigen, compared to the PBS control group (P < 0.05). The immunological correlates were comparable with the level of protection derived against the H9N2 and SG challenge, which resulted in significant protection against the H9N2 but only partial protection against the SG challenge as we compared against the PBS control group. The level of protection against H9N2 was investigated by determining the viral copy number and histopathological assessment of lung tissues. The results indicated a significant reduction in viral activity and recovery of lung inflammation towards the 14th-day post-challenge in a dose-dependent manner. Upon SG challenge, birds in the PBS control group experienced 100 % mortality, while 40 % and 70 % protection was observed in the SG-immunized groups for each respective dose of inoculation. The present SG-mediated immunization strategy proposes a rapid and reliable vaccine development process that can be effectively used against influenza strains such as H9N2 and holds the potential to minimize fowl typhoid caused by SG strains, mitigating two economically important diseases in the poultry industry.

Phylogenetic relationships and antibiotic resistance of Vibrio parahaemolyticus isolates related to acute hepatopancreatic necrosis disease in Korea

Aquaculture, 2021

Abstract In this study, we performed genotype analysis based on multi-locus sequence typing (MLST... more Abstract In this study, we performed genotype analysis based on multi-locus sequence typing (MLST) and antibiotic resistance of 27 pirAB-harboring Vibrio parahaemolyticus (Vp AHPND) isolates recovered from white leg shrimp (Penaeus vannamei) from acute hepatopancreatic necrosis disease (AHPND) affected farms (in 2016, n = 22) and retail markets (in 2016, n = 5) of Korea. Most Vp AHPND isolates were resistant to colistin, ampicillin, and streptomycin but susceptible to other antibiotics. The comparison of their antibiotic resistance to that of non-Vp AHPND isolates revealed a significantly higher resistance of Vp AHPND isolates to streptomycin. No differences, however, were observed in the minimal inhibitory concentration median (MIC50), 90th percentile (MIC90), and average multiple antibiotic resistance (MAR) index between the two groups. In MLST analysis, sequence types could not be defined for 19 isolates owing to the failure of recA gene sequencing. Seven new STs were found in five and two isolates from retail markets and AHPND affected farms, respectively. Based on the MLST-based phylogenetic tree, all isolates were divided into eight clades; 22 isolates from AHPND affected farms were grouped into three clades, and five isolates from retail markets formed singleton clades. These data suggest that most AHPND outbreaks in Korea may be related to Vp AHPND isolates originating from a common clone through the acquisition of pirAB. Further, the detection of Vp AHPND from retail shrimp samples suggests that the pathogen may be widely distributed in shrimp aquaculture and/or the environment of Korea.

Veterinary Microbiology, 2020

Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characte... more Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characterization in dairy cattle

Background Multifocal spherical nonstaining cavities and gram-positive, rod-shaped, and endospore... more Background Multifocal spherical nonstaining cavities and gram-positive, rod-shaped, and endospore-forming bacteria were found in the liver of a sow that died suddenly. Clostridium novyi type B was identified and isolated from the sudden death case and the isolate was characterized by molecular analyses and bioassays in the current study. Results C. novyi was isolated from the liver and was confirmed as C. novyi type B by differential PCR. The C. novyi isolate fermented glucose and maltose and demonstrated lecithinase activity, and the cell-free culture supernatant of the C. novyi isolate exhibited cytotoxicity toward Vero cells, demonstrating that the isolate produces toxins. In addition, whole-genome sequencing of the C. novyi isolate was performed, and the complete sequences of the chromosome (2.29 Mbp) and two plasmids (134 and 68 kbp) were identified for the first time. Based on genome annotation, 7 genes were identified as glycosyltransferases, which are known as alpha toxins; ...

Korean Journal of Veterinary Service, 2016

Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin... more Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) which expresses F18 fimbriae and/or Stx type 2e (Stx2e). While STEC causes a severe illness including hemorrhagic colitis and hemolytic-uremic syndrome in humans, it induces damage to the vascular endothelium, which results in edema, hemorrhage, and microthrombosis, leading in high mortality in pigs. In the present study, we cultured Stx2e-producing E. coli field isolates from conventional pig farms that experienced sudden deaths previously with symptoms similar to porcine edema disease, which were further investigated with Shiga toxin profiles. A total of 43 strains were identified from the collected samples by F18 or Stx2e specific PCR. Based on the PCR, 42 isolates out of 43 isolates were proved to carry one of F18 or Stx2e genes and 14 isolates to carry both F18 and Stx2e genes. All of the 30 isolates that harbored Stx2e gene induced the cytopathic effect (CPE) in vero cells and especially, the isolate 150229 produced the highest level of Shiga toxin. Therefore, we identified the virulence genes (F18 and Stx2e) and demonstrated Shiga toxin-producing abilities from porcine edema disease causing E. coli filed isolates. These results suggested that one of the isolates could be a vaccine antigen candidate against STEC through further investigating to elicit an immune response.

Korean Journal of Veterinary Service, 2016

Clostridium novyi (C. novyi) is a gram positive, non-capsulated, motile, obligatory anaerobe that... more Clostridium novyi (C. novyi) is a gram positive, non-capsulated, motile, obligatory anaerobe that produces endospores. Both C. novyi type A and B produce a bacteriophage encoded lethal alpha toxin which belongs to a family of large clostridial cytotoxins. These large clostridial cytotoxins of C. novyi bind to the uncharacterized receptors on host vascular endothelial cells, which leads to the loss of integrity of the vascular endothelium with subsequent edema, refractory hypotension, organ failure, and sudden death. A total of 13 sudden death cases were submitted to Chonbuk National University-Veterinary Diagnostic Center between June and October, 2015. The samples, mainly liver, were collected in sterile vials after necropsy and processed within 12∼24 hours for diagnosis, isolation and identification of C. novyi. All of the 4 gram positive samples showed amplification by PCR. Out of 4 positive samples, 3 were detected to be C. novyi type B and 1 was detected as C. novyi type A. Based on the 16S rDNA sequence analysis, 1 case (150564) showed 99% similarity with C. novyi type A while other 3 cases (150388, 150557 and 150775) presented 99% similarity with C. novyi type B. Based on the results, C. novyi was found to be prevalent in Korean pig farms and causes sudden death to finishing pigs or sows during summer season. Thus, C. novyi should be considered for differential diagnosis on sudden death cases during the summer season.

Molecules, 2019

DiNap [(E)-1-(2-hydroxy-4,6-dimethoxyphenyl)-3-(naphthalen-1-yl)prop-2-en-1-one], an analog of a ... more DiNap [(E)-1-(2-hydroxy-4,6-dimethoxyphenyl)-3-(naphthalen-1-yl)prop-2-en-1-one], an analog of a natural product (the chalcone flavokawain), was synthesized and characterized in this study. Porcine reproductive and respiratory syndrome virus (PRRSV) is the most challenging threat to the swine industry worldwide. Currently, commercially available vaccines are ineffective for controlling porcine reproductive and respiratory syndrome (PRRS) in pigs. Therefore, a pharmacological intervention may represent an alternative control measure for PRRSV infection. Hence, the present study evaluated the effects of DiNap on the replication of VR2332 (a prototype strain of type 2 PRRSV). Initially, in vitro antiviral assays against VR2332 were performed in MARC-145 cells and porcine alveolar macrophages (PAMs). Following this, a pilot study was conducted in a pig model to demonstrate the effects of DiNap following VR2332 infection. DiNap inhibited VR2332 replication in both cell lines in a dose-de...

Journal of Veterinary Medical Science, 2018

The broad-spectrum lytic capability of Salmonella bacteriophages against various Salmonella speci... more The broad-spectrum lytic capability of Salmonella bacteriophages against various Salmonella species was evaluated to determine their potential as an alternative for antibiotics, and the safety and preventive effects of the bacteriophages were assessed on mice and pigs. Four bacteriophage cocktails were prepared using 13 bacteriophages, and the lytic capability of the four bacteriophage cocktails was tested using Salmonella reference strains and field isolates. Bacteriophage cocktail C (SEP-1, SGP-1, STP-1, SS3eP-1, STP-2, SChP-1, SAP-1, SAP-2; ≥10 9 pfu/ ml) showed the best lytic activity against the Salmonella reference strains (100% of 34) and field isolates (92.5% of 107). Fifty mice were then orally inoculated with bacteriophage cocktail C to determine the distribution of bacteriophages in various organs, blood and feces. The effects of bacteriophages on Salmonella infection in weaned pigs (n=15) were also evaluated through an experimental challenge with Salmonella Typhimurium after treatment with bacteriophage cocktail C. All mice exhibited distribution of the bacteriophages in all organs, blood and feces until 15 days post infection (dpi). After 35 dpi, bacteriophages were not detected in any of these specimens. As demonstrated in a pig challenge study, treatment with bacteriophage cocktail C reduced the level of Salmonella shedding in feces. The metagenomic analyses of these pig feces also revealed that bacteriophage treatment decreased the number of species of the Enterobacteriaceae family without significant disturbance to the normal fecal flora. This study showed that bacteriophages effectively controlled Salmonella in a pig challenge model and could be a good alternative for antibiotics to control Salmonella infection.

Acta Veterinaria, 2017

produces a higher molecular mass poly-γ-glutamic acid (γ-PGA). Recently, previous studies have de... more produces a higher molecular mass poly-γ-glutamic acid (γ-PGA). Recently, previous studies have demonstrated immune stimulation and an antitumor effect of the high molecular mass γ-PGA using various mouse models although these effects have not been shown in other species of animals. Therefore, the current study was conducted to determine the effect of γ-PGA in pigs with and without PRRSV infection. PRRS-negative pigs were intramuscularly injected with 1, 3, or 5 ml of 20 mg/m

Journal of virology, Jan 17, 2016

In a previous study, ribavirin-resistant PRRSV mutants (RVRp13 and RVRp22) were selected, and the... more In a previous study, ribavirin-resistant PRRSV mutants (RVRp13 and RVRp22) were selected, and their resistance against random mutation was shown in cultured cells. In the current study, these ribavirin-resistant mutants were evaluated in terms of their genetic and phenotypic stability during 3 pig-to-pig passages in comparison with MLV (Ingelvac® PRRS MLV). Pigs challenged with RVRp22 had significantly lower (p<0.05) viral loads in sera and tissues than pigs challenged with MLV or RVRp13 at the first passage, and the attenuated replication of RVRp22 was maintained until the third passage. Viral loads in sera and tissues dramatically increased in pigs challenged with MLV or RVRp13 during the second passage. Consistently, all five sequences associated with the attenuation of virulent PRRSV in RVRp13 and MLV quickly reverted to wild-type sequences during the passages, but two attenuation sequences were maintained in RVRp22 even after the third passage. In addition, RVRp22 showed a s...

Effect of polymorphisms in the GBP1, Mx1 and CD163 genes on host responses to PRRSV infection in pigs

Veterinary Microbiology, 2016

Porcine reproductive and respiratory syndrome (PRRS) is the most economically important disease t... more Porcine reproductive and respiratory syndrome (PRRS) is the most economically important disease to the swine industry, and effective prevention strategy for this disease is still required. Guanylate-binding protein 1 (GBP1) and myxovirus resistance protein 1 (Mx1) are two important proteins belonging to the GTPase superfamily that have been previously described to show antiviral effects. CD163 is considered the most important receptor for PRRSV attachment and internalization. Therefore, the aim of the present study was to evaluate the effects of these genes on host resistance against PRRSV infection in conjunction with the host immune response following PRRSV challenge. The results showed that pigs with AG genotype for the GBP1 exon2 exhibited a significantly higher average daily weight gain (ADWG) and lower average viremia than AA or GG genotype. Furthermore, pigs harbouring the AG genotype for the GBP1 gene presented greater CD4(+)CD25(+) and CD8(+)CD25(+) T cell populations at 4 and 18 days post challenge (dpc), respectively, as compared with other genotypes whereas pigs with CC genotype for the CD163 gene displayed significantly higher nucleocapsid-specific antibody titers at 11dpc. However, pigs with a single 11-bp deletion or insertion in the Mx1 gene did not show significant differences in either weight gain or viremia. Based on these results, we concluded that GBP1 is most significantly associated with resistance against PRRSV infection and efficient T cell activation in pigs.

Indian Journal of Pharmaceutical Education and Research, 2015

This study was aimed to partially purify the exopolysaccharide (EPS) from the culture of Lactobac... more This study was aimed to partially purify the exopolysaccharide (EPS) from the culture of Lactobacillus plantarum YML009 using ethanol precipitation method with a yield of 260 mg/L. Analytical evaluationby Bradford and Phenolsulphuric methods revealed the presence of 2.2% and 68.1% total protein and total sugar contents in partially purified EPS, respectively. Further, to confirm the biological potential, the EPS was evaluated for its antioxidant activity in various scavenging models including DPPH and nitrite radicals as well as reducing power ability. The partially purified EPS (5-40 mg/mL) displayed considerable amount of antioxidant efficacy on scavenging DPPH and nitrite radicals by 44.73%, and 43.93%, respectively. Moreover, EPS showed potentreducing power capacity along with total phenolic content 18.96 µg/mg of GAE.

Journal of Veterinary Medical Science, 2016

Two commercial PRRSV ELISA kits (IDEXX and Bionote) were evaluated for their sensitivity and spec... more Two commercial PRRSV ELISA kits (IDEXX and Bionote) were evaluated for their sensitivity and specificity using 476 PRRSpositive serum samples collected from 7 animal challenge experiments and 1,000 PRRS-negative sera. Both ELISA kits exhibited 100% sensitivity with sera collected 14 to 42 days post-infection, and the results from the kits were highly correlated (R 2 =0.9207). The specificity of IDEXX or Bionote kit was 99.9% or 99.7%, respectively. In addition, the Bionote ELISA kit was used to examine 100 sera that were determined to be falsely positive either by IDEXX 2XR or 3XR ELISA, and only 7 of these samples were found to be positive. These results indicate that both ELISA kits exhibited similar levels of sensitivity and specificity and would complement one another for the verification of false-positive samples.

Korean Journal of Veterinary Service, 2014

Porcine reproductive and respiratory syndrome virus (PRRSV) causes major economic losses to the K... more Porcine reproductive and respiratory syndrome virus (PRRSV) causes major economic losses to the Korean pig industry. ELISA tests using recombinant nucleocapsid protein of PRRSV have been most commonly used for PRRS diagnostics. In the current study, two commercial PRRSV ELISA kits (Bionote PRRSV Antibody ELISA and IDEXX 3XR PRRS Antibody ELISA) have been compared using sera collected from 19 swine farms in various stages of PRRSV infection confirmed by professional diagnostic centers. Thus 130 sera collected from 5 different farms with active PRRSV infection, 130 sera from 6 different farms with PRRS-stabilized status, and 140 sera from 8 different farms with PRRS-free status were evaluated to determine the correlation of test results between those ELISA kits. Both ELISA kits showed a good correlation [PRRSV-positive farms (R 2 =0.6375) and stabilized farms (R 2 =0.8928)] in sample-to-positive (S/P) ratio va lues. Among the 140 sera from negative farms, one sample was falsely positive by either of the ELISA kits. In conclusion, both of the ELISA kits showed a good correlation when applied on field samples collected from farms at various stages of PRRSV infection. Bionote ELISA or IDEXX ELISA gave a false positive result on 1 out of 140 negative samples so their specificity was calculated as 99.3%. Therefore, Bionote ELISA would be a good complementary and alternative method for IDEXX ELISA kit, and vice versa.

Journal of Life Science, 2013

During the collection of boar semen, bacterial contamination usually occurs. The contamination ha... more During the collection of boar semen, bacterial contamination usually occurs. The contamination has deleterious effects both on semen quality and on sow fertility. The majority of contaminants are gram-negative bacteria, especially Serratia marcescens. In this study, we developed a PCR assay for the identification of S. marcescens targeting the luxS gene (GenBank no. EF164926). S. marcescens yielded a specific 306 bp PCR product. However, no amplification was observed in the other strains tested. The detection limit of PCR was 50 pg/µl of template DNA of S. marcescens. The antimicrobial susceptibility patterns of S. marcescens isolated from boar semen were tested using the disk diffusion method. Gentamicin, ceftiofur, florfenicol, and neomycin showed high sensitivity in this test. The minimum inhibitory concentration (MIC) was also determined by the broth microdilution method. The MIC90 values of ceftiofur, enrofloxacin, gentamicin, and neomycin were 8, 8, 8, and 16 µg/ml, respectively. These results indicate that PCR amplification of the luxS gene is a reliable and effective method for the identification of S. marcescens and that ceftiofur, enrofloxacin, gentamicin, and neomycin are effective semen extenders for controlling S. marcescens.