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Background: Children spend a significant amount of time engaging in sedentary behaviors, defined as activities that do not increase energy expenditure significantly above resting levels, such as watching TV and playing PC/video games. Increased screen time is a significant public health concern because children are in a developmental stage where lifestyle behaviors predict various health outcomes in adulthood and beyond. This study explores the links between parent-child attachment, ego resilience, and children's screen time. Methods: This cross-sectional correlation study uses 1,163 parents and their children data from the 12th Panel Survey of Korean Children. The study instruments were a modified Armsden and Greenberg scale of parent-child attachment and modified the children's ego resilience scale of the Block and Kremen. Children's screen time was classified as more than 2 h per day spent watching television, playing on computers, or playing video games in their leisure time. Results: Study results show a negative association between father-child attachment and children's screen time (ß = -0.43, p <.001) and a positive association between father-child attachment and ego resilience (ß = 0.24, p <.001). Ego resilience showed a negative link to children's screen time after adjusting for parental attachment (ß =- 0.03, p =.009). Father-child attachment link to children's screen time (ß = -0.36, p <.001) continued even though the association was slightly reduced in magnitude after adjusting for ego resilience. Conclusions: Our findings show the mediating role of ego resilience on a negative path of father-child attachment to children's screen time. This finding emphasizes the importance of fostering solid father-child relationships and enhancing children's psychological resilience as critical strategies for reducing excessive screen time. By addressing emotional support and resilience-building, interventions can more effectively promote healthier behavioral outcomes in children. [ABSTRACT FROM AUTHOR]

Purpose: It is essential to investigate the users' needs in developing user-centered, family-based applications (apps) for managing childhood obesity. Methods: This study conducted focus group interviews with ten parents, ten children, and four app developers to investigate the need to develop a family-based mobile app for childhood obesity. The interview period was from July 17 to August 30, 2023. The data were analyzed using thematic analysis. Results: The results highlighted 31 key themes critical to family-based app development, including the need for comprehensive content promoting healthy lifestyle habits, tailored expert support, and motivational factors for app engagement, which were categorized as intrinsic, extrinsic, and social motivations and technological features. Participants also highlighted potential challenges, such as app usability issues and the need for a user-friendly interface. The pivotal role of parents in guiding and supporting their children's health behaviors was emphasized, particularly in creating a supportive environment that encourages sustained engagement with the app. Conclusion: These findings provide a comprehensive understanding of the needs and preferences of parents, children, and app developers in managing childhood obesity. Emphasis on integrating healthy lifestyle content, providing expert support, and incorporating motivational strategies is crucial for the app's success. Additionally, addressing potential difficulties and recognizing the pivotal role of parents are essential considerations. These insights will inform the design and development of a user-centered mobile app that supports families in managing childhood obesity. [ABSTRACT FROM AUTHOR]

Infectious bronchitis virus (IBV) causes a highly contagious respiratory disease in chickens, leading to significant economic losses in the poultry industry worldwide. IBV exhibits a high mutation rate, resulting in the continuous emergence of new variants and strains. A complete genome analysis of IBV is crucial for understanding its characteristics. However, it is challenging to obtain whole-genome sequences from IBV-infected clinical samples due to the low abundance of IBV relative to the host genome. Here, we present a novel approach employing next-generation sequencing (NGS) to directly sequence the complete genome of IBV. Through in silico analysis, six primer pairs were designed to match various genotypes, including the GI-19 lineage of IBV. The primer sets successfully amplified six overlapping fragments by long-range PCR and the size of the amplicons ranged from 3.7 to 6.4 kb, resulting in full coverage of the IBV genome. Furthermore, utilizing Illumina sequencing, we obtained the complete genome sequences of two strains belonging to the GI-19 lineage (QX genotype) from clinical samples, with 100% coverage rates, over 1000 × mean depth coverage, and a high percentage of mapped reads to the reference genomes (96.63% and 97.66%). The reported method significantly improves the whole-genome sequencing of IBVs from clinical samples; thus, it can improve understanding of the epidemiology and evolution of IBVs. [ABSTRACT FROM AUTHOR]

Photoporation techniques based on plasmonic nanoparticles such as gold nanoparticles have been extensively studied for the intracellular delivery of substances via cell membrane disruption. However, the clinical application of AuNP is challenging due to its absorption in the 500 nm region of the light spectrum. To overcome this challenge, upconversion nanoparticles were employed to stimulate AuNP at NIR wavelengths. posAuNP@UCNPs nanocomposites were produced by coating 30 nm UCNPs on 80 nm AuNPs using DOPA-PEI, which were then irradiated with 980 nm NIR light to facilitate their intracellular delivery. TEM and DLS confirmed that posAuNP and UCNP combine to form nanocomposites. Additionally, multiphysics simulation was used to analyze the distribution of the posAuNP electric field based on morphological differences that change as the UCNP ratio increases. Next, effective LED irradiation conditions were established by applying upconverting-photon quenching-mediated perforation influx to C28/I2 cells as suspensions or spheroids. posAuNP@UCNP nanocomposites were confirmed to be effective for the delivery of baricitinib as a treatment for osteoarthritis in a three-dimensional osteoarthritis model. Finally, chondrocyte differentiation was induced through intracellular delivery of baricitinib using posAuNP@UCNPs. The findings suggest that posAuNP@UCNPs have great potential as a tool for non-invasive drug delivery via UCPPin. [ABSTRACT FROM AUTHOR]

Budgerigar fledgling disease (BFD) is a contagious disease caused by avian polyomavirus (APV) in psittacine birds and causes high mortality rates. Here, eight APV-positive cases were confirmed from dead parrots or parrot tissue samples by polymerase chain reaction (PCR). Full-length genome sequencing showed high nucleotide identity (98.84–100%) between the APV strains. Phylogenetic analysis revealed that two genogroups were cocirculating in South Korea. The nucleotide sequences of five strains, collected from different parrot species, were identical; however, pathological lesions were observed in only two parrots, both aged 2 months. Pathology included necrotic spots in the liver, subcutaneous haemorrhage, hepatomegaly, ascites, intranuclear inclusion bodies, hepatocyte karyomegaly, hepatic necrosis, and bile duct proliferation. This suggests that the pathogenicity of APV might be host age-dependent regardless of the host species. This study improves our understanding of APV pathogenicity and provides a more detailed genetic characterization of APV strains. RESEARCH HIGHLIGHTS Eight APV strains were identified in South Korea from 2019 to 2021. By phylogenetic analysis, South Korean APV strains were classified into two clades. [ABSTRACT FROM AUTHOR]

Background: Thirty-two-day-old broiler chickens at a farm located in northwestern South Korea displayed adverse neurological symptoms including limping, lying down, and head shaking. Approximately 2.1% of chickens died or were culled due to severe symptoms. Five carcasses were submitted to the Avian Disease Division of the Animal and Plant Quarantine Agency (APQA) for disease diagnosis. Results: Broilers displayed severe pericarditis and perihepatitis associated with gross lesions. Broilers also displayed microscopic lesions in the cerebrum and in the granular layer of the cerebellum, which were associated with multifocal perivascular cuffing and purulent necrosis in the cerebrum, and severe meningitis with heterophil and lymphocyte infiltration. Staphylococcus spp. were identified in the liver and heart using bacteriological culture. PCR/RT-PCR assays revealed that broilers were negative for avian Clostridium botulinum, Newcastle disease virus, and avian encephalomyelitis virus. Bacterial and viral metagenomic analysis of brain sample further revealed the presence of Pseudomonas spp. and Marek's disease virus, which are known etiological agents of chicken meningoencephalitis. Conclusions: This study reports a diagnostic analysis of gross and histopathological lesions from 32-day-old broilers displaying unique neurological symptoms that revealed the presence of the several neurological diseases including meningoencephalitis. The causative agents associated with meningoencephalitis of broilers that had not been identified by routine diagnostic methods could be diagnosed by metagenomics, which proves the usefulness of metagenomics as a diagnostic tool for unknown neurological diseases in broilers. [ABSTRACT FROM AUTHOR]

Simple Summary: A male sandhill crane (Grus canadensis) was imported from the Netherlands in 2013 and bred for 8 years in a zoo for a crane-species restoration project in Gangwon Province in South Korea. The adult bird showed no clinical symptoms before its death. This study describes the anatomopathological finding of intrahepatic cholangiocarcinoma diagnosed in the captive sandhill crane, and metagenomic sequencing was performed to elucidate the etiology. This is the first report where the gross and histological characteristics of intrahepatic cholangiocarcinoma in a sandhill crane are described. No viral cause was identified in the metagenomics analysis and PCR of the cholangiocarcinoma sample, but a contributing role of Cutibacterium sp. and E. coli identified from the metagenomics could not be excluded. Tumors in birds can be caused by a variety of factors such as species, age, sex, virus, chemicals, and environment. In particular, tumors are a major cause of death in long-lived birds such as parrots and zoo birds. A male sandhill crane that was bred for 8 years in a zoo was diagnosed with intrahepatic cholangiocarcinoma (ICC). At necropsy, the liver revealed a multinodular mass of variable colors, and severe cirrhosis and hemorrhages were present. Histologically, ICC was characterized by the presence of both types of ICC: small-duct type and large-duct type. Large-duct-type ICC was distinguished by the presence of multifocal biliary neoplasia, characterized by the diffuse papillary proliferation of columnar cells resembling large cholangiocytes. Small-duct-type ICC was characterized by the presence of non-mucin-producing cuboidal cells such as bile duct cells. In this case, no viral cause was identified from the metagenomic analysis and PCR of ICC; however, a contributing role of Cutibacterium sp. and E. coli identified from the metagenomics could not be excluded. This study is the first to describe the anatomopathological characteristics of ICC in the studied sandhill crane and attempts to determine its potential infectious etiology using metagenomics. [ABSTRACT FROM AUTHOR]

Background: Thirty-two-day-old broiler chickens at a farm located in northwestern South Korea displayed adverse neurological symptoms including limping, lying down, and head shaking. Approximately 2.1% of chickens died or were culled due to severe symptoms. Five carcasses were submitted to the Avian Disease Division of the Animal and Plant Quarantine Agency (APQA) for disease diagnosis. Results: Broilers displayed severe pericarditis and perihepatitis associated with gross lesions. Broilers also displayed microscopic lesions in the cerebrum and in the granular layer of the cerebellum, which were associated with multifocal perivascular cuffing and purulent necrosis in the cerebrum, and severe meningitis with heterophil and lymphocyte infiltration. Staphylococcus spp. were identified in the liver and heart using bacteriological culture. PCR/RT-PCR assays revealed that broilers were negative for avian Clostridium botulinum, Newcastle disease virus, and avian encephalomyelitis virus. Bacterial and viral metagenomic analysis of brain sample further revealed the presence of Pseudomonas spp. and Marek's disease virus, which are known etiological agents of chicken meningoencephalitis. Conclusions: This study reports a diagnostic analysis of gross and histopathological lesions from 32-day-old broilers displaying unique neurological symptoms that revealed the presence of the several neurological diseases including meningoencephalitis. The causative agents associated with meningoencephalitis of broilers that had not been identified by routine diagnostic methods could be diagnosed by metagenomics, which proves the usefulness of metagenomics as a diagnostic tool for unknown neurological diseases in broilers. [ABSTRACT FROM AUTHOR]

Newcastle disease (ND) is a highly pathogenic viral infection of poultry with significant economic impacts worldwide. Despite the widespread use of vaccines, ND outbreaks continue to occur even within vaccinated poultry farms. Furthermore, novel Newcastle disease virus (NDV) genotypes are emerging in poultry, increasing the need for the development of rapid, accurate, and simple diagnostic methods. We therefore developed two novel sets of visual reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays based on highly conserved regions of the HN and F genes. The limits of detection of the NDV-Common-LAMP assay, for all the NDV strains, were 103.0 EID50/0.1 mL for Kr005 and 102.0 EID50/0.1 mL for Lasota within 35 min. The sensitivity of the NDV-Patho-LAMP assay, used for the strain differentiation of virulent NDV, was 102.0 EID50/0.1 mL for Kr005. No amplification was detected for the non-NDV templates. Next, we probed 95 clinical strains and 7 reference strains with the RT-LAMP assays to assess the feasibility of their use in diagnostics. We observed no cross-reactivity across the 102 strains. Furthermore, there was 100% congruence between the RT-LAMP assays and full-length sequencing of the target genes, indicating the potential for visual RT-LAMP in the identification and differentiation of NDV. These novel RT-LAMP assays are ideally suited for the field or resource-limited environments to facilitate the faster detection and differentiation of NDV, which can reduce or avoid further spread. [ABSTRACT FROM AUTHOR]

Background: Nurses have an essential role and responsibility to work at the forefront of patient care during the COVID-19 pandemic. Although the press and public have praised the dedication of nurses in the COVID-19 pandemic, there are several points to consider for nursing professional development. The purpose of this study is to collect the experiences of the nursing profession in the COVID-19 pandemic through interviews, seek improvements for the development of the nursing profession, and suggest directions for the future. Method: This qualitative study adopts semi-structured interviews analyzing the nursing experience of the COVID-19 pandemic based on the professional practice models (PPMs). Ten nurses with at least two years of working experience and thorough work changes in the COVID-19 pandemic from various settings have participated in the study. Results: We identified thirty-nine problematic codes and nineteen improvement codes which mapped to 12 key concepts and corresponded to 6 constructs of the PPM model. Conclusion: Nurses had to take on tasks beyond their duties in urgent situations, which restrained nurses from concentrating on their work. Clarifying working boundaries is fundamental for collaborative care and independent nursing practice. Collaboration and communication among healthcare workers based on mutual understanding can create a respectful working environment. Although there were many difficulties due to the uncertain situation, we can find that the nursing profession can make achievements through systematic and organizational support for sticking to the basics of nursing, securing technical expertise, cultivating critical thinking, and developing various professional attributes. In this way, the establishment of roles based on professional values and duties and the ascertainment of clear boundaries for nursing will ultimately help to improve the quality of patient care. [ABSTRACT FROM AUTHOR]

Infectious bursal disease (IBD), caused by IBD virus (IBDV), threatens the health of the poultry industry. Recently, a subtype of genogroup (G) 2 IBDV named G2d has brought a new threat to the poultry industry. To determine the current status of IBDV prevalence in South Korea, active IBDV surveillance on 167 randomly selected broiler farms in South Korea from August 2020 to July 2021 was conducted. The bursas of Fabricius from five chickens from each farm were independently pooled and screened for IBDV using virus-specific RT-PCR. As a result, 86 farms were found to be infected with the G2d variant, 13 farms with G2b, and 2 farms with G3. Current prevalence estimation of IBDV infection in South Korea was determined as 17.8% at the animal level using pooled sampling methods. G2d IBDV was predominant compared to other genogroups, with a potentially high-risk G2d infection area in southwestern South Korea. The impact of IBDV infection on poultry productivity or Escherichia coli infection susceptibility was also confirmed. A comparative pathogenicity test indicated that G2d IBDV caused severe and persistent damage to infected chickens compared with G2b. This study highlights the importance of implementation of regular surveillance programs and poses challenges for the comprehensive prevention of IBDV infections. [ABSTRACT FROM AUTHOR]

Simple Summary: This study describes the histopathological finding of mucosal papillary proliferation observed in the esophagus of chicken and attempts to determine its infectious etiology using metagenomics. Unlike squamous metaplasia of the esophageal mucosa due to vitamin A deficiency, the stratified squamous epithelial cells of the esophagus were completely replaced by increased numbers of ducts/ductules, lymphocytes, and connective tissue, and multiple hyperplasia of the esophageal gland was observed. As the result of the metagenomic analysis of esophagus samples from this chicken, no viral cause was identified; however, the contributing role of Bradyrhizobium sp. could not be excluded. In this study, we report the first histopathological examination of a rare case of an esophageal papillary lesion appearing as adenoma in a chicken and highlight the importance of histopathological results for a definitive diagnosis of such cases. White or pale-yellow nodules 2–7 mm in length were observed in the esophageal lumen in a number of laying broiler breeders with reduced laying rates. Metaplasia of the mucosal epithelial layer and mucous gland, as well as lymphocyte infiltration under the esophageal mucous gland and epithelial cell layer, were observed, which we found were caused by vitamin A deficiency. In one chicken, however, the stratified squamous epithelial cells of the esophagus were completely replaced by increased numbers of ducts/ductules, lymphocytes, and connective tissue, resulting in a papillary morphology. The ducts were surrounded by a fibrous stroma. Multiple hyperplasia of the esophageal gland was also observed and the esophageal glands were lined by a single layer of columnar cells, and a large number of lymphocytes were infiltrated into the submucosal layer. Based on the gross findings, this papillary proliferation was considered papilloma, but histopathologically, a mass composed of squamous epithelium was not observed. Therefore, the papillary lesion appeared as adenoma with squamous metaplasia of the esophageal gland and ectasia, or mucosal epithelial papillary hyperplasia, associated with chronic esophagitis. A metagenomic analysis of the esophagus samples from this chicken was performed to determine the infectious etiology. No viral cause was identified; however, a contributing role of Bradyrhizobium sp. could not be excluded. In this study, we report the first histopathological examination of a rare case of esophageal papillary proliferation in a chicken and highlight the importance of histopathological results for a definitive diagnosis of such cases. [ABSTRACT FROM AUTHOR]

Background: In July 2015, the carcasses of 11 cockatiels were submitted for disease diagnosis to the Avian Disease Division of the Animal and Plant Quarantine Agency of Korea. The cockatiels, which appeared dehydrated and underweight, had exhibited severe diarrhea and 22 % mortality over 2 weeks. Traditional diagnosis did not reveal the causes of these symptoms. Methods: We conducted metagenomics analysis on intestines and livers from the dead cockatiels using Illumina high-throughput sequencing. To obtain more accurate and longer contigs, which are required for further genetic characterization, we compared the results of three de novo assembly tools (metaSPAdes, MEGAHIT, and IDBA-UD). Results: Sequence reads of Campylobacter jejuni (C. jejuni) and Chlamydia psittaci (C. psittaci) were present in most of the cockatiel samples. Either of these bacteria could cause the reported symptoms in psittaciformes. metaSPAdes (ver.3.14.1) identified the 1152 bp flaA gene of C. jejuni and the 1096 bp ompA gene of C. psittaci. Genetic analysis revealed that flaA of C. jejuni was recombinant between C. jejuni and Campylobacter coli, and that ompA of C. psittaci isolated from cockatiel was closely related to strains isolated from humans. Conclusions: C. jejuni and C. psittaci were detected in cockatiels in the Republic of Korea using metagenomic analysis. This approach is useful for understanding pathogens of pet birds. Three de novo assemblers were compared to obtain accurate contigs from large quantities of reads, and sequences of C. jejuni and C. psittaci generated by metaSPAdes were analyzed. [ABSTRACT FROM AUTHOR]

Infectious bursal disease (IBD) is one of the most important immunosuppressive diseases of young chickens, causing considerable economic losses to the poultry industry. More than 30 years ago, an antigenic variant (av) pathotype of the IBD virus (IBDV) was reported to originate in, and subsequently spread among, poultry farms in the USA. Recently, a novel avIBDV lineage was identified in China and was shown to exhibit clear differences in its pathogenicity as well as molecular characteristics compared with the previously isolated variant strains. In this study, we conducted a passive surveillance of chicken carcasses submitted to our research division from June–December 2019, and detected the IBDV strains by reverse transcription PCR. Five avIBDV strains were isolated, and their pathogenicity was determined by necropsy and molecular analysis. Additionally, a coinfection field case involving an avIBDV strain and a very virulent IBDV (vvIBDV) strain was identified. Multiple sequence alignment and phylogenetic analysis of partial viral protein 1 (VP1) and hypervariable region (hv) VP2 genes revealed that those strains originated from two different avIBDV lineages. The co-occurrence of two sub-groups of avIBDVs in South Korea confirms for the first time the evolution of antigenic variant IBDV strains, and highlights the urgency for the development of new strategies for IBDV intervention in South Korea. RESEARCH HIGHLIGHTS Five avIBDV strains were identified in South Korea by passive surveillance test in 2019. A coinfection between two IBDV strains from different genogroups was reported in a field case. By phylogenetic analysis, Korean avIBDVs belonged to two distinct lineages of antigenic variant genogroup. [ABSTRACT FROM AUTHOR]

Background and aims: Runting-stunting syndrome (RSS) in chickens, also known as malabsorption syndrome, which is characterized by mild to severe enteritis and diagnosed through typical histopathologic examination as well as clinical signs, results in considerable economic losses. Despite the many studies carried out over decades to determine the etiologic agents of RSS involved in the disease, several outbreaks remained without the elucidation of, potentially multiple, etiologies involved. Methods: We performed comparative analysis of viral metagenomes from four chicken flocks affected with RSS using next-generation sequencing. Primers for the detection of chicken enteric viruses were designed from the sequencing data obtained with metagenomics. Multiplex reverse transcription–polymerase chain reaction (PCR) and PCR were performed to detect a variety of etiological agents previously described in natural cases of RSS. Results: The most abundant viral families identified in this study were Astroviridae, Picornaviridae, Parvoviridae, Caliciviridae, Reoviridae and Picobirnaviridae. Chicken astrovirus sequences were present in all four samples, suggesting an association between chicken astrovirus and RSS and chicken astrovirus as a candidate pathogen responsible for RSS. Picobirnavirus and the newly identified chapparvovirus were found in chickens in the Republic of Korea for the first time, and the genetic diversity of enteric viruses and viral communities was showed. Conclusions: Chicken astrovirus was consistently detected in broilers affected with RSS and the result of this study may contribute to knowledge of enteric diseases and viruses in chickens. [ABSTRACT FROM AUTHOR]

The management of cardiometabolic risk factors, such as abdominal obesity, dyslipidemia, hypertension, and hyperglycemia, is essential for the health of postmenopausal women. In this study, we identified the effects of autonomy-supportive, Web-based lifestyle modification for the management cardiometabolic risk of postmenopausal women, and assessed the mediation effect of intrinsic motivation. This study was a randomized trial involving 71 postmenopausal Korean women. For the intervention group, we provided the Web-based autonomy supports for 12 weeks; however, for the control group, individual consultations on healthy lifestyle was conducted at the first meeting. In the intervention group, cardiometabolic risks ameliorated as follows: waist circumference and waist-to-height ratio decreased by 3.9 cm and 0.03 cm, respectively; triglycerides decreased by 8.5 mg/dl; triglycerides-to-high-density-lipoprotein cholesterol ratio decreased by 0.21; systolic blood pressure decreased by 3.3 mmHg, and the visceral adiposity index decreased. Among the subdomain of intrinsic motivation, perceived competence, effort/importance, and perceived choice showed an association with waist circumference changes. Web-based autonomy supports can be effective in implementation and maintenance, and the amelioration of cardiometabolic risk in postmenopausal women. [ABSTRACT FROM AUTHOR]

Campylobacterspecies 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. The prevalence ofCampylobacterspecies in 2164 faecal samples of wild birds (representing 71 species and 28 families) captured across the Korean peninsula was evaluated in this study. The overall prevalence was 15.3% (332/2164). Bird species belonging to the familyCharadriidaehad the highest isolation rate (30.0%), followed by those belonging to the familiesArdeidae(26.4%),Turdidae(21.9%), andAnatidae(15.3%). The prevalence ofCampylobacterspp. differed significantly according to migratory habit. Stopover birds were the most commonly infected (19.0%), followed by winter migratory (16.7%) and summer migratory birds (12.3%). However, indigenous birds showed very low prevalence (2.7%). Antimicrobial susceptibility tests were performed for 213 isolates. Results showed thatCampylobacter jejuniisolates (n = 169) exhibited resistance to nalidixic acid (5.3%), ciprofloxacin (3.0%), and tetracycline (1.8%), whileCampylobacter lari(n = 1) displayed resistance to nalidixic acid and ciprofloxacin. However, allCampylobacter coliisolates (n = 20) were susceptible to all antimicrobials tested. This is the first report on the prevalence ofCampylobacterspecies in wild birds that seasonally or indigenously inhabit the Korean peninsula. Our results indicate that the overall prevalence ofCampylobacterin wild birds is moderate. Therefore, birds might serve as significant reservoirs forCampylobacterpathogens. [ABSTRACT FROM PUBLISHER]

We compared the clinical signs, histopathological lesions and distribution of viral antigens among infected young (meat-type) and older (breeder) ducks that were naturally infected with the highly pathogenic avian influenza (HPAI) virus during the 2010–2011 Korean outbreak. The meat-type ducks had a high mortality rate (30%) and showed severe neurological signs such as head tremors and paresis. In contrast, HPAI-infected breeder ducks had minimal clinical signs but a decreased egg production rate. The histopathological characteristics of infected meat-type ducks included necrotic lesions of heart and brain, which may have primarily contributed to the high mortality rate. In contrast, the breeder ducks only presented necrotic splenitis, and viral antigens were only detected in the trachea, lungs and spleen. Younger ducks had a high viral titre in the organs, high levels of viral shedding and a high mortality rate after experimental HPAI virus infection. Compared to the breeder ducks, the meat-type ducks were raised in smaller farms that had poor quarantine and breeding facilities. It is therefore possible that better biosecurity in the breeder farms could have reduced the infection dose and subsequently the severity of the disease. Thus, age and management may be the influencing factors for HPAI susceptibility in ducks. [ABSTRACT FROM AUTHOR]

Background: The rapid and accurate identification of the H5 and H7 subtypes of avian influenza (AI) virus is an important step for the control and eradication of highly pathogenic AI outbreaks and for the surveillance of AI viruses that have the potential to undergo changes in pathogenicity in poultry and wild birds. Currently, real-time reverse transcription polymerase chain reaction (RRT-PCR) is routinely used for the rapid detection of the H5 and H7 genes, but misidentification is frequent for emergent isolates and viruses isolated from diverse regions due to the high sequence variation among AI viruses. Findings: In this study, an RRT-PCR method was tested for the detection of matrix, H5 and H7 genes from diverse subtypes of AI viruses and from field samples obtained through AI surveillance in South Korea over the last four years. Both RRT-PCR and conventional experiment (virus isolation using egg inoculation followed by reverse transcription polymerase chain reaction) agreed on the virus-positive samples. And the comparison of the results with 174 clinical samples showed a high level of agreement without decreasing the specificity and sensitivity. Conclusions: This assay could be useful tool for the rapid detection of AI using the field samples from domestic poultry and wild birds in South Korea, and continuous regional updates is needed to validate primer sets as the AI virus evolves. [ABSTRACT FROM AUTHOR]

The hemagglutination inhibition (HI) assay is the standard diagnostic test for detection of antibodies to avian influenza viruses. It is well known that chicken serum does not require additional serum pretreatment to remove nonspecific inhibitors (NSIs). However, NSIs were recognized in certain Korean local breeds. In the present study, various treatments were compared to remove such NSIs. Heat treatment, red blood cell adsorption, and kaolin treatment did not remove NSIs effectively, and treatment with periodate only partly eliminated the NSIs. Receptor destroying enzyme (RDE) treatment appeared to effectively remove NSIs from chicken sera, regardless of breeds. It is proposed that RDE treatment should be included in the HI tests for serological diagnosis of avian Influenza A virus. [ABSTRACT FROM PUBLISHER]

Highly pathogenic avian influenza (H5N1) among wild birds emerged simultaneously with outbreaks in domestic poultry in South Korea during November 2010-May 2011. Phylogenetic analysis showed that these viruses belonged to clade 2.3.2, as did viruses found in Mongolia, the People's Republic of China, and Russia in 2009 and 2010. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza (H5N1) among wild birds emerged simultaneously with outbreaks in domestic poultry in South Korea during November 2010-May 2011. Phylogenetic analysis showed that these viruses belonged to clade 2.3.2, as did viruses found in Mongolia, the People's Republic of China, and Russia in 2009 and 2010. [ABSTRACT FROM AUTHOR]

Infectious bronchitis viruses (IBVs) are evolving continuously via genetic drift and genetic recombination, making disease prevention and control difficult. In this study, we undertook genetic and pathogenic characterization of recombinant IBVs isolated from chickens in South Korea between 2003 and 2019. Phylogenetic analysis showed that 46 IBV isolates belonged to GI-19, which includes nephropathogenic IBVs. Ten isolates formed a new cluster, the genomic sequences of which were different from those of reference sequences. Recombination events in the S1 gene were identified, with putative parental strains identified as QX-like, KM91-like, and GI-15. Recombination detection methods identified three patterns (rGI-19-I, rGI-19-II, and rGI-19-III). To better understand the pathogenicity of recombinant IBVs, we compared the pathogenicity of GI-19 with that of the rGI-19s. The results suggest that rGI-19s may be more likely to cause trachea infections than GI-19, whereas rGI-19s were less pathogenic in the kidney. Additionally, the pathogenicity of rGI-19s varied according to the genotype of the major parent. These results indicate that genetic recombination between heterologous strains belonging to different genotypes has occurred, resulting in the emergence of new recombinant IBVs in South Korea. [ABSTRACT FROM AUTHOR]