Thanks for your letter of February 2nd, regarding fertility control for rabbits. Whether or not it is possible to introduce a viral-vectored immunocontraceptive into the Australian rabbit population in the near future is a question I cannot answer. Hugh-Tyndal Biscoe would have a more accurate idea what the regulatory hurdles for such an approach might be in Australia. I can tell you that the very idea of a viral-vectored immunocontraceptive here in the U.S. is totally out of the question for regulatory reasons. Our Food and Drug Administration (FDA) will not permit such an approach under almost any circumstances. Even oral delivery is out of the question unless the immunocontraceptive is species-specific, something that represents a huge scientific hurdle. Add to that the concern that viruses mutate rapidly and may be able to infect something other than the target species, and that no known immunocontraceptive is species-specific (and ours can in fact contracept humans) and we have sound reason for never even considering such an approach.

Having painted such a pessimistic picture, I come back to the dismal prospect of developing a good contraceptive for something like rabbits. Frankly, one of the only solutions I see is to stop killing the dingoes in Australia, but maybe that isn’t even enough, even if there would be no objections from wool growers. Perhaps your regulatory agencies might approve an oral contraceptive that could be placed below the ground in burrows. There are steroids that will work, but they will pass through the food chains of predators and scavengers, but if predators have not been able to control rabbits anyway, perhaps this is not a concern.