Safety evaluation of a recombinant myxoma-RHDV virus inducing horizontal transmissible protection against myxomatosis and rabbit haemorrhagic disease

We have recently developed a transmissible vaccine to immunize rabbits agai nst myxomatosis and rabbit haemorrhagic disease based on a recombinant myxo ma virus (MV) expressing the rabbit haemorrhagic disease virus (RHDV) capsi d protein [Barcena et al. Horizontal transmissible protection against myxom atosis and rabbit haemorragic disease using a recombinant myxoma virus. J. Virol. 2000;74:1114-23]. Administration of the recombinant virus protects r abbits against lethal RHDV and MV challenges. Furthermore, the recombinant virus is capable of horizontal spreading promoting protection of contact an imals, thus providing the opportunity to immunize wild rabbit populations. However, potential risks must be extensively evaluated before considering i ts field use. In this study several safety issues concerning the proposed v accine have been evaluated under laboratory conditions. Results indicated t hat vaccine administration is safe even at a 100-fold overdose. No undesira ble effects were detected upon administration to immunosuppressed or pregna nt rabbits. The recombinant virus maintained its attenuated phenotype after 10 passages in vivo. (C) 2000 Elsevier Science Ltd. All rights reserved.