But here’s the catch: Vaccinated deer test positive for TB.
By: David Campbell
SpayVac is an experimental birth-control vaccine that has proven effective on captive white-tailed deer at Penn State University, but Princeton Township won’t touch the stuff with a 10-foot pole.
In the 1990s, Canadian researcher Bob Brown of Dalhousie University and co-founder of ImmunoVaccine Technologies, the maker of SpayVac, developed a contraceptive vaccine for gray seals in the Northwest Atlantic.
One inoculation with SpayVac lasts six years or more in seals, and tests have shown the vaccine to be effective up to two years in fallow deer. Preliminary results on captive white-tails at Penn State have shown the vaccine to last up to three years.
Some who oppose the township’s use of rifles and captive-bolt guns to trim the deer herd say the one-shot vaccine could be the answer to problems with conventional vaccines often cited by supporters of deer-management by lethal means.
The conventional vaccine it’s called porcine zona pellucida (PZP), it’s made from purified pig ovaries and it’s the main ingredient in SpayVac has been around for more than 30 years.
The vaccine works well, except for one catch booster shots must be administered annually.
In field tests in New Jersey and New York State, treated animals couldn’t be found again the next year for follow-up shots.
Based on these findings, officials in Princeton Township ruled out a test program of their own and instead brought in Connecticut-based wildlife-management firm White Buffalo, which is culling the herd with rifles and captive-bolt guns. Captive-bolt guns are slaughterhouse devices that kill with a 4¾-inch retractable bolt to the animal’s head.
Why, then, does the township want nothing to do with SpayVac, a single-dose vaccine that could get around the problem of truant deer and perhaps relieve some of the controversy surrounding the deer issue by at least exploring nonlethal options?
Because deer vaccinated with SpayVac test positive for tuberculosis, a contagious and potentially lethal bacterial infection in animals and humans that primarily attacks the lungs.
"It can’t be used," said Tom Poole of the township’s wildlife committee and a drafter of Princeton’s deer-management program. "The FDA is never going to approve something for a game animal that will be inoculated one day and shot and eaten the next. Anyone who says SpayVac is the answer is crazy."
Here’s how the vaccine works. The pig antigen PZP causes a treated female mammal to produce antibodies that adhere to the outer membrane of her eggs and prevent sperm from binding.
According to Jay Kirkpatrick of ZooMontana, one of the two suppliers of PZP to zoos and wildlife preserves worldwide, the antigen acts much like a locksmith that changes the lock on deer sperm, the "molecular keys," so they cannot gain access.
That’s because when the female produces antibodies to destroy the pig antigen, the "keyhole" is changed so that it will recognize and admit only sperm from a pig.
Mr. Kirkpatrick said conventional PZP has proven to be an effective contraceptive on more than 95 different animal species in over 80 different zoos and preserves around the world. The only animals it won’t work on, of course, are pigs.
The ingredient in SpayVac that makes it good with only one dose is the adjuvant, a stimulant that prompts a powerful immune response in the animal and thereby greatly enhances the vaccine’s potency.
It is the adjuvant specifically Freund’s Complete Adjuvant (FCA), which literature by SpayVac’s manufacturer calls "the gold standard" of adjuvants because it is so widely used in vaccine research that causes deer to test positive for tuberculosis, said Professor Allen Rutberg of Tufts University School of Veterinary Medicine and senior scientist for wildlife and habitat protection for the Humane Society of the United States.
But Professor Rutberg, who is working with Penn State researchers on the white-tail trials, said worries over tuberculosis are an "outdated concern."
Deer don’t get the bacterial infection from SpayVac but only test positive for it, which is a crucial distinction, he said. FCA, which Professor Rutberg said has been around since the 1930s, carries dead fragments of tuberculosis antibodies, fragments that "do give a false positive, but they do not cause TB," he said.
And besides, the professor said, worries over the bacterial infection are now a "non-issue" because in new clinical trials on Penn State white-tails the Freund’s adjuvant has been replaced with an equally effective but TB-free adjuvant.
SpayVac manufacturer ImmunoVaccine Technologies expects to finish those trials and obtain FDA approval for the vaccine in three to five years, Professor Rutberg said.
Mark Fraker of the Canadian research firm TerraMar Environmental Research Ltd., which is overseeing field and captive studies for its partner ImmunoVaccine, said the FDA has been heavily lobbied to approve a one-shot vaccine like SpayVac and it "would be very happy" to approve one for commercial use.
"It works. There’s no doubt in my mind about that," Mr. Fraker said. However, he said, around $2 million must be rounded up before FDA trials can begin.
"This is not going to be a big money-maker for anybody," Mr. Fraker said. "The market for this is going to be very, very small. This is not Viagra."
Meanwhile, Princeton Township’s deer cull and the sometimes shrill reactions it engenders continues.
Mr. Poole said he is aware of the new trials, and noted that despite federal approval being years off, "Advocates here in New Jersey feel it’s the answer to the deer problem."
Professor Rutberg said those who claim killing deer is the only solution have taken the TB scare "and run with it" as a handy justification of their views.
Nina Austenberg, director of the Humane Society’s Mid-Atlantic Regional Office, said the society has wanted to conduct immunocontraceptive field tests in the township for years but has never made a proposal because of resistance from the Township Committee.
"The committee is very top-heavy on lethal," Ms. Austenberg said. "Princeton Township is the most frustrating place I’ve ever worked with among four states. Somehow, they just don’t get it."
Princeton Township Mayor Phyllis Marchand said the committee always has been open to proposals for vaccination pilot programs.
"We are as anxious now as we were before to be a place where the immunocontraceptive could be tested," Mayor Marchand said. "As we have said before, we would welcome an opportunity to be in the forefront of any kind of wildlife management that would make our community safer and healthier."
Mr. Kirkpatrick of ZooMontana, who has worked with government organizations around the globe, said he wants nothing to do with domestic deer any more.
"It has become so irrationally political that I have no time for it," he said. "Why should I walk into these places where there is nothing but irrationality, where the politics is so thick you could cut it with a knife?"