Coding-complete genome sequence and phylogenetic analysis of Coxsackievirus B3 isolated from South Korea.

Whole-genome sequencing of a Coxsackievirus B3 strain isolated from the stool of a febrile patient with aseptic meningoencephalitis, South Korea, in 2002 was performed. This strain exhibits a high nucleotide sequence identity with various strains circulating in China from 2001 to 2019.

Risk factors associated with Coxiella burnetii in wild boars: A study in South Korea.

Coxiella burnetii is a Gram-negative bacterium that causes the zoonotic disease Q fever. Wild boars serve as reservoirs for C. burnetii. This study aimed to identify the risk factors associated with C. burnetii infection in wild boars. We analyzed the data from 975 wild boar samples collected from June to November 2021 in South Korea. We utilized the indirect ELISA to detect antibodies against C. burnetii. A sample optical density to positive-control optical density value exceeding 50% was classified as positive. We gathered data on the forestation, terrain, weather, agriculture, and animal density of the region where the samples were collected. Continuous variables were categorized into tertiles. We performed a univariate logistic regression analysis and included variables with a p-value < 0.2 in the final multivariable logistic regression model. In our multivariable logistic regression analysis to identify risk factors for C. burnetii infection in wild boars, we used a forward selection method to enter variables based on the order of their significance. We performed the final multivariable logistic regression analyses using either continuous variables or variables categorized into tertiles. The prevalence of C. burnetii was 14.6% (n=142). Locations with the highest maximum wind speeds (3.92-8.24 m/s) showed a 59% increase in infection odds compared to locations with the lowest speeds (1.45-3.25 m/s)(p=0.044). For each 1 m/s increase in maximum wind speed, infection odds increased by 24.1% (p=0.037). Regions with the highest percentage of paddy fields per area (8.3-45%) showed a 76% increase in infection odds compared to regions with the lowest percentage (0-1.5%)(p=0.011). For each 1% increase in the proportion of paddy fields per area, infection odds increased by 3.3% (p=0.003). High maximum wind speed and a high percentage of paddy field were identified as significant risk factors for C. burnetii infection in wild boars.

Altered Metabolic Phenotypes and Hypothalamic Neuronal Activity Triggered by Sodium-Glucose Cotransporter 2 Inhibition.

BACKGRUOUND: Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are currently used to treat patients with diabetes. Previous studies have demonstrated that treatment with SGLT-2 inhibitors is accompanied by altered metabolic phenotypes. However, it has not been investigated whether the hypothalamic circuit participates in the development of the compensatory metabolic phenotypes triggered by the treatment with SGLT-2 inhibitors. METHODS: Mice were fed a standard diet or high-fat diet and treated with dapagliflozin, an SGLT-2 inhibitor. Food intake and energy expenditure were observed using indirect calorimetry system. The activity of hypothalamic neurons in response to dapagliflozin treatment was evaluated by immunohistochemistry with c-Fos antibody. Quantitative real-time polymerase chain reaction was performed to determine gene expression patterns in the hypothalamus of dapagliflozin-treated mice. RESULTS: Dapagliflozin-treated mice displayed enhanced food intake and reduced energy expenditure. Altered neuronal activities were observed in multiple hypothalamic nuclei in association with appetite regulation. Additionally, we found elevated immunosignals of agouti-related peptide neurons in the paraventricular nucleus of the hypothalamus. CONCLUSION: This study suggests the functional involvement of the hypothalamus in the development of the compensatory metabolic phenotypes induced by SGLT-2 inhibitor treatment.

Small interfering RNA (siRNA)-based therapeutic applications against viruses: principles, potential, and challenges.

RNA has emerged as a revolutionary and important tool in the battle against emerging infectious diseases, with roles extending beyond its applications in vaccines, in which it is used in the response to the COVID-19 pandemic. Since their development in the 1990s, RNA interference (RNAi) therapeutics have demonstrated potential in reducing the expression of disease-associated genes. Nucleic acid-based therapeutics, including RNAi therapies, that degrade viral genomes and rapidly adapt to viral mutations, have emerged as alternative treatments. RNAi is a robust technique frequently employed to selectively suppress gene expression in a sequence-specific manner. The swift adaptability of nucleic acid-based therapeutics such as RNAi therapies endows them with a significant advantage over other antiviral medications. For example, small interfering RNAs (siRNAs) are produced on the basis of sequence complementarity to target and degrade viral RNA, a novel approach to combat viral infections. The precision of siRNAs in targeting and degrading viral RNA has led to the development of siRNA-based treatments for diverse diseases. However, despite the promising therapeutic benefits of siRNAs, several problems, including impaired long-term protein expression, siRNA instability, off-target effects, immunological responses, and drug resistance, have been considerable obstacles to the use of siRNA-based antiviral therapies. This review provides an encompassing summary of the siRNA-based therapeutic approaches against viruses while also addressing the obstacles that need to be overcome for their effective application. Furthermore, we present potential solutions to mitigate major challenges.

Hymenobacter canadensis sp. nov., isolated from freshwater of the pond in Cambridge Bay, Canada.

A Gram-stain-negative, aerobic, reddish-coloured, rod-shaped and non-motile strain PAMC 29467T, was isolated from freshwater of the pond in Cambridge Bay, Canada. Strain PAMC 29467T was closely related to Hymenobacter yonginensis (98.1 % 16S rRNA gene similarity). Genomic relatedness analyses showed that strain PAMC 29467T is distinguishable from H. yonginensis based on average nucleotide identity (91.3 %) and digital DNA-DNA hybridization values (39.3 %). The major fatty acids (>10 %) of strain PAMC 29467T were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C15 : 0 iso, C16 : 1 ω5c and summed feature 4 (C17 : 1 iso l and/or anteiso B). The major respiratory quinone was menaquinone-7. The genomic DNA G+C content was 61.5 mol%. Strain PAMC 29467T was separated from the type species in the genus Hymenobacter by its distinct phylogenetic position and some physiological characteristics. As a result, a novel species is proposed, with the name Hymenobacter canadensis sp. nov. (type strain, PAMC 29467T=KCTC 92787T=JCM 35843T).

Epidemiology of Chuzan Virus Infection in Free-Ranging and Farmed Cervids in South Korea: A Seroprevalence Survey.

Chuzan virus is teratogenic in cattle and causes congenital abnormalities, such as hydranencephaly and cerebellar hypoplasia, in calves. Chuzan virus seroprevalence among free-ranging and farmed cervids in South Korea was found to be 4.4% (38/873), confirming exposure to this virus in cervids in South Korea.

Prevalence and associated risk factors for Lawsonia intracellularis infection in farmed rabbits: A serological and molecular cross-sectional study in South Korea.

Lawsonia intracellularis is the etiological agent of proliferative enteropathy, which is globally considered an important enteric disease in pigs and horses. Experimental studies suggest that the organism spreads by subclinical infection of many animals, including rabbits. Despite the importance of rabbits in the epidemiology of L. intracellularis, the extent of exposure to L. intracellularis in the rabbit population is poorly defined and remains unclear. The objective of this cross-sectional study was to investigate the seroprevalence and shedding of L. intracellularis in farmed rabbits. Furthermore, we aimed to identify risk factors associated with seropositivity. Sera from the rabbits were used to measure L. intracellularis-specific antibodies by immunoperoxidase monolayer assay, and rectal swabs were used to detect L. intracellularis DNA using a real-time PCR assay. Antibodies against L. intracellularis were detected in 12.3% of farms (20/163) and 6.3% of rabbits (49/774). Lawsonia intracellularis DNA in rectal swabs was detected in 3.8% of farms (6/156) and 1.2% of rabbits (8/667). The risk factor analysis showed that the presence of pigs or horses on the farm or the neighboring farm was associated with an increase in the risk of seropositivity (p < 0.05). We observed significantly increased odds of positivity for L. intracellularis in rabbits with a history of digestive trouble (diarrhea) on the farm during the 3 months before the samples were obtained (p < 0.05). Collectively, these findings demonstrated that L. intracellularis infection was evident among farmed rabbits and that rabbits might serve as an important reservoir for L. intracellularis epidemiology.

Increasing seroprevalence of Japanese encephalitis virus in even-toed hoofed mammals (Artiodactyla species) associated with an upsurge of human cases in South Korea.

OBJECTIVES: The annual incidence of Japanese encephalitis (JE) has increased markedly in South Korea since 2010. We hypothesized that this increase was associated with higher frequencies of JE virus in animals. METHODS: We analyzed 5201 serum samples collected from even-toed hoofed mammals (Artiodactyla species) across South Korea from 2008 to 2012 using a stratified two-stage probability approach. RESULTS: The highest annual incidence of human JE cases and deaths occurred in 2010. Cases increased from six (no deaths) in 2008-2009 to 26 cases (seven deaths) in 2010. The JE virus seroprevalence in deer and elk fawns increased from 2.4% in 2008 to 24.1% in 2009, and in wild boars, it increased from 19.3% to 55.0% in the same period, which preceded the surge of human cases. Furthermore, the seroprevalence in calves increased from 15.3% in 2008 to 35.8% in 2010, and that in lambs and goat kids, increased from 8.5% in 2009 to 26.2% in 2010, which coincided with the surge in humans. CONCLUSION: Our findings show that the increased incidence of human JE in South Korea was temporally associated with an increasing seroprevalence in the Artiodactyla species. Surveillance of sentinel animals may be useful to predict the emergence of JE in humans.

Role of cervids in the epidemiology of bovine ephemeral fever virus infection in the Republic of Korea: A cross-sectional retrospective study.

BACKGROUND: Bovine ephemeral fever (BEF) is a viral disease in cattle and buffaloes, with subclinical involvement in various ruminant species. OBJECTIVES: This study aimed to investigate bovine ephemeral fever virus (BEFV) transmission in deer in the Republic of Korea (ROK) and the potential risk factors associated with seropositivity. METHODS: We conducted a retrospective cross-sectional serological survey of neutralising antibodies against BEFV in cervid sera collected from the ROK. RESULTS: The seroprevalence of BEFV was estimated to be 10.8% (95% confidence interval [CI] = 8.5-14.1), demonstrating that exposure to this virus is prevalent among farmed and free-ranging cervids in the ROK. The results revealed that age class and geographic location affected seroprevalence. Older age and the presence of neighbouring ruminant farms were significant risk factors (odds ratio [OR] = 2.394, 95% CI = 1.195-4.796) and (OR = 1.533, 95% CI = 1.026-2.288), respectively. We also observed that the individual likelihood of positivity in the southern provinces was significantly higher than that in the northern provinces (OR = 1.744, 95% CI = 1.001-3.037). There were also significant differences in the seroprevalence of cervids between the western and eastern provinces (OR = 2.021, 95% CI = 1.047-3.900). Factors that were not significantly associated with BEFV antibody prevalence included herd size and species (p > 0.05). CONCLUSIONS: These results suggest that cervid species may serve as important reservoirs for the transmission of BEFV, highlighting the need for closer monitoring of BEFV infections in cervids in the ROK.

Evaluation of dogs (Canis familiaris) as an indicator of Japanese encephalitis (JE) outbreaks: A retrospective serological study in the Seoul metropolitan area around the 2010 resurgence of JE in the Republic of Korea.

Japanese encephalitis (JE) is a mosquito-borne zoonotic neurological disease caused by Japanese encephalitis virus (JEV). JEV is the most common cause of viral encephalitis in Southeast Asia and the Western Pacific Rim. The fatality rate due to JE can reach 25% and up to 50% of the patients who survive develop permanent neurological damage. The annual incidence of human JE markedly increased in the Republic of Korea (ROK) in 2010 but the reason for the reemergence of JE in the ROK has not been established. This study aimed to assess the extent of exposure of domestic dogs to JEV in the Seoul metropolitan area, one of the most populated areas in the world. This cross-sectional study serologically investigated the spread of JEV in the dog population. Using serum neutralization test, we examined 3597 serum samples collected from pet, shelter, stray, and farmed dogs in the Seoul metropolitan area from 2006 to 2012. JEV-neutralizing antibodies found in shelter, stray, and farmed dogs sampled in approximately 2010 demonstrated increased JEV circulation in the dog population during the 2010 resurgence of JE reported among humans in the ROK. Five out of 1102 pet dogs (0.5%) were found to be neutralizing antibodies against JEV and 24 of 719 shelter dogs (3.1%) were positive with a peak of 13.0% in 2010. In addition, 25 of 690 stray dogs (3.6%) were positive with a peak of 9.7% in 2009, a year before the 2010 resurgence of JE. Furthermore, 39 of 1086 farmed dogs (3.6%) were seropositive with a peak of 9.2% in 2009. We therefore suggest that monitoring dog populations for seroconversion or seropositive dogs within JEV-active endemic areas may be useful for identifying risk areas for JE outbreaks and that JEV activity in dogs can be an indicator as the harbingers of JEV in humans.

Seroprevalence and Epidemiological Risk Factors for Kasba Virus Among Sheep and Goats in South Korea: A Nationwide Retrospective Study.

Introduction: Kasba virus belongs to the Palyam serogroup of the Orbivirus genus and Reoviridae family. Kasba virus is the causative agent of many reproductive disorders in infected animals, which result in considerable economic losses, mainly in the cattle industry. The epidemiology of Kasba virus infection is poorly defined and remains unclear in South Korea. Material and Methods: This study investigated the prevalence of antibodies against Kasba virus in sheep and goats in South Korea. Individual, management, and regional risk factors associated with seropositivity were also evaluated. In addition, a retrospective serosurvey was conducted. Results: Serum samples from 28 out of 441 sheep or goat flocks (6.3%, 95% confidence interval (CI): 4.4-9.0%) and 115 out of 1003 animals (11.5%, 95% CI 9.6-13.6%) were positive for antibodies against Kasba virus. According to our results, a history of reproductive problems increased the probability of Kasba virus positivity. Preventive measures such as routine insecticide application decreased this probability. We observed significant differences in the prevalence of seropositivity between southern provinces and northern provinces and between western provinces and eastern provinces at the individual level. Conclusion: The virus was widely distributed among sheep and goats in South Korea, with seropositivity ranging from 6.8% in 2004 to 13.7% in 2008. The current study represents the first assessment of factors associated with Kasba virus seroprevalence in sheep and goats in South Korea.

Hypothalamic TTF-1 orchestrates the sensitivity of leptin.

OBJECTIVE: Thyroid transcription factor-1 (TTF-1), a homeodomain-containing transcription factor, is predominantly expressed in discrete areas of the hypothalamus, which acts as the central unit for the regulation of whole-body energy homeostasis. Current study designed to identify the roles of TTF-1 on the responsiveness of the hypothalamic circuit activity to circulating leptin and the development of obesity linked to the insensitivity of leptin. METHODS: We generated conditional knock-out mice by crossing TTF-1flox/flox mice with leptin receptor (ObRb)Cre or proopiomelanocortin (POMC)Cre transgenic mice to interrogate the contributions of TTF-1 in leptin signaling and activity. Changes of food intake, body weight and energy expenditure were evaluated in standard or high fat diet-treated transgenic mice by using an indirect calorimetry instrument. Molecular mechanism was elucidated with immunohistochemistry, immunoblotting, quantitative PCR, and promoter assays. RESULTS: The selective deletion of TTF-1 gene expression in cells expressing the ObRb or POMC enhanced the anorexigenic effects of leptin as well as the leptin-induced phosphorylation of STAT3. We further determined that TTF-1 inhibited the transcriptional activity of the ObRb gene. In line with these findings, the selective deletion of the TTF-1 gene in ObRb-positive cells led to protective effects against diet-induced obesity via the amelioration of leptin resistance. CONCLUSIONS: Collectively, these results suggest that hypothalamic TTF-1 participates in the development of obesity as a molecular component involved in the regulation of cellular leptin signaling and activity. Thus, TTF-1 may represent a therapeutic target for the treatment, prevention, and control of obesity.

Factors associated with seropositivity to Aino virus among sheep and goats in South Korea.

Aino virus infection is responsible for epizootic and/or sporadic outbreaks of abortions, stillbirths and premature delivery among pregnant ruminants. The epizootiology of Aino virus infection is poorly defined in South Korea, therefore our aim was to assess its seroprevalence among sheep and goats. We also wanted to evaluate management and regional risk factors that might influence the frequency of infection. Between 2012 and 2013, 26 of 331 flocks (7.9%) and 139 of 915 heads (15.2%) were found serologically positive. In 2018, when samples were again collected in the same regions, 35 of 308 flocks (11.4%) and 89 of 735 heads (12.1%) showed serum-neutralising antibodies against Aino virus. Our results revealed that the age class and history of reproductive problems in the flocks are connected to an increased risk of being positive. The management risk factor attributes showed that preventive measures, such as the routine application of insecticide in farms, decreased the odds for seropositivity to Aino virus (OR = 0.453, P = 0.001). We observed a significant difference in the individual likelihood of being positive in the southern and western provinces with respect to that in the northern and eastern provinces, respectively (OR = 2.199, P < 0.001 and OR = 2.177, P < 0.001). The results of this study may serve as a basis for future epizootic studies on Aino virus infection in South Korea.

Metabolic reprogramming as a novel therapeutic target for Coxsackievirus B3.

Coxsackievirus B3 (CVB3) is a single-stranded RNA virus that belongs to the Enterovirus genus. CVB3 is a human pathogen associated with serious conditions such as myocarditis, dilated cardiomyopathy, and pancreatitis. However, there are no therapeutic interventions to treat CVB3 infections. In this study, we found that CVB3 induced metabolic alteration in host cells through increasing glycolysis level, as indicated by an increase in the extracellular acidification rate (ECAR). CVB3-mediated metabolic alteration was confirmed by metabolite change analysis using gas chromatography-mass spectrometry (GC-MS). Based on findings, a strategy to inhibit glycolysis has been proposed to treat CVB3 infection. Indeed, glycolysis inhibitors (2-Deoxy-D-glucose, sodium oxide) significantly reduced CVB3 titers after CVB3 infection, indicating that glycolysis inhibitors can be used as effective antiviral agents. Taken together, our results reveal a novel mechanism by which CVB3 infection is controlled by regulation of host cell metabolism.

Seroepidemiology of Aino Virus in Farmed and Free-Ranging Cervids in the Republic of Korea.

Aino virus is an infectious, non-contagious, vector-borne agent that has been implicated in arthrogryposis-hydranencephaly syndrome in newborn cattle, sheep, and goats. Information about reservoirs and host animal species susceptible to Aino virus remains unclear. To further explore the role of cervids in Aino virus infection transmission, we investigated cervid sera to determine the prevalence of Aino virus-neutralizing antibodies and to identify factors correlated with antibody positivity. We screened cervid serum samples collected in the Republic of Korea to better understand infection patterns in this animal species. Overall, Aino virus infection was widespread; 75 of 716 (10.5%, 95% [95% CI] = 8.4-13.4) farmed-cervid serum samples collected from 292 herds contained antibodies to Aino virus. Serological evidence of Aino virus infection was demonstrated in 5 of 43 free-ranging cervids, accounting for a prevalence rate of ~11.6% (95% CI = 4.6-26.4). Our results revealed that age class and geographic location affected seroprevalence. The main risk factors associated with Aino virus seroprevalence were older age (> 2 years old, OR = 2.221, 95% CI = 1.209-4.079, P = 0.009 in adults), southern provinces (OR = 2.432, 95% CI = 1.445-4.093, P = 0.001), and western provinces (OR = 1.905, 95% CI = 1.041-3.488, P = 0.034). The results in this study suggest that cervid species might serve as important hosts for the transmission of Aino virus, highlighting the need for careful monitoring of Aino virus infections in cervids.

Radicicol Inhibits Chikungunya Virus Replication by Targeting Nonstructural Protein 2.

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes a debilitating febrile illness characterized by persistent muscle and joint pain. The widespread distribution of transmission-competent vectors, Aedes species mosquitoes, indicates the potential risk of large-scale epidemics with high attack rates that can severely impact public health globally. Despite this, currently, there are no antivirals available for the treatment of CHIKV infections. Thus, we aimed to identify potential drug candidates by screening a chemical library using a cytopathic effect-based high-throughput screening assay. As a result, we identified radicicol, a heat shock protein 90 (Hsp90) inhibitor that effectively suppressed CHIKV replication by blocking the synthesis of both positive- and negative-strand viral RNA as well as expression of viral proteins. Interestingly, selection for viral drug-resistant variants and mutational studies revealed nonstructural protein 2 (nsP2) as a putative molecular target of radicicol. Moreover, coimmunoprecipitation and in silico modeling analyses determined that G641D mutation in the methyltransferase (MT)-like domain of nsP2 is essential for its interaction with cytoplasmic Hsp90ß chaperone. Our findings collectively support the potential application of radicicol as an anti-CHIKV agent. The detailed study of the underlying mechanism of action further contributes to our understanding of virus-host interactions for novel therapeutics against CHIKV infection.

Adiponectin Controls Nutrient Availability in Hypothalamic Astrocytes.

Adiponectin, an adipose tissue-derived hormone, plays integral roles in lipid and glucose metabolism in peripheral tissues, such as the skeletal muscle, adipose tissue, and liver. Moreover, it has also been shown to have an impact on metabolic processes in the central nervous system. Astrocytes comprise the most abundant cell type in the central nervous system and actively participate in metabolic processes between blood vessels and neurons. However, the ability of adiponectin to control nutrient metabolism in astrocytes has not yet been fully elucidated. In this study, we investigated the effects of adiponectin on multiple metabolic processes in hypothalamic astrocytes. Adiponectin enhanced glucose uptake, glycolytic processes and fatty acid oxidation in cultured primary hypothalamic astrocytes. In line with these findings, we also found that adiponectin treatment effectively enhanced synthesis and release of monocarboxylates. Overall, these data suggested that adiponectin triggers catabolic processes in astrocytes, thereby enhancing nutrient availability in the hypothalamus.

Serological evidence of bluetongue virus infection and serotype distribution in dairy cattle in South Korea.

BACKGROUND: Bluetongue is a vector-borne viral disease, and bluetongue virus (BTV) outbreaks can cause substantial economic losses. Even subclinical infection may carry significant associated costs, including a loss of condition, reduced milk yield, and infertility and abortion, and indirect costs, largely due to the export restrictions and surveillance requirements imposed to limit the spread of the virus. However, the BTV epidemiology in the Far East remains incompletely understood, especially in the cattle population in South Korea. In this study, the seroprevalence of BTV antibodies and distribution of BTV serotypes in dairy cattle in South Korea were evaluated to improve the understanding of the BTV epidemiological situation in the Asia-Pacific region. RESULTS: Between 2012 and 2013, a total of 37 out of 171 dairy cattle herds (21.6%) and 85 out of 466 dairy cattle heads (18.2%) showed antibodies against BTV. Neutralizing antibodies to BTV-1, - 2, - 3, - 4, - 7, - 15, and - 16 serotypes were identified, and the RNAs of the BTV-1, - 2, - 3, - 15, and - 16 serotypes were detected, indicating that BTV was circulating in the dairy cattle population in South Korea. CONCLUSIONS: These findings indicate that BTV is widespread and has circulated in dairy cattle in South Korea. This is the first report presenting evidence of circulating antibodies against BTV and the serotype distribution in bovine populations in South Korea.

Evidence of bluetongue virus circulation in farmed and free-ranging cervids from the Republic of Korea: A retrospective cross-sectional study.

Bluetongue, which is caused by bluetongue virus (BTV), is a vector-borne viral disease that affects wild and domestic ruminants. Trade restrictions can have a devastating impact in areas where BTV is endemic, regardless of the incidence of clinical disease. Currently, little is known about the prevalence of BTV infection in the Republic of Korea (ROK), and limited data on the BTV situation in the ROK are available. In this study, an epidemiological survey of BTV infection in farmed and free-ranging cervids from the ROK was conducted by a countrywide retrospective cross-sectional study. In total, BTV infection was widespread in the ROK, as 74 of 790 (9.4%, 95% confidence interval = 7.5-11.6%) cervid sera samples collected from 318 herds contained antibodies to BTV. Additionally, 42 herds evaluated in this study contained BTV seropositive cervids (13.2%). Serological evidence of bluetongue virus infection was observed in 17 of 158 free-ranging cervid animals, which accounts for the prevalence rate of approximately 10.8% (17/158; 95% CI = 6.8-16.6). Neutralizing antibodies to BTV-1, -2, -4, -7, and -15 serotypes were identified and RNAs of the BTV-1, -7, and -15 serotypes were detected, indicating that BTV was circulating in the cervids in ROK. These results suggest that cervids were actively exposed to BTV in the ROK and these species might serve as an important reservoir for the transmission of BTV. This is the first report on the evidence of circulating antibodies against BTV and serotype distribution in cervids in the ROK.