• KOREAN POULTRY JOURNAL
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• v.5 no.1 s.39
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• pp.75-75
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• 1973

• Journal of the korean veterinary medical association
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• v.22 no.6
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• pp.337-346
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• 1986

• KOREAN POULTRY JOURNAL
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• s.110
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• pp.100-104
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• 1978

• KOREAN POULTRY JOURNAL
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• v.51 no.10
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• pp.149-151
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• 2019

• Korean Journal of Veterinary Research
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• v.59 no.3
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• pp.123-132
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• 2019

Two infectious bronchitis virus (IBV) K046-12 and K047-12 strains were isolated and the nearly complete genomes of them were sequenced. Sequence comparisons showed that the K046-12 genome was most similar to Korean IBV strains, and the K047-12 genome was most similar to QX-like IBV strains. Phylogenetic analysis showed that nearly all K046-12 and most K046-12 genes were placed in the same cluster as Korean IBV isolates, but the S1 region was placed in the same cluster as Mass-type IBVs. For K047-12, nearly all K047-12 and most K047-12 genes were located in the same cluster as QX-like IBVs, but the M region was located in the same cluster as Korean IBV isolates with K047-12. Recombination analysis confirmed that K046-12 is a recombinant strain with the primary parental sequence derived from Korean IBVs and minor parental sequence derived from Mass-type IBV, and K047-12 is a recombinant strain with the major parental sequence derived from QX-IBV and minor parental sequence derived from Korean IBVs. This study showed that new IBV recombinants are constantly generated among various IBVs, including those used for vaccination. Therefore, genetic analysis of new virus isolates should be performed for effective infectious bronchitis control and appropriate vaccine development.

• Korean Journal of Veterinary Research
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• v.5 no.1
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• pp.43-57
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• 1965

It has been-reported that rabbit serum exhibit an inhibitory action on avian infectious bronchitis virus in embryonating chicken embryo. In this thesis, the biological, serological, physical and chemical properties of normal rabbit serum on the effect of the virus propagation were studied. Throughout the studies, the following experimental results 'were obtained and summarized here. 1. An inhibitory action of rabbit serum on avian infectious bronchitis vrius is due to the normal serum constituents. 2. The nature of the neutralization between normal rabbit serum and the virus is similar to that of the specific antiserum and the virus. 3. Rabbit serum, heat inactivated at $56^{\circ}C$, for 30 minutes, showed its average $log_{10}El,D_{50}Nl$ of 3.7. 4. The inhibitory compound present in the normal rabbit serum is inactivated by means of 5 per cent trypsin, 0.01 M potassium periodate, and absorbed to zymosan. 5. The inhibitory compound was not affected by 0.05 M trichloroacetic acid and 0.005M $KH_2PO_4$. 6. The higher the temperature of heat inactivation of rabbit serum caused the lesser the neutralizing effect on the virus. Heating the serum at $66^{\circ}C$, for 30 minutes brought about a complete loss of the neutralizing index of the serum. 7. No ions, as a cofactor, was incorporated to the inhibitory action of rabbit serum on the virus. 8. The inhibitory compound amays be found in a fraction of serum globulin.

• Korean Journal of Veterinary Service
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• v.14 no.1
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• pp.27-40
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• 1991

In order to investigate the biological properties, pathogenicity and immune responses in artficially infected SPF chickens with Avian infectious bronchitis virus that was isolated from chickens showing IB like signs in southern region of Chung buk. Results obtained throuth the experiments are summarized as follows. 1. From 15 IB suspected cases, two strains of IB virus were isolated, one each from the tracheas and lungs. 2. Infectious bronchitis specific embryo lesions were observed after four serial passages of the isolates in chicken embryos. 3. The field isolates and M-41 strain of IB virus interfered with the replication of Newcastle disease virus in chicken embryos. 4. When specific pathogen free chickens, two week old, were inoculated with the IB virus isolates, clinical respiratory signs as dyspnea, coughing were observed. Airsacculitis was observed by necropsy. 5. AGP antibody positive rates of inoculated SPF chickens were highest on day 14 and lowest on day 36, while HI antibody responses were detected on day 14 in all Groups, the reinoculated Group was shown highest titers. 6. By Indirect immunofluorescence antibody assay of artificially infected SPF chickens, the viral antigens were detected in tissues of larynx, trachea and lung on the 4 th to 7 th days post inoculation.

• Korean Journal of Veterinary Research
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• v.56 no.3
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• pp.189-192
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• 2016

The virus neutralization (VN) test was used to determine potency of the infectious bronchitis (IB) vaccine. The results of VN, hemagglutination inhibition (HI), and enzyme-linked immunosorbent assay (ELISA) were compared with those of the IBV M41. The $r^2$ values between VN and HI titers and the ELISA antibody titer were 0.8782 and 0.0336, respectively, indicating a high correlation between VN and HI, but not VN and ELISA. The Cohen's kappa coefficient between the VN titer of 2 $log_{10}$ and HI titer of 5 $log_2$ was 0.909. Our results showed that VN could be replaced with HI for testing the potency of IBV M41.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.405-410
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• 2005

To analyze and identify selected risk factors for infectious bronchitis virus (IBV) infection in the growing and laying period of laying-hen flocks, a longitudinal field study was conducted with 27 commercial flocks reared in three provinces of Korea during the period from May 2003 to April 2004. Using monitored data for IBV infection status among study flocks we computed the multivariate odds ratios (ORs) and their corresponding confidence intervals (CIs), and population attributable risks (PARs). Multivariate logistic regression showed significant risk increments for: continuous entry of chick (OR=1.9, 95% CI, 0.7-69.1) and operation years of the layer house greater than or equal to 5 years (OR=3.2, 95%CI, 1.6-389.9). No significant interaction was found between variables. The PAR suggested that continuous entry of chick (PAR=32%) and ${\geq}5years$ of house operation (PAR=84%) had the highest impacts on IB presence in laying-hen flocks under study. Of the two significant factors, however, operation year of the layer house lacks an easy applicability in preventing IB control strategies, and the possibility of confounder cannot be ruled out.

• Korean Journal of Veterinary Service
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• v.25 no.1
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• pp.87-96
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• 2002

In this study, we wanted to determine if the respirotropic JMK strain of infectious bronchitis virus(IBV), which has a spike glycoprotein gene that is 99% similar to the nephropathogenic Gray strain of IBV, could adapt and cause lesions in the kidney following intracloacal passage in chickens. Two day old specific pathogen free(SPF) cchickens were infected with Gray and JMK strains by the intraocular and cloacal route. Several tissue samples were collected at various times. Viruses were recovered from more tissues and earlier in the infection from chickens infected cloacally than chickens infected intraocularly. Virus was isolated from the kidney of chickens infected with Gray by the intraocular route and JMK by the intracloacal route, but not from chicken given JMK the intraocular route. Histopathologically, interstitial nephritis was observed in Gray infected chickens. However, viral RNA or antigen were not detected in the kidney by in situ hybridization and immunohistochemistry. We further passaged the JMK strain ten times in two day old SPF chickens using cloacal inoculation. We examined the virus titer and histopathological change in the kidney at each passage level. The amount of virus recovered from the kidney was stable throughout this serial passage and the passaged virus did not caused renal damage. Further, virus could not be isolated from the kidney when chickens were infected with the passaged virus by the intraocular route. We conclude that the JMK strain has a strict upper respiratory tract tropism since cloacal passage did not produce nephrotropism or nephropathogenicity.