UNSW scientists are raising concerns over the unpredictable nature of a contraceptive vaccine that aims to control populations of wild animals, such as rabbits and foxes.
Writing in the latest issue of the journal, Reproduction, UNSW genetics expert Professor Des Cooper warns that the immuno-contraception method is not fully effective and is manipulating natural reproduction in ways that can't be predicted or controlled.
Professor Cooper also raises concerns that individuals that survive the vaccine may be more likely to carry infectious diseases with the potential to affect other animals.
An immuno-contraceptive vaccine causes an animal's immune system to produce antibodies that act against some essential event or structure in the reproductive process. The antibodies can act against sperm, eggs or reproductive hormones, which prevent either fertilization or the production of sperm and ova.
Proponents of the technique, which was first tested nearly 20 years ago, regard it as more humane than the conventional methods of controlling wildlife populations, such as shooting, trapping, poisoning or viral diseases. It has drawn support from some politicians and animal-welfare agencies.
An expert in mammal reproduction, Professor Cooper, of the UNSW School of Biological, Earth and Environmental Sciences, questions immuno-contraception on three grounds.
"Firstly, immuno-contraceptives are ineffective against substantial minorities of animals, probably for genetic reasons," Professor Cooper says. "If so, the genes responsible for this lack of response will be passed on to offspring. Within a few generations most of the population will be unresponsive to the immuno-contraceptive, so its effectiveness as a form of birth control is likely to be short-lived."
His second concern is that the technique is effectively a form of genetic engineering: "Immuno-contraception alters the gene pool of the targeted species because those animals who are unresponsive are genetically unusual individuals," he says.
"The third concern is that animals are suffering side-effects from multiple injections and adjuvant substances (catalysts that modify the action of other agents) designed to boost the effectiveness of immuno-contraceptives.
"The most commonly used adjuvant, Freund's adjuvant, also induces a range of undesirable side-effects and its use is being challenged on animal-welfare grounds."
Read the scientific paper online
Desmond W Cooper and Elisabeth Larsen, Immuno-contraception of mammalian wildlife: ecological and immuno-genetic issues, Reproduction (2006) 132 821-828
Media Contacts: Professor Des Cooper, 0437 677 269. Dan Gaffney, Media Office, 0411 156 015.