Establishment of the Foot-and-Mouth Disease Virus Type Asia1 Expressing the HiBiT Protein: A Useful Tool for a NanoBiT Split Luciferase Assay.

Foot-and-mouth disease virus (FMDV) is a highly contagious virus that affects cloven-hoofed animals and causes severe economic losses in the livestock industry. Given that this high-risk pathogen has to be handled in a biosafety level (BSL)-3 facility for safety reasons and the limited availability of BSL-3 laboratories, experiments on FMDV call for more attention. Therefore, we aimed to develop an FMDV experimental model that can be handled in BSL-2 laboratories.

High prevalence of a gene cluster conferring resistance to streptomycin, sulfonamide, and tetracycline in Escherichia coli isolated from indigenous wild birds.

A total of 116 Escherichia coli isolates from cecal contents of 81 indigenous wild birds in Korea were tested for antimicrobial susceptibility. Seventy-one isolates from sparrows (Passer montanus) and one isolate from doves (Columba livia) were resistant to three antimicrobials, including streptomycin, sulfonamide, and tetracycline (SSuT). PCR and subsequent sequence analysis revealed the SSuT gene cluster region (approximately 13 kb) harboring genes encoding resistance to streptomycin (strA and strB), sulfonamide (sul2), and tetracycline (tetB, tetC, tetD, and tetR).

Impact of Dermanyssus gallinae infestation on persistent outbreaks of fowl typhoid in commercial layer chicken farms.

Although it has rapidly decreased since the early 2000s, fowl typhoid still occurs in commercial layer chickens, causing a significant economic loss in Korea. There is growing concern about the emergence of new pathogenic strains of the causative agent, Salmonella Gallinarum, which is able to overcome vaccine immunity. It has also been suspected that the poultry red mite, Dermanyssus gallinae, which is commonly found in layer chicken farms, may be an important cause of the recurrence of fowl typhoid in the farms.

High prevalence and variable fitness of fluoroquinolone-resistant avian pathogenic isolated from chickens in Korea.

Colibacillosis caused by avian pathogenic (APEC) is the most common bacterial disease in poultry, resulting in significant economic losses. Resistance to fluoroquinolones has been found to be high in APEC worldwide, which has increased concerns about risks to human health as well as poultry production. In the present study, we determined the prevalence, genetic traits, and fitness traits of fluoroquinolone-resistant APEC isolated from chickens in Korea using a total of 286 APEC isolates collected between 2014 and 2017.

Genotypic divergence of isolates with different growth requirements for nicotinamide adenine dinucleotide.

In 2017, for the first time in Asia, we reported the isolation of variants of with atypical NAD dependency. The present study was conducted to characterize the genotypes of 24 isolates of in Korea, including the four variants reported previously. Most of the typical isolates (19/20) showed a unique ERIC-PCR pattern with no ERIC-PCR patterns in common between the typical isolates and the variants.

Sequential Transmission of Salmonella in the Slaughtering Process of Chicken in Korea.

Salmonella is one of the most common foodborne pathogens worldwide. Salmonella infections in humans are mainly associated with consumption of poultry products contaminated with this foodborne pathogen. Therefore, strict sanitary measures are necessary to control Salmonella contamination during the slaughtering process of poultry.

Isolation and characterization of Avibacterium paragallinarum with different nicotinamide adenine dinucleotide requirements.

Twenty field isolates of Avibacterium paragallinarum were obtained from chickens in South Korea during 2011-2015. The isolates were identified by a HPG-2 PCR assay specific for A. paragallinarum and by biochemical tests.

Prevalence of Campylobacter species in wild birds of South Korea.

Campylobacter species cause human gastrointestinal infections worldwide. They commonly inhabit intestines of avian species including wild birds. They might play a role in the spread of infections to humans and other bird species.

Multiple novel H5N6 highly pathogenic avian influenza viruses, South Korea, 2016.

We report the identification of novel highly pathogenic avian influenza viruses of subtype H5N6, clade 2.3.4.

Public health significance of major genotypes of Salmonella enterica serovar Enteritidis present in both human and chicken isolates in Korea.

Salmonella enterica serovar Enteritidis is one of the most common serotypes implicated in Salmonella infections in both humans and poultry worldwide. It has been reported that human salmonellosis is mainly associated with the consumption of poultry products contaminated with serovar Enteritidis. The present study was to extensively analyze the public health risk of serovar Enteritidis isolates from chickens in Korea.

Comparison of the Antimicrobial and Sanitizer Resistance of Salmonella Isolates from Chicken Slaughter Processes in Korea.

Salmonella is a foodborne pathogen worldwide. Outbreaks of Salmonella are commonly associated with consumption of contaminated foods such as poultry products. Therefore, the objective of this study was to determine the occurrence, biofilm formation, antibiotic resistance, and sanitizer resistance of Salmonella enterica isolated from chicken carcasses.

Plasmid-Mediated Quinolone Resistance in Escherichia coli Isolates from Wild Birds and Chickens in South Korea.

A total of 2,423 nonduplicate isolates of Escherichia coli recovered from wild birds (n=793) and chickens (n=1,630) in South Korea were investigated for plasmid-mediated quinolone resistance (PMQR) genes. Altogether, 56 isolates with PMQR genes were identified, including 25 (3.2%) from wild birds and 31 (1.

Prevalence and characteristics of Salmonella spp. isolated from commercial layer farms in Korea.

Salmonellosis is one of the most prevalent foodborne illnesses. The outbreak of this disease is often associated with eggs. In this study, the prevalence and characteristics of Salmonella was surveyed in layer farms in Korea.

Arthritis in an egret (Egretta intermedia) caused by Salmonella Typhimurium and its potential risk to poultry health.

A dead Intermediate Egret (Egretta intermedia) was found on the shore of a stream in South Korea in January 2013. Salmonella Typhimurium was isolated from purulent exudates in the foot joints, demonstrating bacterial arthritis. The isolate was similar to a poultry isolate determined by pulsed-field gel electrophoresis.

SYBR green-based real-time reverse transcription-PCR for typing and subtyping of all hemagglutinin and neuraminidase genes of avian influenza viruses and comparison to standard serological subtyping tests.

Continuing outbreaks of H5N1 highly pathogenic (HP) avian influenza virus (AIV) infections of wild birds and poultry worldwide emphasize the need for global surveillance of wild birds. To support the future surveillance activities, we developed a SYBR green-based, real-time reverse transcriptase PCR (rRT-PCR) for detecting nucleoprotein (NP) genes and subtyping 16 hemagglutinin (HA) and 9 neuraminidase (NA) genes simultaneously. Primers were improved by focusing on Eurasian or North American lineage genes; the number of mixed-base positions per primer was set to five or fewer, and the concentration of each primer set was optimized empirically.

Field application of the H9M2e enzyme-linked immunosorbent assay for differentiation of H9N2 avian influenza virus-infected chickens from vaccinated chickens.

Vaccination for control of H9N2 low-pathogenicity avian influenza (LPAI) in chickens began in 2007 in South Korea where the H9N2 virus is prevalent. Recently, an enzyme-linked immunosorbent assay (ELISA) using the extracellular domain of the M2 protein (M2e ELISA) was developed as another strategy to differentiate between vaccinated and infected chickens. Here, an ELISA using the extracellular domain of the M2 protein of H9N2 LPAI virus (H9M2e ELISA) was applied to differentiate infected from vaccinated chickens using the H9N2 LPAI virus M2 peptide.

Genetic characterization of H1 avian influenza viruses isolated from migratory birds and domestic ducks in Korea.

H1 avian influenza viruses (AIVs) isolated from migratory birds and domestic ducks from 2003 to 2007 were analyzed to determine their genetic relationship. Phylogenic analysis with nucleotide sequences of all eight gene segments showed that 13 H1 AIVs from migratory birds and domestic ducks belonged to Eurasian avian lineages and were closely related to each other. Compared with H1 influenza viruses of swine or human origin in Korea, there was no evidence of reassortment among the human, swine, and avian hosts.

DNA barcoding techniques for avian influenza virus surveillance in migratory bird habitats.

Avian influenza virus (AIV) circulates among free-ranging, wild birds. We optimized and validated a DNA barcoding technique for AIV isolation and host-species identification using fecal samples from wild birds. DNA barcoding was optimized using tissue and fecal samples from known bird species, and the method was shown to distinguish 26 bird species.

Continuing evolution and interspecies transmission of influenza viruses in live bird markets in Korea.

Live bird markets (LBMs) provide an ideal environment for the evolution and interspecies transfer of avian influenza viruses (AIVs). In this study, we analyzed AIVs present in LBMs in Korea during the winter seasons of 2006-08. Sixty-five AIVs that belong to four hemagglutination (HA) subtypes ofAIV (H3, H4, H6, and H9) were isolated from 644 pooled tissue or swab samples collected in LBMs.

Application of DNA barcoding technique in avian influenza virus surveillance of wild bird habitats in Korea and Mongolia.

In a previous study, we optimized DNA barcoding techniques for avian influenza virus (AIV) isolation and host identification, using fecal samples from wild birds, for high-throughput surveillance of migratory waterfowls. In the present study, we surveyed AIV in Mongolia during the breeding season and, subsequently, in Korea in winter, to compare prevalent AIV subtypes and hosts using DNA barcoding. In Korea, H4 and H5 subtypes were the most abundantly detected HA subtypes, and most AIVs were isolated from the major population (mallards, Anas platyrhynchos) of wild bird habitats.

Validation of egg yolk antibody based C-ELISA for avian influenza surveillance in breeder duck.

Active surveillance for avian influenza virus (AIV) has expanded from chicken to various poultry species including duck. To further effective antibody screening in laying breeder ducks, we validated the egg yolk antibody as alternative source to serum for AIV antibody. Sera and eggs were collected at weekly intervals after two types of AIV vaccination, H5N3 and H9N2.

Evaluation of a competitive ELISA for antibody detection against avian influenza virus.

Active serologic surveillance is necessary to control the spread of the avian influenza virus (AIV). In this study, we evaluated a commercially-available cELISA in terms of its ability to detect AIV antibodies in the sera of 3,358 animals from twelve species. cELISA detected antibodies against reference H1- through H15-subtype AIV strains without cross reactivity.

Pathogenicity and transmission studies of H7N7 avian influenza virus isolated from feces of magpie origin in chickens and magpie.

An H7N7 avian influenza virus [A/Magpie/Kr/YJD174/07 (H7N7); Mp/Kr/07 virus] was isolated from magpie feces in the north-western area (Youngjongdo) of South Korea and identified as low pathogenicity by intravenous pathogenic index and amino acid sequence of cleavage site. In genetic analysis, the genome of the Mp/Kr/07 virus was the same as those of two other H7N7 viruses isolated from the Mallard ducks in Ganghwa, 5 km north of Youngjongdo, and grouped under the H7-subtype Eurasian linage with the highest similarity to recent two domestic duck isolates in South Korea. In vivo studies of the chickens and magpies, the Mp/Kr/07 virus, though did not caused any clinical signs with histological changes, could replicate in the oropharynx and cloaca of the chickens and was efficiently transmitted to contact chickens.

An outbreak of highly pathogenic H5N1 avian influenza in Korea, 2008.

In spite of intensive surveillance programs for the control of HPAI, an outbreak of highly pathogenic avian influenza (HPAI) H5N1 in Korea in April 2008 caused serious damage to poultry farms, as did previous outbreaks in 2003/2004 and 2006/2007. Six viruses were selected from the Korean 2008 isolates for genetic analysis, and all eight gene segments from each of the influenza viruses were sequenced. A phylogenetic analysis showed that all of the viruses were of the same virus type and that the hemagglutinin (HA) gene was clustered with that of clade 2.