title: Characterization of a recombinant Newcastle disease virus vaccine strain.
abstract: A recombinant La Sota strain (KBNP-C4152R2L) in which fusion (F) and hemagglutinin-neuraminidase (HN) genes were replaced with those of a contemporary genotype VIId virus, KBNP-4152, has been developed. To attenuate the virulence of the recombinant strain, the F cleavage motif was mutated from (112)RRQKR(116) to (112)GRQAR(116), and to reduce pathogenic instability, a codon which does not allow changes to basic amino acids by single point mutation was inserted at codon 115. In addition a six-nucleotide sequence was inserted into the intergenic region between matrix protein and F genes for attenuation without breaking the "rule-of-six." The HN protein length was increased from 571 to 577 as a marker. Serological tests revealed that the antigenicity of KBNP-C4152R2L was similar to that of KBNP-4152 but distinct from that of the La Sota strain. KBNP-C4152R2L was avirulent (intracerebral pathogenicity index, 0.0; mean death time, >168 h) and stable in pathogenicity through in vivo passages. The killed oil emulsion of and live KBNP-C4152R2L were completely protective against mortality and egg drop caused by virulent strains, and KBNP-C4152R2L was applicable to in ovo vaccination. Therefore, KBNP-C4152R2L is a promising vaccine strain and viral vector in terms of antigenicity, productivity, safety, and pathogenic stability.
authors.affiliation: Zoonotic Disease Institute, Seoul National University, San 56-1, Shillim-Dong, Gwanak-Gu, Seoul, Korea. kwonhj01@snu.ac.kr
authors.forename: Sun-Hee
authors.initials: SH
authors.lastname: Cho
authors.forename: Hyuk-Joon
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Tae-Eun
authors.initials: TE
authors.lastname: Kim
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Han-Sang
authors.initials: HS
authors.lastname: Yoo
authors.forename: Man-Hoon
authors.initials: MH
authors.lastname: Park
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Park
authors.forename: Sun-Joong
authors.initials: SJ
authors.lastname: Kim