THE POTENTIAL OF MURINE CYTOMEGALOVIRUS AS A VIRAL VECTOR FOR IMMUNOCONTRACEPTION

Wild populations of house mice (Mus domesticus) regularly undergo popu lation eruptions in the cereal growing regions of S.E. Australia, caus ing significant damage to crops. Rodenticides are costly and are of li mited usefulness, and the need for a biological control agent is widel y recognized. The options for the use of an infectious agent to contro l mouse populations are considered. The three main types are: infectio us agents which establish lethal infection; those which directly inter fere with fertility; and recombinant virus vectors encoding fertility- associated proteins such as zona pellucida or sperm antigens in order to induce immunocontraceptive responses in infected mice. Ectromelia, a murine pox virus, has the potential for reducing mouse populations b y lethal infection but it is not present in wild mice in Australia. Th e disadvantages of using ectromelia are that it would pose a significa nt threat to colonies of laboratory mice, there appears to be substant ial innate resistance in Australian wild mice and it may not be entire ly mouse-specific, thus placing native rodents at risk. A number of fa ctors influencing the selection of a virus as a vector for immunocontr aception are discussed. The mouse-specific murine cytomegalovirus (MCM V) fits most of these criteria. Infection with MCMV is already widespr ead in Australia with 80-90% of Mus domesticus tested being seropositi ve. It is a large DNA virus which establishes persistent, non-lethal i nfection, it is a suitable vector for the insertion of foreign genes a nd has a number of properties, including the capacity for superinfecti on, that should assist the recombinant virus to persist in wild mouse populations and induce an immunocontraceptive effect.