• Korean Journal of Poultry Science
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• v.38 no.2
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• pp.97-104
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• 2011

We conducted a 10-month (March to October 2009) surveillance of Newcastle disease virus (NDV) in 13 slaughterhouses in Korea. NDV was isolated in 13.0%, 13.3%, 16.0%, and 10.8% of chicken farms, transport vehicles, hang rooms, and chilling water, respectively. Of NDV isolates from slaughterhouses, 37% were isolated in July. All NDV isolates were determined to be lentogenic viruses by RT-PCR-based pathotyping, and all NDV isolates had the $^{112}GKQGR/L^{117}$ motif at the cleavage site of the F protein. Phylogenetic analysis based on the hypervariable region of the F protein gene classified all 25 NDV isolates examined into genotype I within class II. Of these, 24 were clustered together with the NDV V4 strain, while the remaining isolate was placed in the cluster belonging to the NDV Ulster 2C strain. Our results indicate that lentogenic NDV was a high-frequency contaminant in the serial process of ranging live birds to slaughtering at slaughterhouses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.124-133
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• 2011

Bacterial blight (BB), cuased by the vascular pathogen Xanthomonas oryzae pv. oryzae, is one of the major threats in rice fields worldwide. In Korea, two resistance genes against BB, Xa1 and Xa3 had been intensively used for developing high quality japonica rice cultivars. Those traditional resistance sources have being rapidly ified by the adopting of BB pathogen through mutations of the corresponding avr-genes, such as K3a exhibiting high compatibility to both Xa1 and Xa3. To expanding genetic resource against BB in Korea, the Suweon506, an introgression line between a Korean japonica cultivar, Hwaseong and a wild relative, Oryza minuta, was be subjected for genetic analysis owing to the BB resistance. Through association analyses between the pathotyping and genotyping results for each $F_2$ progenies, derived from a cross between Suweon506 and a Tongil type cultivar, Milyang23, a major resistant dominant gene is localized on the subterminal region of rice chromosome 4, where at least three BB resistancde genes, Xa1, Xa2, and Xa22, were reported previously.

• Korean Journal of Poultry Science
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• v.44 no.2
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• pp.93-102
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• 2017

A duplex RT-PCR (dRT-PCR) assay was developed for the simultaneous detection and discrimination of non-virulent and virulent Newcastle disease virus (NDV) in a single PCR tube. Primers targeting the large polymerase protein (L) gene and the fusion protein (F) gene of NDV were designed to detect all NDVs (by common type PCR primers) and virulent NDVs (by pathotype PCR primers), respectively and evaluated experimentally with reference NDV strains and other poultry viral pathogens. PCR products of the expected size of 386 bp were amplified from all NDV samples whereas PCR products of the expected size of 229 bp were amplified from virulent NDV samples alone. Cross reaction was not observed with other avian viral pathogens. The detection limit of NDV by the dRT-PCR was estimated to be $10^3$ 50% egg infectious dose/0.1 mL. In the dRT-PCR using field isolates of NDV, the pathotype PCR primers detected specifically all of virulent field isolates of NDV from Malaysia, Pakistan and China whereas common type PCR primers detected 94.4% (51/54) of field isolates of NDV from China. Three Chinese NDV isolates with false negative result were non-virulent viruses. Our results indicate that the dRT-PCR might provide a rapid and simple tool for rapid simultaneous detection and discrimination of non-virulent and virulent NDVs. Therefore the developed dRT-PCR assay provides a powerful novel means for the rapid diagnosis of Newcastle disease.