Chest Radiography of Tuberculosis: Determination of Activity Using Deep Learning Algorithm / 결핵및호흡기질환

Background@#Inactive or old, healed tuberculosis (TB) on chest radiograph (CR) is often found in high TB incidence countries, and to avoid unnecessary evaluation and medication, differentiation from active TB is important. This study develops a deep learning (DL) model to estimate activity in a single chest radiographic analysis. @*Methods@#A total of 3,824 active TB CRs from 511 individuals and 2,277 inactive TB CRs from 558 individuals were retrospectively collected. A pretrained convolutional neural network was fine-tuned to classify active and inactive TB. The model was pretrained with 8,964 pneumonia and 8,525 normal cases from the National Institute of Health (NIH) dataset. During the pretraining phase, the DL model learns the following tasks: pneumonia vs. normal, pneumonia vs. active TB, and active TB vs. normal. The performance of the DL model was validated using three external datasets. Receiver operating characteristic analyses were performed to evaluate the diagnostic performance to determine active TB by DL model and radiologists. Sensitivities and specificities for determining active TB were evaluated for both the DL model and radiologists. @*Results@#The performance of the DL model showed area under the curve (AUC) values of 0.980 in internal validation, and 0.815 and 0.887 in external validation. The AUC values for the DL model, thoracic radiologist, and general radiologist, evaluated using one of the external validation datasets, were 0.815, 0.871, and 0.811, respectively. @*Conclusion@#This DL-based algorithm showed potential as an effective diagnostic tool to identify TB activity, and could be useful for the follow-up of patients with inactive TB in high TB burden countries.

Temporal Trends and Characteristics of Adult Patients in Emergency Department Related to Suicide Attempt or Self-Harm in Korea, 2016–2020

Background@#The implementation of an effective suicide prevention program requires the identification and monitoring of subpopulations with elevated risks for suicide in consideration of demographic characteristics, to facilitate the development of tailored countermeasures for tackling the risk factors of suicide. We examined the annual trends in emergency department (ED) visits for suicide attempts (SAs) or self-harm and investigated the sex- and age-specific characteristics of individuals who visited the ED for SA and self-harm. @*Methods@#Data on ED visits for SAs or self-harm in Korea from 2016 to 2020 were extracted from the National Emergency Department Information System and assessed. We evaluated the age-standardized incidence rate of ED visits for SAs or self-harm, and hospital mortality among individuals who visited the ED for SAs or self-harm. In addition, the characteristics of the individuals were compared according to sex and age. @*Results@#We identified 145,963 ED visits for SAs or self-harm (0.42% of the total ED visits) during the study period. The rate of ED visits increased in the youngest age group (19–29 years old), and was more prominent among women (increased by an annual average of 22.5%), despite the coronavirus disease pandemic. The middle-aged group (45–64 years old) had a higher rate of mortality than other age groups, and the highest proportion of individuals on Medical Aid. @*Conclusion@#It is necessary to plan age- and gender-specific suicide prevention programs that focus on improving the limited public mental health resources for the vulnerable populations.

Building of Pediatric COVID-19 Module Clinic: A Novel Operation Model in Response to COVID-19 Pandemic

In mid-2022, as the wave of pediatric coronavirus disease 2019 (COVID-19) cases escalated in South Korea, a public-private partnership was made to establish a Pediatric COVID-19 Module Clinic (PMC). We describe the utilization of the first prototype children’s modular clinic in Korea University Anam Hospital functioning as the COVID-19 PMC. Between August 1 and September 30, 2022, a total of 766 children visited COVID-19 PMC. Daily number of patient visits to the COVID-19 PMC ranged between 10 and 47 in August; and less than 13 patients per day in September 2022. Not only the model provided timely care for the COVID-19 pediatric patients, but it also enabled safe and efficacious care for the non-COVID-19 patients in the main hospital building while minimizing exposure risk to severe acute respiratory syndrome coronavirus 2 transmission. Current description highlights the importance of spatial measures for mitigating in-hospital transmission of COVID-19, in specifically on pediatric care.

Clinical Efficacy and Safety of Endoscopic Treatment of Gastrointestinal Stromal Tumors in the Stomach

Background/Aims@#Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the stomach. We evaluated the clinical outcomes of endoscopic treatment for gastric GISTs. @*Methods@#This is a single center, retrospective study that enrolled 135 cases of gastric subepithelial tumors (SETs) resected by endoscopic procedures and confirmed as GISTs by histopathology from March 2005 to July 2019. The immediate and long-term clinical outcomes were analyzed retrospectively. @*Results@#The mean patient age was 57.9 years, and the mean tumor size was 2.1 cm. Of the tumors, 43.0% were located in the body, followed by the fundus (26.7%) and cardia (17.0%). Most tumors (85.2%) were resected by endoscopic submucosal dissection, followed by endoscopic mucosal resection (6.7%), submucosal tunneling endoscopic resection (5.9%), and endoscopic full-thickness resection (2.2%). Macroperforation occurred in 4.4% and microperforation in 6.7% of the cases. The R0 resection rate was 15.6%. However, the rate of complete resection by the endoscopic view was 90.4%, of which 54.8% of cases were in the very-low-risk group, followed by the low-risk group (28.1%), intermediate-risk group (11.9%), and high-risk group (5.2%). During 36.5 months of follow-up, recurrence was found in four (3.4%) of the 118 patients who were monitored for more than 6 months (low-risk group, 1/37 [2.7%]; intermediate-risk group, 2/11 [18.2%]; high-risk group, 1/6 [16.7%]). @*Conclusions@#Endoscopic treatment of a GIST appears to be a feasible procedure in selected cases. However, additional surgery should be considered if the pathologic results correspond to intermediate- or high-risk groups.

Syndromic Testing for Sexually Transmitted Infection: Current and Future Demand / 대한임상미생물학회지

Sexually transmitted infections (STIs) are a major global public health problem, with significant social burden worldwide. Accurate and appropriate diagnosis and treatment of STIs are important for preventing the transmission of STIs as well as major health consequences of untreated STIs, such as infertility and certain cancer. For diagnosis of STIs, the application of conventional culture and immunoassays is limited by their low sensitivity and long turnaround time. Nucleic acid amplification tests for STIs allow for syndromic tests for multiple pathogens simultaneously and show high sensitivity with a short turnaround time. In this review, we discuss the characteristics of commercially available multiplex molecular platforms and the features needed in next-generation syndromic tests for STIs.

Anti-inflammatory effects of ethanol extracts of the flower buds of Syzygium aromaticum L. on human gingival fibroblast cells treated with Porphyromonas gingivalis lipopolysaccharide / 대한치과재료학회지

This study was conducted to evaluate the cytotoxic and anti-inflammatory effects of the ethanol extract of Syzygium aromaticum L. (clove) buds. The cytotoxicity test was performed by cell counting method using hTERT-hNOF cells, a human immortalized gingival fibroblast cell line. To test the anti-inflammatory effects, the hTERT-hNOF cells were treated with lipopolysaccharide (LPS) extracted from Porphyromonas gingivalis KCOM 2804 (PgLPS) and ethanol extract of clove buds. The expression levels of PGE2, IL-6, and IL-8 were measured by enzyme-linked immunosorbent assay. The cytotoxicity test data showed a cell viability of ≧ 82% in hTERT-hNOF cells treated with 10 to 80 µg/mL of the ethanol extract of clove buds. The anti-inflammatory test data showed that the expression of PGE2 by PgLPS treatment was reduced to the level of the negative control group by treatment with 10 µg/mL or more of the ethanol extract of clove buds. In group treated with PgLPS and 40 µg/mL of clove bud ethanol extract, the expression levels of IL-6 and IL-8 in were inhibited by 75% and 77%, respectively (p<0.05), compared to the positive control (PgLPS treatment) group. These results suggest that the ethanol extract of clove buds can be used in developing oral hygine products for preventing periodontal disease.

Comparison of fiberoptic bronchoscopic intubation using silicone and polyvinyl chloride double-lumen tubes / 대한마취과학회지

Background@#Direct insertion of a double-lumen tube (DLT) using a flexible fiberoptic bronchoscope (FOB) is an option for DLT intubation. The difficult process of fiberoptic intubation is that the different properties of polyvinyl chloride and silicone DLTs may affect railroading differently. Therefore, we aimed to compare intubation using polyvinyl chloride and silicone DLTs over an FOB. @*Methods@#Patients aged 19–75 years who required one-lung ventilation under general anesthesia were enrolled in this study. After induction of anesthesia, the anesthesiologist intubated the DLT using FOB. The primary outcome was the difficulty of railroading over the flexible FOB scaled into five grades (I, II-1, II-2, III, and IV). Additionally, the intubation time and mucosal damage were recorded. @*Results@#A total of 46 patients participated in this study, 23 each in the silicone and polyvinyl groups. The difficulty of railroading over the FOB was significantly different between the two groups (P < 0.001). In the silicone group, the grades of difficulty in railroading were limited to I and II-1; 20 patients (87%) presented no difficulty in advancing the tube. In contrast, in the polyvinyl group, 13 patients (57%) had scores of II-2 and III. Both the intubation time and mucosal damage were significantly better in the silicone group than in the polyvinyl group. @*Conclusions@#Intubation using a silicone DLT over an FOB was easier and faster than that with a polyvinyl chloride DLT with lesser trauma around the glottis.

Cochlear Implantation in the Elderly: Speech Performance, Associated Factor, Complication, and Surgical Safety

Background and Objectives@#The guidelines for cochlear implantation (CIs) are expanding, and the number of CI procedures performed on the elderly is increasing. The purpose of this study was to analyze the results and safety of cochlear implantation in the elderly, as well as to evaluate the predictive factors on CI outcomes. @*Subjects and Methods@#The study included 56 patients aged ≥40 years, who received CIs between 2009 and 2020. They were divided into two groups: 27 younger adults (40-64 years) and 29 elderly (>64 years). The study compared their pre- and postoperative speech perception and category of auditory performance (CAP) scores, surgical complications, and hospitalization periods. It also evaluated associated factors in the elderly group by examining categorical and continuous variables and postoperative CAP score. @*Results@#There was a significant improvement in speech recognition tests (both word and sentence) and CAP scores in both groups compared to the pre-implantation scores (p<0.001). Postoperative results were slightly lower in the elderly group than in younger adults for sentence recognition and CAP scores, except for word recognition. No significant associated factors were found on postoperative CAP scores, except for etiology. Postoperative CAP significantly improved in the sudden hearing loss group compared to the groups with other etiologies (p=0.045). The elderly group had more comorbidities than that in the younger adult group (p=0.026), but there were no significant differences in postoperative complications and hospitalization periods. @*Conclusions@#While speech recognition and CAP scores were relatively lower in the elderly group compared to the younger adults, the elderly group showed significant improvements in audiological results after CI. Moreover, CI was safe and well tolerated in elderly patients.

Treatment Efficacy of Various Maneuvers for Lateral Canal Benign Paroxysmal Positional Vertigo With Apogeotropic Nystagmus: A Randomized Controlled Trial

Objectives@#The aim of this study was to determine the most effective treatment approach by comparing the impacts of various otolith reduction techniques in patients with apogeotropic lateral semicircular canal benign paroxysmal positional vertigo (LC-BPPV). @*Methods@#We performed a multicenter randomized prospective study from January to December 2015, involving 72 consecutive patients with apogeotropic LC-BPPV. The patients were divided into three treatment groups: therapeutic head-shaking (group A), the Gufoni-Appiani maneuver (group B), and the cupulolith repositioning maneuver (CuRM; group C). Each group underwent evaluation and treatment up to the fourth week. Treatment success was defined as the disappearance of positional vertigo and nystagmus. @*Results@#This study included 72 patients (49 male and 23 female), with a mean (±standard deviation) age of 55.4±13.5 years. The mean duration of vertigo experienced prior to treatment was 3.9±4.4 days. The mean latency and duration of nystagmus were 2.7±3.0 seconds and 47.9±15.8 seconds, respectively. The overall treatment frequency was 2.0±0.9. The number of treatments differed significantly among the three groups (P0.05). However, CuRM was the only method with a 100% treatment success rate. @*Conclusion@#While no clear difference was observed among the three treatments for LC-BPPV, CuRM was found to be superior to the other approaches in the long term.

Behavioral problems in Korean children and adolescents with atopic dermatitis

Purpose@#Patients with atopic dermatitis (AD) experience a chronic relentless course which may affect emotional and behavioral problems. Moreover, AD could affect serious psychosocial problems due to its disfiguring skin conditions, particularly in adolescents who are under various stresses. The aim of this study was to investigate behavioral problems in children and adolescents with AD and to identify associated clinical factors. @*Methods@#A total of 69 subjects with AD were enrolled in this study. The severity of AD was assessed using the SCORAD (Scoring of Atopic Dermatitis) index and divided into 2 groups: mild-to-moderate and severe groups. Behavioral problems were assessed by using the Korean Child Behavior Checklist (K-CBCL). @*Results@#The severe AD group had higher total behavior problem scores and internalizing scores than the mild-to-moderate group. Social problem and attention problem scores were slightly higher in the severe AD group than in the mild-to-moderate AD group. The DSM (diagnostic and statistical manual of mental disorders)-anxiety, obsessive compulsive problems, and sluggish cognitive tempo problems were more frequently observed in the severe AD group. Longer disease duration was an independent risk factor of internalizing problems in subjects with AD. @*Conclusion@#This study showed that subjects with severe AD had higher total behavioral problem scores, particularly internalizing scales. Their behavioral problems may have poor compliance and consequently poor outcomes as well. Clinicians should be aware that children and adolescents with severe AD have more behavioral problems and that an interdisciplinary approach with medical and psychological supports is necessary for proper management.

Comparison of Clinical and Radiologic Findings Between Perforated and Non-Perforated Choledochal Cysts in Children

Objective@#To compare the clinical and radiologic findings between perforated and non-perforated choledochal cysts in children. @*Materials and Methods@#Fourteen patients (mean age ± standard deviation, 1.7 ± 1.2 years) with perforated choledochal cysts (perforated group) and 204 patients (3.6 ± 3.8 years) with non-perforated choledochal cysts (non-perforated group) were included between 2000 and 2019. All patients underwent choledochal cyst excision after ultrasound, CT, or MR cholangiopancreatography. Relevant data including demographics, clinical symptoms, laboratory findings, imaging findings, and outcomes were analyzed. Statistical differences were compared using the Mann-Whitney U test and Fisher’s exact test. @*Results@#Choledochal cyst perforation occurred only in children under the age of 4 years. Acute symptoms, including fever (p < 0.001), were more common in the perforated group than in the non-perforated group. High levels of white blood cells (p = 0.004), C-reactive protein (p < 0.001), and serum amylase (p = 0.002), and low levels of albumin (p < 0.001) were significantly associated with the perforated group. All 14 patients with perforated choledochal cysts had ascites, whereas only 16% (33/204) of patients in the non-perforated group had ascites (p < 0.001). In the subgroup of patients who had ascites, a large amount of ascites (p = 0.001), increase in the amount of ascites in a short time (p < 0.001), complex ascites (p < 0.001), and perihepatic pseudocysts (p < 0.001) were more common in the perforated group than in the non-perforated group. @*Conclusion@#Children with perforated choledochal cysts have characteristic clinical and radiologic findings compared to those with non-perforated choledochal cysts. In young children with choledochal cysts, perforation should be differentiated in cases with acute symptoms, laboratory abnormalities, and characteristic ascites findings.

Environmental management education using immersive virtual reality in asthmatic children

Purpose@#Awareness of environmental control is considered a major influence on the performance of asthma self-management behaviors that are involved in maintaining effective control of asthma. The aim of this study was to investigate whether immersive virtual reality (VR) education is effective in environmental control education for asthmatic children. @*Methods@#Thirty asthmatic children aged 9 to 13 years with aeroallergen sensitization were enrolled. Environmental control education for asthmatic subjects were performed using either immersive VR (VR group) or conventional leaflets provided by asthma specialists (control group). Five questionnaires, such as awareness of environmental control, memory, assessment of intent to act, satisfaction test, and asthma control test (ACT) questionnaires were used for estimating the effects of education. @*Results@#Awareness of environmental control, memory, and intent to act scores were significantly increased after education in both groups and the scores were maintained high until 4 weeks after education. In both group, ACT scores were maintained high scores before and 4 weeks after education. Satisfaction scores were very high in the VR group. @*Conclusion@#The increased scores in awareness of environmental control and intent to act indicate that the environmental control education using VR is worthy of attention as an effective educational tool for asthma management. Application of further developed techniques, including active environmental intervention by participants in VR, could be applied to effective asthma management.

Chronic Recurrent Multifocal Osteomyelitis Associated With Inflammatory Bowel Disease Successfully Treated With Infliximab

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory bone disorder presenting with sterile osteomyelitis, most often presenting in childhood. Although the etiology is understood incompletely, its association with other auto-inflammatory diseases including inflammatory bowel disease (IBD); psoriasis; Wegener’s disease; arthritis; and synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome suggests that dysregulated innate immunity may play an important role in the pathogenesis. We report a case of a 13-year-old boy with CRMO associated with Crohn’s disease (CD) successfully treated with infliximab after failure of non-steroidal anti-inflammatory drug (NSAID) treatment. He initially was diagnosed with CRMO based on symmetric and aseptic bone lesions with no fever, lack of response to antibiotic treatment, vertebral involvement, and normal blood cell counts. Despite five months of NSAID treatment, his musculoskeletal symptoms were aggravated, and he developed gastrointestinal symptoms. Finally, he was diagnosed with CRMO associated with CD. Due to the severity of symptoms, infliximab was initiated and produced symptom improvement. This case supports infliximab as another choice for treatment of bowel symptoms in addition to the bone and joint symptoms of CRMO when other first-line treatments are ineffective.

Incidence and Cognitive Decline of Alzheimer’s Disease and Other Dementia by Apolipoprotein ε4 Allele Presence: A Community-Based Cohort Study in Korean Elderly

Objective@#This study aimed to investigate the role of apolipoprotein E (APOE) ε4 allele to the incidence of dementia and cognitive decline in a cohort of a Korean community. @*Methods@#From a community-based dementia-free cohort, 357 participants were genotyped. Participants underwent 2 cognitive assessments separated by a hiatus between 6 to 7 years and were diagnosed as healthy control (n=297), Alzheimer’s disease (AD) (n=44), and other dementia (n=16) at the second assessment. Incidence risk and onset age of disease according to APOE ε4 presence were analyzed in AD and other dementia. Differences in cognitive decline rate depending on APOE ε4 were also examined across all groups. @*Results@#The relative risks and onset age of dementia were not different by the presence of the APOE ε4 allele. Cognitive decline was more prominent in the presence of APOE ε4 allele (score change=7.4) than non-presence (score change=3.1), and this interaction was significant only in the AD group (F=10.51, p=0.003). @*Conclusion@#The APOE ε4 alleles can be a critical factor in predicting cognitive change for AD in the Korean community population but not in predicting AD incidence. This finding suggest that clinicians consider the presence of APOE ε4 allele examining patients with rapid declining dementia.

Impact of Mediastinal Lymphadenopathy on the Severity of COVID-19 Pneumonia: A Nationwide Multicenter Cohort Study

Background@#We analyzed the differences between clinical characteristics and computed tomography (CT) findings in patients with coronavirus disease 2019 (COVID-19) to establish potential relationships with mediastinal lymphadenopathy and clinical outcomes. @*Methods@#We compared the clinical characteristics and CT findings of COVID-19 patients from a nationwide multicenter cohort who were grouped based on the presence or absence of mediastinal lymphadenopathy. Differences between clinical characteristics and CT findings in these groups were analyzed. Univariate and multivariate analyses were performed to determine the impact of mediastinal lymphadenopathy on clinical outcomes. @*Results@#Of the 344 patients included in this study, 53 (15.4%) presented with mediastinal lymphadenopathy. The rate of diffuse alveolar damage pattern pneumonia and the visual CT scores were significantly higher in patients with mediastinal lymphadenopathy than in those without (P < 0.05). A positive correlation between the number of enlarged mediastinal lymph nodes and visual CT scores was noted in patients with mediastinal lymphadenopathy (Spearman’s ρ = 0.334, P < 0.001). Multivariate analysis showed that mediastinal lymphadenopathy was independently associated with a higher risk of intensive care unit (ICU) admission (odds ratio, 95% confidence interval; 3.25, 1.06-9.95) but was not significantly associated with an increased risk of in-hospital death in patients with COVID-19. @*Conclusion@#COVID-19 patients with mediastinal lymphadenopathy had a larger extent of pneumonia than those without. Multivariate analysis adjusted for clinical characteristics and CT findings revealed that the presence of mediastinal lymphadenopathy was significantly associated with ICU admission.

Immunogenicity of an inactivated rabies vaccine for animals derived from the recombinant ERAGS strain

Purpose@#The aims of the present study were to evaluate the immunogenicity of an inactivated rabies vaccine based on the ERAGS strain @*Materials and Methods@#The ERAGS virus propagated in Vero cells was inactivated with 3 mM binary ethylenimine for 8 hours. Three types of inactivated rabies vaccines were prepared to determine the minimum vaccine virus titers. Four further types of inactivated rabies vaccines were prepared by blending inactivated ERAGS with four different adjuvants; each vaccine was injected into mice, guinea pigs, and dogs to identify the optimal adjuvant. The immunogenicity of a Montanide (IMS) gel-adjuvanted vaccine was evaluated in cats, dogs, and cattle. Humoral immune responses were measured via a fluorescent antibody virus neutralization method and a blocking enzyme-linked immunosorbent assay. @*Results@#The minimum virus titer of the inactivated rabies vaccine was over 107.0 50% tissue culture infectious doses (TCID50 values)/mL. Of the four kinds of adjuvants, the IMS gel-adjuvanted vaccine induced the highest mean viral neutralizing antibody (VNA) titers of 6.24 and 2.36 IU/mL in guinea pigs and dogs, respectively, and was thus selected as the vaccine for the target animals. Cats, dogs, and cattle inoculated with the IMS gel-adjuvanted vaccine developed protective VNA titers ranging from 3.5 to 1.2 IU/mL at 4 weeks post-inoculation (WPI). @*Conclusion@#Our data indicate that cats, dogs, and cattle inoculated with an inactivated rabies vaccine derived from the ERAGS strain developed protective immune responses that were maintained to 12 WPI.

Erratum to "Modulation of Human Cardiac Progenitors via Hypoxia-ERK Circuit Improves their Functional Bioactivities" Biomol. Ther. 21 (2013) 196-203

no abstract available

A Case with Multiple Fungal Coinfections in a Patient who Presented with Pancoast Syndrome

Invasive fungal infection (IFI) is a serious threat to pediatric patients with cancer given high morbidity and mortality. We present an 18-year-old male with precursor T-cell lymphoblastic leukemia who developed Pancoast syndrome, presented with paresthesia and numbness in the right shoulder and arm during a neutropenic fever period. He was diagnosed with pneumonia in the right upper lung field. He was later found to have an invasive pulmonary fungal infection caused by multiple fungi species, including Rhizomucor, confirmed by histology and polymerase chain reaction (PCR) (proven infection), Penicillium decumbens diagnosed by PCR, and Aspergillus suspected from galactomannan assay (probable infection). Unfortunately, the patient's condition further worsened owing to the aggravation of leukemia, chemotherapy-induced neutropenia, and bacterial coinfection, leading to multiorgan failure and death. Here, we report a case of IFI caused by multiple fungal species that presented as Pancoast syndrome.

Isolation and identification of mammalian orthoreovirus type 3 from a Korean roe deer (Capreolus pygargus)

Mammalian reovirus (MRV) causes respiratory and intestinal disease in mammals. Although MRV isolates have been reported to circulate in several animals, there are no reports on Korean MRV isolates from wildlife. We investigated the biological and molecular characteristics of Korean MRV isolates based on the nucleotide sequence of the segment 1 gene. In total, 144 swabs from wild animals were prepared for virus isolation. Based on virus isolation with specific cytopathic effects, indirect fluorescence assays, electron microscopy, and reverse transcription-polymerase chain reaction, one isolate was confirmed to be MRV. The isolate exhibited a hemagglutination activity level of 16 units with pig erythrocytes and had a maximum viral titer of 105.7 50% tissue culture infectious dose (TCID50)/mL in Vero cells at 5 days after inoculation. The nucleotide and amino-acid sequences of the partial segment S1 of the MReo2045 isolate were determined and compared with those of other MRV strains. The MReo2045 isolate had nucleotide sequences similar to MRV-3 and was most similar (96.1%) to the T3/Bat/Germany/342/08 strain, which was isolated in Germany in 2008. The MReo2045 isolate will be useful as an antigen for sero-epidemiological studies and developing diagnostic tools.

Expression of the VP2 protein of feline panleukopenia virus in insect cells and use thereof in a hemagglutination inhibition assay

Feline panleukopenia virus (FPV) causes leukopenia and severe hemorrhagic diarrhea, killing 50% of naturally infected cats. Although intact FPV can serve as an antigen in the hemagglutination inhibition (HI) test, accidental laboratory-mediated infection a concern. A non-infectious diagnostic reagent is required for the HI test. Here, we expressed the viral protein 2 (VP2) gene of the FPV strain currently prevalent in South Korea in a baculovirus expression system; VP2 protein was identified by an indirect immunofluorescence assay, electron microscopy (EM), Western blotting (WB), and a hemagglutination assay (HA). EM showed that the recombinant VP2 protein self-assembled to form virus-like particles. WB revealed that the recombinant VP2 was 65 kDa in size. The HA activity of the recombinant VP2 protein was very high at 1:215. A total of 143 cat serum samples were tested using FPV (HI-FPV test) and the recombinant VP2 protein (HI-VP2 test) as HI antigens. The sensitivity, specificity, and accuracy of the HI-VP2 test were 99.3%, 88.9%, and 99.3%, respectively, compared to the HI-FPV test. The HI-VP2 and HI-FPV results correlated significantly (r = 0.978). Thus, recombinant VP2 can substitute for intact FPV as the serological diagnostic reagent of the HI test for FPV.