The Impact of Genetic Variation on Duck Hepatitis A Virus (DHAV) Vaccine Efficacy: A Comparative Study of DHAV-1 and DHAV-3 Against Emerging Variant Strains.

Duck virus hepatitis (DVH), caused by duck hepatitis A virus (DHAV), poses significant challenges to duck farming due to high mortality rates in young ducklings. Despite the widespread use of live attenuated vaccines, the genetic diversity within DHAV strains has diminished their cross-protection efficacy. This study aimed to evaluate the cross-protective efficacy of current DHAV-1 and DHAV-3 vaccines against genetically divergent wild strains.

Epidemiological Investigation and Genetic Analysis of Duck Circovirus in Korea from 2013 to 2022.

Duck circovirus (DuCV) infections cause immunosuppression in ducks, potentially leading to significant economic losses for the duck farming industry. This study investigates the prevalence, genetic characteristics, and evolutionary trends of DuCV in Korea between 2013 and 2022. Samples from 184 farms across seven provinces were analyzed using polymerase chain reaction (PCR).

Lack of Serological and Molecular Evidence of Duck Tembusu Virus Infection in Ducks from South Korea.

The duck Tembusu virus (DTMUV), an emerging flavivirus, has led to severe neurological disorders and substantial economic losses in the duck industry throughout Asia. Considering South Korea's increasing duck production and its strategic location along the East Asian-Australasian Flyway, this study aimed to assess the presence of DTMUV in South Korea to evaluate potential risks to the poultry industry. We performed a comprehensive serological survey of 1796 serum samples from broiler and breeder ducks collected between 2011 and 2023, alongside molecular detection tests on 51 duck flocks exhibiting suspected clinical signs of DTMUV infection.

Complete genome sequence of the avian paramyxovirus serotype 9 strain duck/Miyazaki/128/2021.

Here, we report the complete genome sequence of the avian paramyxovirus serotype 9 strain duck/Miyazaki/128/2021, which was determined using the Illumina MiSeq platform. The position of the hemagglutinin-neuraminidase stop codon differed from that of the only other available completely sequenced prototype strain, duck/New York/22/1977.

Establishment and Application of Mismatch Amplification Mutation Assay-PCR for Rapid Detection and Differentiation of Duck Hepatitis A Virus-1 Attenuated Vaccine and Wild Strains.

Duck hepatitis A virus type 1 (DHAV-1) is the main pathogen causing viral hepatitis in ducks, marked by high contagion and acute mortality. Live attenuated DHAV-1 vaccines are widely used to control the disease. This study aims to develop a mismatch amplification mutation assay (MAMA)-PCR for the rapid detection and differentiation of Korean DHAV-1 wild-type strains from vaccine strains.

Simultaneous construction strategy using two types of fluorescent markers for HVT vector vaccine against infectious bursal disease and H9N2 avian influenza virus by NHEJ-CRISPR/Cas9.

Recently, herpesvirus of turkeys (HVT), which was initially employed as a vaccine against Marek's disease (MD), has been shown to be a highly effective viral vector for producing recombinant vaccines that can simultaneously express the protective antigens of multiple poultry diseases. Prior to the development of commercial HVT-vectored dual-insert vaccines, the majority of HVT-vectored vaccines in use only contained a single foreign gene and were often generated using time-consuming and inefficient traditional recombination methods. The development of multivalent HVT-vectored vaccines that induce simultaneous protection against several avian diseases is of great value.

Development of a Highly Efficient CRISPR/Cas9-Mediated Herpesvirus of Turkey-Based Vaccine against Novel Variant Infectious Bursal Disease Virus.

Infectious bursal disease (IBD), caused by IBD virus (IBDV), is an extremely contagious immunosuppressive disease that causes major losses for the poultry industry worldwide. Recently, the novel variant IBDV (G2d) has been highly prevalent in Korea, but the current vaccines against this very virulent IBDV have limited efficacy against this novel variant. To develop a vaccine against this variant IBDV, a recombinant virus designated rHVT-VP2 was constructed by inserting the IBDV (G2d) VP2 gene into herpesvirus of turkeys (HVT) using CRISPR/Cas9 gene-editing technology.

Protection of Chickens against H9N2 Avian Influenza Isolates with a Live Vector Vaccine Expressing Influenza Hemagglutinin Gene Derived from Y280 Avian Influenza Virus.

Since the outbreak of the H9N2/Y439 avian influenza virus in 1996, the Korean poultry industry has incurred severe economic losses. A novel possibly zoonotic H9N2 virus from the Y280-like lineage (H9N2/Y280) has been prevalent in Korea since June 2020, posing a threat to the poultry sector. Rapid mutation of influenza viruses urges the development of effective vaccines against newly generated strains.

Comparative Studies of Antimicrobial Resistance in , , and Isolates from Broiler Chickens with and without Use of Enrofloxacin.

This study investigated the effect of enrofloxacin (ENR) administration on the prevalence and antimicrobial resistance of , , and isolated from broiler chickens under field conditions. The isolation rate of was significantly lower ( < 0.05) on farms that administered ENR (6.

Avian Reoviruses From Wild Birds Exhibit Pathogenicity to Specific Pathogen Free Chickens by Footpad Route.

Avian reoviruses (ARVs) are ubiquitous in domestic poultry with 80% of them being non-pathogenic and they are frequently found in clinically healthy birds. ARVs have also been known to be the etiological agents of viral arthritis (VA), tenosynovitis, myocarditis, runting-stunting syndrome (RSS), and respiratory and enteric disease in chickens. Significant economic losses during the process of poultry husbandry are due, in part, to unmitigated ARV infections throughout the poultry industry.

Isolation and Genomic Characterization of Avian Reovirus From Wild Birds in South Korea.

Avian reoviruses (ARVs) cause severe arthritis, tenosynovitis, pericarditis, and depressed growth in chickens, and these conditions have become increasingly frequent in recent years. Studies on the role of wild birds in the epidemiology of ARVs are insufficient. This study provides information about currently circulating ARVs in wild birds by gene detection using diagnostic RT-PCR, virus isolation, and genomic characterization.

Antimicrobial Resistance and PFGE Molecular Typing of serovar Gallinarum Isolates from Chickens in South Korea from 2013 to 2018.

Antimicrobial resistance and pulsed-field gel electrophoresis (PFGE) genotypes of collected ser. Gallinarum isolates were investigated to examine the epidemiological relationship between field outbreak isolates of ser. Gallinarum.

Evaluation of Safety and Protective Efficacy of a and Double Deletion Korean Epidemic Strain of Serovar Gallinarum.

With an aim to develop a highly attenuated and strongly immunogenic distinguishable vaccine candidate, a (a gene involved in the synthesis of lipopolysaccharide) and (a virulence gene) double deletion Korean epidemic strain of ser. Gallinarum (SG005) was constructed. Our results showed that the growth and biochemical characteristics were not altered by this double deletion.

Conjugative Plasmid-Mediated Extended Spectrum Cephalosporin Resistance in Genetically Diverse from a Chicken Slaughterhouse.

ESC-resistant isolates were collected from broiler chickens, a slaughterhouse, and retail meat to assess their dispersion and their involvement in cross-contamination. ESBL-/AmpC-producing were isolated during the slaughter process of all six investigated chicken flocks from scalding, feather removal, first conveyor, evisceration, second washing, third conveyor, and third washing areas, and from handling workers in the slaughterhouse. ESC-resistant isolates with the same pulsed-field gel electrophoresis type were found in the same site (scalding) on different sampling days.

Characterization of Extended-Spectrum Cephalosporin (ESC) Resistance in Isolated from Chicken and Identification of High Frequency Transfer of Gene Harboring Plasmid In Vitro and In Vivo.

A total of 136 isolates from chicken feces and meat samples of the top 12 integrated chicken production companies throughout Korea were collected. Among the 17 ESC-resistant ; was the most prevalent gene and two strains carried / and , respectively. The transferable gene was carried by IncFII plasmid in three isolates and the gene carried by IncI1 plasmid in one isolate.

Clonal dissemination of Salmonella enterica serovar albany with concurrent resistance to ampicillin, chloramphenicol, streptomycin, sulfisoxazole, tetracycline, and nalidixic acid in broiler chicken in Korea.

The aim of this study was to determine the prevalence, serovar distribution, antimicrobial resistance, and genotypic analyses of the dominating serovars of Salmonella in chickens from a national study in Korea. Between 2017 and 2018, a total of 550 chicken samples were collected from the top 12 integrated broiler chicken operations in Korea. Salmonella was isolated from 117 (32.

Genetic diversity of extended-spectrum cephalosporin resistance in Salmonella enterica and E. coli isolates in a single broiler chicken.

Extended-spectrum cephalosporin (ESC) resistance investigated in Salmonella and E. coli from the same chicken was to improve the understanding of the inter-species transmission of ESC resistance determinants in Salmonella and E. coli from a single chicken individual.

Transgenic Mice Overexpressing PG1 Display Corneal Opacity and Severe Inflammation in the Eye.

Antimicrobial peptides (AMPs) are of interest as alternatives to antibiotics or immunomodulators. We generated and characterized the phenotypes of transgenic mice overexpressing protegrin 1 (PG1), a potent porcine cathelicidin. No obvious differences were observed between PG1 transgenic and wild-type mice in terms of growth, development, general behaviour, and the major immune cell population.

Longitudinal Study of the Distribution of Antimicrobial-Resistant Isolates from an Integrated Broiler Chicken Operation.

The aim of this study was to analyze the prevalence, antimicrobial resistance, and genetic diversity of isolates that were obtained from whole chicken production stages in Korea. A total of 1348 samples were collected from 10 production lines. The prevalence of in breeder farm, broiler farm, slaughterhouse, and retail meat products was 50.

The Occurrence of Antimicrobial-Resistant in Hatcheries and Dissemination in an Integrated Broiler Chicken Operation in Korea.

Positive identification rates of in hatcheries and upstream breeder farms were 16.4% (36/220) and 3.0% (6/200), respectively.

Antimicrobial Susceptibility and Association with Toxin Determinants in Isolates from Chickens.

The aim of the present study was to investigate variation in antimicrobial resistance in () isolated from chickens after withdrawal of antimicrobial growth promoters (AGPs); and to investigate the correlation between the presence of toxin genes (, , and ) and antimicrobial resistance. Altogether, 162 isolates of were obtained from chickens displaying clinical signs of necrotic enteritis ( = 65) and from healthy chickens ( = 97) in Korea during 2010-2016. Compared to before AGP withdrawal, increased antimicrobial resistance or MIC/MIC value was observed for nine antimicrobials including penicillin, tetracycline, tylosin, erythromycin, florfenicol, enrofloxacin, monensin, salinomycin, and maduramycin.

Prevalence and potential risk of Salmonella enterica in migratory birds from South Korea.

Salmonella is a type of zoonotic bacteria that represents an economic and public health concern worldwide. Difficulties in sample collection from migratory birds mean little is known about their importance as a reservoir of Salmonella. The present study evaluated the prevalence and potential risk of Salmonella enterica in migratory birds.

The use of embryonic chicken eggs as an alternative model to evaluate the virulence of Salmonella enterica serovar Gallinarum.

Salmonella enterica serovar Gallinarum (S. Gallinarum) can cause fowl typhoid, a severe systemic disease responsible for considerable economic losses. Chicken pathogenicity test is the traditional method for assessing the virulence of S.

The novel cathelicidin of naked mole rats, Hg-CATH, showed potent antimicrobial activity and low cytotoxicity.

We performed the in silico genome-wide identification of antimicrobial peptides against the available genome sequence of the naked mole rat Heterocephalus glaber (H. glaber). Our results showed the presence of Hg-CATH, the single cathelicidin containing the antimicrobial domain in H.