Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo
https://pmc.ncbi.nlm.nih.gov/articles/PMC8595976/
Bisschop SPR, Peters A, Domingue G, Pearce MC, Verwey J, Poolman P. Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo. Gates Open Res. 2021 Dec 23;5:76. doi: 10.12688/gatesopenres.13212.3. PMID: 34859194; PMCID: PMC8595976.
Background This study determined whether the naturally attenuated, thermotolerant Newcastle disease vaccine virus I-2 could acquire virulence after five in vivo passages through SPF chickens.
Conclusions: These data, the issue of low passage titres with little or no virus isolation from brain tissues and the genomic copy approach suggest a need to amend Ph. Eur. v9.0 04/2013:0450, 2013 for naturally attenuated, low pathogenicity vaccine viruses such as I-2. From an international regulatory perspective, the study provides further definitive data demonstrating that Newcastle disease vaccine virus I-2 is safe for use.
Keywords: Newcastle Disease, I-2; passage, acquired virulence, European Pharmacopoeia, village chickens