• Korean Journal of Veterinary Service
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• v.40 no.3
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• pp.187-192
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• 2017

In this report, fifteen monoclonal antibodies (MAbs) against an avian influenza virus (H9N2 subtype) were newly produced and characterized. These MAbs proved to react to the epitopes of nucleocapsid protein (NP), hemagglutinin (HA), neuraminidase (NA) and non-structural protein 1 (NS1) of Korean H9N2 strain, respectively. Two HA-specific MAbs showed the ability to inhibit the hemagglutination activity of H9N2 subtype avian influenza virus when tested by hemagglutination inhibition (HI) assay. All MAbs did not cross-react with other avian-origin viruses (Newcastle disease virus, infectious bursal disease virus, infectious bronchitis virus and avian rotavirus) by immunofluorescence test or enzyme-linked immunosorbent assay. The MAbs produced in this study could be useful as the materials for diagnostics and therapeutics against Korean-lineage H9N2 virus infections.

• Parasites, Hosts and Diseases
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• v.36 no.3
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• pp.203-206
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• 1998

Two-day-old commercial chicks were inoculated orally with 2 × 106 oocysts of Cwptosporinium bailevi and vaccinated with 103.5 EID50/head of a commercially available avian infectious bronchitis (IB) live virus vaccine at 4 and 14 days following inoculation. Chicks infected with C. baileyi were shown to have an immunosuppressive effect on IB virus. It is concluded that infection with the protozoon in early life may increase their susceptibility to IB.

• Korean Journal of Poultry Science
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• v.46 no.4
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• pp.263-269
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• 2019

Infectious bronchitis virus (IBV) is an acute respiratory disease, causing economic losses in poultry production. IBV commonly manifests respiratory disease symptoms and poor egg quality in poultry, affecting overall performance of both broilers and layers. IBV infection further predisposes poultry to secondary opportunistic bacterial infections. IBV undergoes rapid genetic evolution resulting in various new strains. There is no cross protection among IBV serotypes which makes full protection against wild-type IBV virtually impossible. In this study, recently isolated IBVs (K24/18, K29/18, K183/18) from Korean broiler farms were genetically analyzed based on S1 gene. According to the results, IBV isolates showed highest homology with QX-IBV. However, phylogenetic tree analysis revealed that isolates were divided into distinct sub-clusters within QX-IBV. To determine pathogenicity of IBV, day-old chicks were challenged with IBV through ocular route. After challenging the chicks, we executed microscopic examination, virus detection in their organs, and observation of clinical signs and mortality. We found that the K24/18, K29/18, K183/18 challenge groups showed 28%, 57%, and 42% mortality, respectively, with high microscopic trachea lesion scores, indicating that these QX-IBV-like strains are pathogenic to chicks and can therefore be a threat to poultry production.

• Korean Journal of Veterinary Research
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• v.29 no.4
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• pp.503-515
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• 1989

Critical parameters affecting sensitivity and specificity of an enzyme-linked immunosorbent assay(ELISA) for detection of antibodies to avian infections bronchitis virus(IBV) were standardized. By adopting the optimized conditions an equation calculating ELISA antibody titers from the observations at single serum dilution was formulated. The purified antigen of IBV Mass-41 strain was dispensed into polystyrene microplate wells at a concentration of 300ng per well($100{\mu}l$) and the plates were coated by completey drying at $37^{\circ}C$. Diluted chicken serum and horseradish peroxidase conjugated goat anti-chicken IgG were added in order in $100{\mu}l$ volumes per well and allowed to react for 30 minutes each at room temperature. Just before use and after each reaction the plates were washed three times with distilled water. Finally o-phenylenediamine solution was added as an enzyme substrate. After incubation for another 15 minutes at room temperature absorbances were read at 492nm. Hyperimmune serum against Mass-41 strain was used as internal reference positive(IRP) serum. After repeated titration of IRP and negative serum, a constant titer of IRP was determined. Serum titrations were carried out for various sample sera together with IRP and negative sera and the observed titers of sample sera were corrected by reflecting the ratio between observed and constant titers of IRP serum. These corrected titers of the sample sera were plotted against sample/positive(S/P) OD ratios. All the OD's measured in the serum titrations were also corrected by substracting negative serum OD. The following equation was formulated from the above data; $Log_{10}$ ELISA titer=$5.568({\log}_{10}S/P)+4.161$ Thus it was possible to calculate ELISA titer by measuring absorbance at 1/400 single serum dilution. Titer measured by cross ELISA tests employing Mass-41 strain and three local IBV isolates were similar. These results suggest that the ELISA tests standardized in this study can be used for evaluating not only vaccinal immunity but also for infection status against fields IBV's.

• Korean Journal of Veterinary Service
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• v.31 no.1
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• pp.43-55
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• 2008

Recently, the major viral diseases, Newcastle disease (ND), infectious bronchitis (IB), low pathogenic avian influenza (LPAI), avian pneumovirus infection (APV), Marek's disease (MD) and infectious bursal disease (IBD), have led to huge economic losses in chicken industry of Korea. To evaluate prevalence of the major viral disease infections in broiler breeder and broiler farms, epidemiological survey has been conducted in Jeonbuk province from 2005 to 2007 by serological ELISA test for APV, PCR for MD, and RT-PCR for ND, IB, LPAI and IBD, respectively. A total of 424 cases was submitted to our laboratory for diagnosis of the major viral disease from broiler breeder and broiler farms in the above period. The diagnosed results were analysed for the detection rate of infections on basis of years, seasons and ages, respectively. This study was showed that the detection rates of ND and APV were considerably high for every years regardless of seasons and ages in both broiler breeder and commercial broiler. In comparison with detection rates of ND and APV, IB and LPAI were lower but detected around 10% for every years. Especially, detection rate of IB was significantly high in commercial broiler than in broiler breeder. Therefore, to minimize economic losses for broiler breeder and broiler farms, it will need for effective countermeasures to decrease detection rate of the viral respiratory diseases. Although the detection rates of MD and IBD were gradually decreased from 2005 to 2007 in both broiler breeder and commercial broiler, it will continually make an effort about disease control for increasing productivity in chicken industry.

• Korean Journal of Veterinary Research
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• v.63 no.4
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• pp.41.1-41.6
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• 2023

Many viruses can infect different types of birds, with poultry being the most susceptible. These viral diseases have a direct negative impact on the poultry industry, with significant economic losses. This study examined a group of the most important viruses that infect backyard chickens in 2 specific areas of Basrah Governorate, south of Iraq. The study analyzed avian influenza viruses (AIVs), Newcastle disease virus (NDV), and infectious bronchitis virus (IBV). Two hundred and ninety oropharyngeal swabs, 150 from Abu Al-Khasib and 140 from Shatt Al-Arab regions in the Basrah governorate, were obtained from backyard chickens with clear respiratory signs. The samples were subjected to viral RNA extraction, and the viral nucleic acids were detected using a reverse transcriptase polymerase chain reaction technique. The overall rate of viral infections was 74.8%, which varied depending on the type of virus: 15.8%, 31.3%, and 27.5% for AIV, NDV, and IBV, respectively. The NDV and IBV had much higher infection rates than that of AIV. In addition, the prevalence of AIV in the Shatt Al Arab district was significantly higher than in the Abul Khasib district. Moreover, there were no significant differences between the NDV and the IBV distributions in either of the targeted regions in this study.

• Korean Journal of Poultry Science
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• v.16 no.3
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• pp.175-192
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• 1989

A total of 9, 012 cases was submitted for diagnosis of chicken diseases to Veterinary Research Institute, Rural Development Administration from domestic chicken farms during 18 years from 1971 to 1988. Of them, 6, 181 cases diagnosed as the infectious disease were investigated for the detection rate of infections on basis of you, season , and chicken age. The results obtained were summarized as followings：1. Detection rate or the infections was lowest as 49.3% in the year 1973, and highest as 78.6% in 1985 (average 68.6%). 2. Of infections detected, bacterial diseases were most frequent (32.6%), and followed in order by viral (26.3%), parasitic (7.7%), and fungal diseases (2.1%) in geneal. 3. The most frequently detected bacterial diseases in order of prevalence were mycoplasmosis (8.8%), colibacillosis (8.5%), and staphylococcosis (5.8%), and followed by salmonellosis pullorum disease , yolk sac disease, and salpingitis (0.8-1.5%). 4. In viral diseases, 7.5% of infections detected was lymphoid leukosis and 7.2%-Marek's disease, 4.4%-Newcastle disease, 2.0%-infectious laryngotracheitis, 1.7%-infectious bursal disease, and 1.0%-avian encephalomyelitis, while detection rate of infectious bronchitis, egg drop syndrome '76, and inclusion body hepatitis was less than 1.0%, respectively. 5. The most prevalent parasitic disease was coccidiosis (4.5%), followed by ascariasis (1.4%). The detection rate of other parasitic diseases including leucocytozoonosis, black head , heterakiasis, and ectoparasitosis was very as 0.2-0.7%, respectively： In fungal diseases, 2.0% of infections was detected as aspergillosis, and followed by candidiasis (0.1%). 6. Detection rate of the infections on basis of season was somewhat higher in summer. (27.7%), and autumn (27.7%) than in winter (23.5%), and spring (21.5%) in general. In bacterial, viral, and fungal diseases, there were the similar tendencies of detection rate as in infections, while parasitic diseases were much highly detected in summer (34.3%), and autumn (39.5%) than in any other season. 7. Among bacterial diseases colibacillosis was most frequently detected in summer, and staphylococcosis in autumn. In detection rate of viral diseases, Marek's disease, infectious laryngotracheitis, and infectious bursal disease was highest in summer, lymphold leukosis, fowl pox and egg drop syndrome '76 in autumn, and infectious trachitis in winter, repectively. The majority of important parasitic diseases including coccidiosis were highly detected in summer and autumn. 8. On basis of chicken age, detection rate of infections were highest in chicken of growing period between 30 and 150 days of age (41.4%), and followed by 35.3% in laying chicken over 150 days of age, and 17.3% in chicken of brooding age under 30 days of age. Bacterial, and parasitic diseases were most frequently detected in chicken of growing period, viral diseases in chicken of growing, and laying period as nearly equal rate of detection, and fungal diseases in chicken of brooding age.