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Title: Sequence analysis of CVI988-based vaccine, pCVI988-699-2-RV that has undergone a reversion to virulence

Author
item ROJAS-AMORTEGUI, JULIANA - University Of Delaware
item DONG, HUIMIN - University Of Delaware
item KATNENI, UPENDRA - University Of Delaware
item GADDAMANUGU, SYAMSUNDAR - University Of Delaware
item TAVLARIDES-HONTZ, PHAEDRA - University Of Delaware
item PARCELLS, MARK - University Of Delaware
item Abdo, Zaid
item Spatz, Stephen

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2014
Publication Date: 7/20/2014
Citation: Rojas-Amortegui, J., Dong, H., Katneni, U., Gaddamanugu, S., Tavlarides-Hontz, P., Parcells, M.S., Abdo, Z., Spatz, S.J. 2014. Sequence analysis of CVI988-based vaccine, pCVI988-699-2-RV that has undergone a reversion to virulence. In: Proceedings of the 10th International Symposium on Marek's Disease and Avian Herpesviruses, July 20-23, 2014, East Lansing, Michigan. p. 39.

Interpretive Summary:

Technical Abstract: In our safety evaluation of CVI988-699-2delta, a vaccine derived from a bacterial artificial chromosome (BAC)-based infectious clone of low passage CVI988, we found that the virus reverted to virulence during a safety trial using specific pathogen free (SPF) leghorn chickens. To determine changes in the sequence accompanying the reversion to virulence, we conducted a study using SPF chickens infected with a high dose of pCVI988-699-2. In this study, we were able to isolate a BAC-based infectious clone from a kidney-localized lymphoma. The infectious clone of this virus (pCVI988-699-2RV, for reverted to virulence) and pCVI988-699-2 were compared by Ilumina 454 pyrosequencing. Only four mutations differed among the two (182,025 bp) genomes. A synonymous mutation was identified in UL19 encoding the major capsid protein. A non synonymous (Thr-Ser) mutation was identified in the UL36 gene encoding the large tegument protein. One intergenic mutation between UL34 and UL35 was also identified. Mutations (A to G) were identified in both copies of the telomerase ribonucleic acid (vTR) within the CR2 domain.