• Korean Journal of Veterinary Service
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• v.19 no.1
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• pp.1-29
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• 1996

This study was conducted to elucidate the pathogenesis of Aujeszky's disease virus(ADV) by histopathologic examination. The first Korean ADV Isolate, which was isolated from piglets with clinical signs of Aujeszky's disease in Yangsan(YS) county, Kyungnam province, was inoculated into 32 days old piglets with a dose of $10^{5.9}$$TCID_{50}/ml$ through intranasal or intramuscular route. These piglets were sacrificed at intervals of every 24hrs for 8 days. The virulence of YS strain was determined by the observation of clinical signs, gross findings, and histopathologic changes in tissues. The virus recovery test was performed from brain, spleen, lung and tonsil in cell culture. The pathogenesis of YS strain was determined by the observation of histopathologlc lesions in CNS and neuronal tracts. The major clinical signs were fever, anorexia, dyspnea, constipation, tremor, ataxia, circling movement, hindleg paralysis and salivation. The clinical signs were more severe in piglets of the group inoculated intranasally than those of the intramuscularly inoculated gorup. Lymphocytopenia was detected on day 5 to day 6 postinoculation (PI). The ADV was recovered from the tissue homogenates of tonsil, lung, spleen and cerebrum in cell culture. The highest virus titer was detected from tonsil between day 6 and day 7 PI. Reddish sublobar consolidation foci were scattered in the apical and cardiac lobes of lung. Although yellowish necrotic foci were detected in tonsil and liver, hemorrhagic lesions were mainly observed in heart, kidney and lymph nodes. Histopathologically, degeneration and necrosis of nerve cells, nonsuppurative meningoe-ncephalitis, nodular gliosis and perivascular cuffings were observed in CNS. Multifocal fibronecrotic foci were observed in lung, liver, lymph nodes and spleen. The major pathologic changes were detected in the midbrain, pons and medulla oblongata. Eosinophilic intranuclear inclusion bodies were mainly observed in epithelia and /or macrophages of tonsil, liver, lung, spleen and submandibular lymph nodes, and neurons of brain, respectively. Observation of viral particles at various stages of replication were possible from the endothelial cells of the alveolar capillaries and tonsillar crypt epithelia by transmission electron microscope.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.280-286
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• 2007

We evaluated a commercial biopreparation of plant growth-promoting rhizobacteria (PGPR) strains Bacillus subtilis GB03 and B. amyloliquefaciens IN937a formulated with the carrier chitosan (Bio Yield) for its capacity to elicit growth promotion and induced systemic resistance against infection by Cucumber Mosaic Virus (CMV) and Pseudomonas syringae pv. tomato DC3000 in Arabidopsis thaliana. The biopreparation promoted plant growth of Arabidopsis hormonal mutants, which included auxin, gibberellic acid, ethylene, jasmonate, salicylic acid, and brassinosteroid insensitive lines as well as each wild-type. The biopreparation protected plants against CMV based on disease severity in wild-type plants. However, virus titre was not lower in control plants and those treated with biopreparation, suggesting that the biopreparation induced tolerance rather than resistance against CMV. Interestingly, the biopreparation induced resistance against CMV in NahG plants, as evidenced by both reduced disease severity and virus titer. The biopreparation also elicited induced resistance against P. syringae pv. tomato in the wild-type but not in NahG transgenic plants, which degrade endogenous salicylic acid, indicating the involvement of salicylic acid signaling. Our results indicate that some PGPR strains can elicit plant growth promotion by mechanisms that are different from known hormonal signaling pathways. In addition, the mechanism for elicitation of induced resistance by PGPR may be pathogen-dependent. Collectively, the two-Bacilli strain mixture can be utilized as a biological inoculant for both protection of plant against bacterial and viral pathogens and enhancement of plant growth.

• Korean Journal of Veterinary Service
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• v.46 no.3
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• pp.193-202
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• 2023

Porcine epidemic diarrhea is an infectious intestinal disease caused by the porcine epidemic diarrhea virus (PEDV). Especially, when suckling piglets are infected, the mortality rate is close to 100%. PEDV is classified into G1 and G2 types based on genetic differences. The G2 type PEDV outbreak in the United States in 2013 was highly pathogenic and contagious, and it has spread worldwide and caused continuous economic losses. Most commercial vaccines used are G1 type vaccines, and existing vaccines do not fully protect piglets due to genetic differences. In this study, we evaluated the safety of the newly developed G2 type attenuated HSGP vaccine strain by inoculating it into piglets and testing whether the vaccine virus spreads to the non-vaccinated, negative pigs and whether the vaccine reverts to its virulence during serial passage experiments. Each experiment lasted for 7 days for each passage, and fecal viral titers, clinical symptoms, and weight gain were measured daily. After the experiment, necropsy was performed to measure intestinal virus titer and pathological evaluation. As a result of the first passage, no transmission of the vaccine virus to negative pigs co-housed with vaccinated pigs was observed. In addition, after four consecutive passage experiments, the clinical symptoms and small intestine lesions were gradually alleviated, and no virus was detected in the feces in the fourth passage experiment. Therefore, it was concluded that the vaccine was safe without virulence reversion in accordance with the guidelines of the current licensing authority. However, further studies are needed on the genetic changes and biological characteristics of the mutant virus that occur during successive passages of the attenuated vaccine since the replication and clinical symptoms of the virus increased until the third passage during successive passages of the vaccine virus. Based on this study, it was concluded that virulence reversion and safety evaluation of attenuated vaccines through serial passage in target animals can be useful to evaluate the safety of attenuated viruses.

• Korean Journal of Veterinary Service
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• v.46 no.4
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• pp.263-268
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• 2023

Despite regular vaccinations, equine influenza virus (EIV) and Streptococcus equi subsp. equi (strangles) are the cause of highly contagious respiratory infections in horses. Many recent studies have reported that the concurrent administration of two vaccines could simplify horse management and minimize veterinary expenses. However, there is little information available regarding the efficacy of concurrent vaccinations against EIV and strangles. In this study, we evaluated EIV-specific antibody responses following the single EIV vaccination with the recombinant viral-vectored EIV vaccine or concurrent vaccination with the EIV and inactivated strangles vaccines. Blood samples were collected at 1-, 2-, 4-, and 8 weeks post-immunization (wpi) from each group. EIV-specific antibodies were evaluated by enzyme-linked immunosorbent assay (ELISA) and hemagglutination inhibition (HAI) assay. Both single and concurrent vaccination showed similar levels of EIV-specific serum immunoglobulin g (IgG) at 1 and 2 wpi. However, at 4 to 8 wpi, the EIV-only vaccination group showed significantly higher serum IgG levels than those from the concurrently vaccinated group. The HAI titers showed similar trends as the ELISA data, except at 8 wpi when both groups presented HAI titers with no significant differences. These data demonstrate that the concurrent vaccination against EIV and strangles could compromise the humoral immune response to equine influenza between vaccination intervals, which suggests the use of the consecutive vaccination protocol for EIV and strangles rather than concurrent vaccination.

• Journal of Veterinary Science
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• v.24 no.5
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• pp.55.1-55.12
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• 2023

Background: Peste des petits ruminants (PPR), caused by the PPR virus (PPRV), is an acute and fatal contagious disease that mainly infects goats, sheep, and other artiodactyls. Peripheral blood mononuclear cells (PBMCs) are considered the primary innate immune cells. Objectives: PBMCs derived from goats were infected with PPRV and analyzed to detect the relationship between PPRV replication and apoptosis or the inflammatory response. Methods: Quantitative real-time polymerase chain reaction was used to identify PPRV replication and cytokines expression. Flow cytometry was conducted to detect apoptosis and the differentiation of CD4⁺ and CD8⁺ T cells after PPRV infection. Results: PPRV stimulated the differentiation of CD4⁺ and CD8⁺ T cells. In addition, PPRV induced apoptosis in goat PBMCs. Furthermore, apoptosis and the inflammatory response induced by PPRV could be suppressed by Z-VAD-FMK and Z-YVAD-FMK, respectively. Moreover, the virus titer of PPRV was attenuated by inhibiting caspase-1-dependent apoptosis and inflammation. Conclusions: This study showed that apoptosis and the inflammatory response play an essential role in PPR viral replication in vitro, providing a new mechanism related to the cell host response.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.73-83
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• 2023

Purpose: This study aimed to investigate the viral load dynamics in children with underlying malignancies diagnosed with symptomatic coronavirus disease 2019 (COVID-19). Methods: This was a retrospective longitudinal cohort study of patients <19 years old with underlying hemato-oncologic malignancies that were diagnosed with their first symptomatic severe acute respiratory syndrome coronavirus 2 polymerase chain reaction (PCR)-confirmed COVID-19 infection during March 1 to August 30, 2022. Review of electronic medical records and telephone surveys were undertaken to assess the clinical presentations and transmission route of the patients. Thresholds of negligible likelihood of infectious virus was defined as E gene reverse transcription (RT)-PCR cycle threshold (Ct) value ≥25. Results: During the 6-month study period, a total of 43 children with 44 episodes of COVID-19 were included. Of the 44 episodes, the median age of the patients included was 8 years old (interquartile range [IQR], 4.9-10.5), and the most common underlying disease was acute lymphoid leukemia (n=30, 68.2%), followed by patients post-hematopoietic stem cell transplantation (n=8, 18.2%). Majority of the patients had mild COVID-19 (n=32, 72.7%), and three patients (7.0%) had severe/critical COVID-19. Furthermore, 2.3% (n=1) died of COVID-19 associated acute respiratory distress syndrome. The largest percentage of the patients showed E gene RT-PCR Ct value ≥25 between 15-21 days (n=13, 39.4%), followed by 22-28 days (n=10, 30.3%). In 15.2% (n=5), E gene RT-PCR Ct value remained <25 beyond 28 days after initial positive PCR. Refractory malignancy status (β, 67.0; 95% confidence interval, 7.0-17.0; P=0.030) was significantly associated with prolonged duration of E gene RT-PCR <25. A patient with prolonged duration of E gene RT-PCR Ct value <25 was suspected to have infectivity shown by the transmission of the virus to his mother at day 86 after his initial positive test. Conclusions: Children that acquire symptomatic COVID-19 during refractory malignancy state are at a high risk for prolonged shedding warranting PCR-based transmission precautions in this cohort of patients.

• Korean Journal of Poultry Science
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• v.35 no.1
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• pp.85-99
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• 2008

Avian reovirus (ARV) is a causative agent of viral arthritis/tenosynovitis, and malabsorption syndrome in broiler. The characteristics of malabsorption syndrome caused by ARV are diarrhea, poor feed conversion and stunting. Therefore, ARV infection has been recognized as one of the most important disease in the poultry industry because of economical losses. However, few study of ARV infection in broiler industry has been conducted in Korea. To evaluate the presence of ARV infection in broiler farms, epidemiological survey such as serological test and virus isolation has been conducted. For the serological survey using ELISA method, we selected five broiler farms which were located at different area and had a history of growth retardation, lameness, diarrhea and poor feathering. From these farms serum samples were collected at 1 day, 14 days and market age. All these farms had no history of vaccination against ARV. In addition to serological survey, we tried to isolate ARV from birds of designated farms at market age and collected feces and tissue samples such as cecal tonsil, intestine and liver. We were identified ARV by RT-PCR and transmissible electron microscopy. The samples were inoculated into 9-day-old embryonated eggs via the chorioallantoic membrane to observe the pock formation. For the pathogenicity test of ARV isolates, we inoculated with the isolates to the right footpad of 3-week-old SPF chicks and observed clinical signs and pathological changes for 14 days after challenge. Most broilers sampled for serological survey have maternal antibodies which were widely distributed at 1 day and decreased by 14 days. However, at the market age several broiler farms showed fairly high antibody titer against ARV. This increase of antibody titer at market age means the possible infection of ARV during the grow-out period. Among total 15 samples for the isolation of ARV. 2 samples were positive by RT-PCR and finally identified as a ARV. We inoculated these isolates in the SPF birds and observed that the antibody titer was increased from 7 days after challenge. However, we did not find any clinical signs both control and challenge groups. Based on the above results, it is clear that the ARV infection has been circulated in the broiler industry and caused significant economic losses. Further study is needed to evaluate the virulence of the isolates in the digestive system of broiler and the molecular characteristics of isolates.

• Korean Journal of Poultry Science
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• v.37 no.4
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• pp.361-372
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• 2010

Serological evaluation for the poultry is important for various reasons, such as designing and assessing the vaccination program and diagnosing diseases and for this reason, serologic tests for the layer flocks have been conducted on a regular basis. Moreover, the nationwide serological survey and analysis are essential to understand the epidemiological status of national poultry industry. In this sense, the study was conducted to evaluate the immune status of the layer flocks with the sera submitted to Avian Disease Laboratory, Chungbuk National University in 2009, and several important viral diseases were selected for evaluation including low pathogenic avian influenza (LPAI), Newcastle disease (ND), infectious bronchitis (IB) and avian metapneumovirus (aMPV). For LPAI and ND, the age-related patterns of geometric mean titer (GMT) changes were similar but there were differences in the flock positive rate and the level of GMT due to the different vaccination policy. In the case of IB, the values of GMT showed that the field infection was more prevalent than expected. For aMPV, positive birds in a flock increased as the layers got older, which reflected the course of field infection because vaccination against aMPV was not allowed in 2009. From this study, the immune status for the main viral diseases in layers became more clarified but this information was limited because of only one year study. Therefore, serological survey needs to be conducted on a yearly basis and furthermore include broilers and breeders for a better understanding of the health status in the national poultry industry.

• Korean Journal of Veterinary Service
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• v.24 no.3
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• pp.223-241
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• 2001

From September 1996 to September 1999, 419 Korean-native calves with diseases under 6-month old collected from Kyonggi, Chungcheong, Chonlla and Kyongsang were examined by clinical, microbiological, parasitic, hematologic and histopathological mean. Among them, 124 cases were tested about the neutralization antibodies against infectious bovine rhinotracheitis virus(IBRV), Parainfluenza-3 virus(PI-3V), bovine uiral diarrhea virus(BVDV), bovine ephemeral fever virus(BEFV). In calf diseases in the survey, enteric diseases(72.8%) were most frequently involved and the following orders were taken by respiratory(17.4%) and reproductive (5.0%) disorders. In the causative pathogens associated with calf diseases and motality, 48.4% was induced by bacteria origin and also 35.6% by viral agents. Calf mortality was up to 76.3% in the cae of bacterial diseases and 55.7% in viral diseases. In bacterial diseases, frequent disorders were composed of colibacillosis(52.7%), salmonellosis(13.8%), pasteurellosis(12.8%) and campylobacteriosis(3.9%) and their mortalities showed 73.8% in colibacillosis, 73.0% in pasteurellosis, 67.9% in salmonellosis and 50.0% in campylobacteriosis (50.0%). Among the outbreaks of viral diseases, there were BVD(22.8%), bovine rotavirus infection(20.8%), bovine coronavirus infection(16.8%), bovine respiratory syncytial virus infection(15.4%), IBR(15.4%). Akabane disease(4.7%) and Chuzan diseases(3.4%). Interesting results through this studies were obtained the first isolate to Chuzan virus and Ainovirus in Korea which could be promised the development for diagnostic method and vaccines soon. Calf mortality to Akabane and Chuzan diseases was 100%. Main parasitic diseases were occupied by coccidiosis and babesiosis and their mortality of babesiosis was 20.0%. Other diseases were abomasal impaction(6.7%) and toxicosis(4.5%). The mortality of abomasal impaction was 89.3%. In some causes with malformations(1.9%) were confirmed as anasarca, derodidymus, polymelia, humerus hypoplasia, and tracheal collapse. Calf diseases had mostly been occurred in one month old grout (52.5%) and its prevalence was 25.1% in two to three month old group and 22.4% in four to six month old group. In calf mortality by age, there were 37.9% in one month old group, 18.1% in two and three month old group, and 13.8% in four to six month old group, respectively. The older the age of calf, the less the prevalence of calf enteric diseases. Respiratory diseases in calves to be tested frequently occurred in one to two month old group (41.4%). In one month old calves, the prevalence of enteric disease was 80.0%(p<0.05) and that of reproductive and respiratory disease was 9.5% and 8.2%, respectively. In two month old and four to six month old, enteric disease was 65.7% and 63.8% and respiratory disease was 28.6% and 26.6%. Seasonal prevalence and mortality of Korean-native calf diseases were not a significant difference. Prevalence of calf diseases in summer(31.5%) frequently occurred to compare that in winter(20.3%). Abortion and malformation in calves frequently occurred in spring. Hematological values in 84 calves with clinical signs showed mild to marked leukocytosis. Also, there was slight increase in hematocrit, platelet, mean corpuscular volume and mean plasma volume, but all of those were included the higher level to normal ranges. Calves with respiratory signs showed slightly erythrocytosis. One hundred seventy three calves without clinical signs were not significant different to ill cases in hematological values, but number of platelets was in higher normal range. In 125 calves, 84.8% was taken the antibody to IBRV, but 72% with the antibody had recorded the titer level lower than log$_2$5. The neutralizing antibody levels of higher than $log_{2}5$ to PI-3V and BVD virus were 60.8% and 67.2% cases, respectively. There were the cases of 57.6% had the neutralizing antibody level lower than log$_2$5 to BEFV.

• IMMUNE NETWORK
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• v.1 no.1
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• pp.45-52
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• 2001

Background: Many types of cancer become resistant to current chemotherapeutic and radiotherapeutic intervention. To overcome this situation application of gene therapy by the introduction of suicide genes followed by their prodrugs may be promising. A viral enzyme, Herpes simplex thymidine kinase (HSV-tk), which converts ganciclovir from an inactive prodrug to a cytotoxic agent by phosphorylation, are being actively investigated for use in gene therapy for cancer. The purpose of this study was to determine whether combining prodrug-activating gene therapy and irradiation might result in enhanced antitumor effects. Methods: The HSV-tk gene was cloned into the retroviral vector, pLXSN and established the clones producing retroviruses carrying the HSV-tk gene. The carcinoma cell line, HCT116 and Huh-7 were transduced with high-titer recombinant retroviruses. These cell lines were treated with ganciclovir before or after irradiation for the defining combinational effect of suicide gene therapy and radiotherapy. Results: The titers of cloned PA3 17 amphotropic retroviruses ranged from 4 to 6 X $10^6CFU/ml4$. After selectional periods, the expression of HSV-tk was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR). The growth of cells expressing HSV-tk was inhibited as increase of GCV dose after 48 hr and the growth inhibitory effect of GCV was much higher after 72 hr. When the cells transduced with HSV-tk gene were exposed to radiation, the growth inhibitory effect of GCV was significantly increased, as compared with non-transduced parental cells. Conclusions: The results suggest that the addition of HSV-tk gene therapy to standard radiation therapy may improve the effectiveness of treatment for solid tumors.