Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]

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. Methods Study design was to international requirements including European Pharmacopoeia, Ph. Eur., v9.0 04/2...

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Autores principales:	Shahn P.R. Bisschop, Andrew Peters, Gil Domingue, Michael C. Pearce, Jeanette Verwey, Petrus Poolman
Formato:	article
Lenguaje:	EN
Publicado:	F1000 Research Ltd 2021
Materias:	Medicine R
Acceso en línea:	https://doaj.org/article/ba3df369905e4d888c9a310b26eda6d0
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spelling	oai:doaj.org-article:ba3df369905e4d888c9a310b26eda6d02021-11-22T12:41:08ZNewcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]2572-475410.12688/gatesopenres.13212.2https://doaj.org/article/ba3df369905e4d888c9a310b26eda6d02021-11-01T00:00:00Zhttps://gatesopenresearch.org/articles/5-76/v2https://doaj.org/toc/2572-4754Background 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. Methods Study design was to international requirements including European Pharmacopoeia, Ph. Eur., v9.0 04/2013:0450, 2013. I-2 Working Seed (WS) was compared with five-times-passaged I-2 WS (5XP WS) in intracerebral pathogenicity index (ICPI), Fo cleavage site sequencing and Safety tests. Results The first passage series used a 50% brain: 50% tracheal tissue challenge homogenate and was unsuccessful as I-2 was not detected after the fourth passage. A second passage series used 10% brain: 90% tracheal tissue homogenates. I-2 was isolated from tracheal tissue in each passage. However harvested titres were below the minimum challenge level (107 EID50) specified for the ICPI and Safety tests, possibly reflecting I-2’s inherently low pathogenicity (interestingly caecal tonsils yielded significant titres). Given this the WS and 5XP WS comparisons proceeded. ICPI values were 0.104 and 0.073 for the WS group and the 5XP WS group respectively confirming that I-2, whether passaged or not, expressed low pathogenicity. F0 amino-acid sequences for both WS and 5XP WS were identified as 112R-K-Q-G-R-↓-L-I-G119 and so compatible with those of avirulent ND viruses. In safety, no abnormal clinical signs were observed in both groups except for two chicks in the 5XP WS group, where one bird was withdrawn due to a vent prolapse, and another bird died with inconclusive necropsy results. 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.Shahn P.R. BisschopAndrew PetersGil DomingueMichael C. PearceJeanette VerweyPetrus PoolmanF1000 Research LtdarticleMedicineRENGates Open Research, Vol 5 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R
spellingShingle	Medicine R Shahn P.R. Bisschop Andrew Peters Gil Domingue Michael C. Pearce Jeanette Verwey Petrus Poolman Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
description	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. Methods Study design was to international requirements including European Pharmacopoeia, Ph. Eur., v9.0 04/2013:0450, 2013. I-2 Working Seed (WS) was compared with five-times-passaged I-2 WS (5XP WS) in intracerebral pathogenicity index (ICPI), Fo cleavage site sequencing and Safety tests. Results The first passage series used a 50% brain: 50% tracheal tissue challenge homogenate and was unsuccessful as I-2 was not detected after the fourth passage. A second passage series used 10% brain: 90% tracheal tissue homogenates. I-2 was isolated from tracheal tissue in each passage. However harvested titres were below the minimum challenge level (107 EID50) specified for the ICPI and Safety tests, possibly reflecting I-2’s inherently low pathogenicity (interestingly caecal tonsils yielded significant titres). Given this the WS and 5XP WS comparisons proceeded. ICPI values were 0.104 and 0.073 for the WS group and the 5XP WS group respectively confirming that I-2, whether passaged or not, expressed low pathogenicity. F0 amino-acid sequences for both WS and 5XP WS were identified as 112R-K-Q-G-R-↓-L-I-G119 and so compatible with those of avirulent ND viruses. In safety, no abnormal clinical signs were observed in both groups except for two chicks in the 5XP WS group, where one bird was withdrawn due to a vent prolapse, and another bird died with inconclusive necropsy results. 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.
format	article
author	Shahn P.R. Bisschop Andrew Peters Gil Domingue Michael C. Pearce Jeanette Verwey Petrus Poolman
author_facet	Shahn P.R. Bisschop Andrew Peters Gil Domingue Michael C. Pearce Jeanette Verwey Petrus Poolman
author_sort	Shahn P.R. Bisschop
title	Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
title_short	Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
title_full	Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
title_fullStr	Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
title_full_unstemmed	Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
title_sort	newcastle disease vaccine virus i-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]
publisher	F1000 Research Ltd
publishDate	2021
url	https://doaj.org/article/ba3df369905e4d888c9a310b26eda6d0
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Newcastle disease vaccine virus I-2 fails to acquire virulence during repeated passage in vivo [version 2; peer review: 1 approved, 2 approved with reservations]

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