Safety concerns over attenuated herpesvirus vaccines
A paper on the recombination of attenuated vaccines to form virulent field viruses has been published, which raises safety concerns about using attenuated herpesvirus vaccines in veterinary medicine.
The paper, published in Science, raises safety questions after recombination between herpesvirus has been seen in vitro and in vivo under experimental conditions.
The abstract for the paper, co-authored by Sang-Won Lee, Philip F. Markham, Mauricio J. C. Coppo, Alistair R. Legione, John F. Markham, Amir H. Noormohammadi, Glenn F. Browning, Nino Ficorilli, Carol A. Hartley and Joanne M. Devlin reads as follows:
"Recombination between herpesviruses has been seen in vitro and in vivo under experimental conditions. This has raised safety concerns about using attenuated herpesvirus vaccines in human and veterinary medicine and adds to other known concerns associated with their use, including reversion to virulence and disease arising from recurrent reactivation of lifelong chronic infection. We used high-throughput sequencing to investigate relationships between emergent field strains and vaccine strains of infectious laryngotracheitis virus (ILTV, gallid herpesvirus 1). We show that independent recombination events between distinct attenuated vaccine strains resulted in virulent recombinant viruses that became the dominant strains responsible for widespread disease in Australian commercial poultry flocks. These findings highlight the risks of using multiple different attenuated herpesvirus vaccines, or vectors, in the same populations."
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Defra has published guidance for the vet sector ahead of a proposed UK-EU Sanitary and Phytosanitary agreement.
