Progress towards using recombinant myxoma virus as a vector for fertility control in rabbits.

The history of myxoma virus, its use in Australia as a mortality agent and the development of the virus as a vector for controlling fertility in wild rabbit populations in Australia is reviewed. Myxoma virus recombinants have been constructed to express model antigens. Four potential insertion sites in the genome have been identified and two have been used to construct single and double recombinant viruses expressing Escherichia coli enzymes beta-galactosidase and beta-glucuronidase. Another recombinant expressing an influenza virus haemagglutinin gene (A/PR8/34) induced high and sustained antibody responses following intradermal inoculation in rabbits. To demonstrate the potential of introducing a recombinant virus into wild rabbit populations, a virus containing a natural deletion was released at four field locations. Preliminary analysis of the data has shown that the introduced virus spread well on 3 of the 4 locations. The steps being taken to address the ethical and safety implications of the introduction of a recombinant virus into the field are discussed.