doi:10.1016/j.vaccine.2004.06.032
Recombinant viruses obtained from co-infection in vitro with a live vaccinia-vectored influenza vaccine and a naturally occurring cowpox virus display different plaque phenotypes and loss of the transgene
Hilde Hansena, 1, Malachy Ifeanyi Okekea, Øivind Nilssenb and Terje Traavika, c,*
aDepartment of Microbiology and Virology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway
bDepartment of Medical Genetics, University Hospital of Northern Norway, N-9038 Tromsø, Norway
cNorwegian Institute of Gene Ecology, Tromsø Science Park, N-9291 Tromsø, Norway
Received 20 November 2003; revised 5 May 2004; accepted 16 June 2004. Available online 29 July 2004.
Abstract
Some poxviruses are very attractive as transgenic vaccine vectors for humans, domestic animals and wildlife. Poxviridae family members circulate in different ecosystems and parts of the world, providing a pool of possible recombination partners for released or escaped genetically modified poxviruses. We performed in vitro double infections with a vaccinia virus strain Ankara (MVA) vectored influenza vaccine and a cowpox virus isolate from Norway, isolated hybrids, and further analyzed three hybrid viruses with different plaque phenotypes. One of the hybrids was genetically unstable, and during adaptation to new host cells its MVA derived influenza gene was deleted at a high frequency. This is significant in a risk assessment context, since the transgene would be the only logical tag for monitoring unwanted spread and non-target effects of a vaccine virus. Putative recombination events involving genetically modified and naturally occurring viruses should be included in health and environmental risk assessments.
Keywords: Poxvirus; Orthopoxvirus; MVA recombinant vaccines; Risk assessment; Safety
*Corresponding author. Tel.: +47 77 644379; fax: +47 77 644488.
E-mail address: terjet@genok.org (T. Traavik).
1 Present address: Institute of Marine Biotechnology, Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway.