Two Kentucky researchers who helped develop a vaccine to thwart a sexually transmitted disease in humans are using some of that knowledge to help an unlikely group of patients — manatees.
More than 15 years ago, Dr. A. Bennett Jenson and Shin-je Ghim of the University of Louisville were part of a team that helped develop a vaccine for the human papilloma virus, which causes cervical cancer. When a similar virus was identified in manatees, they were asked to help.
Ben Jenson, a pathologist, and Ghim, a microbiologist, first got involved in 1998, about two years after wart-like lesions were discovered on manatees in captivity. At the time, the researchers didn't really know what manatees were. Now they talk about them like friends.
"They're really gentle creatures," Jenson said Tuesday. "To swim with the free-ranging ones is just fantastic because they just want to know who you are."
West Indian manatees, or sea cows, are large aquatic mammals that live along the Atlantic coastline and in estuaries in Florida. They eat sea grass, weigh as much as 1,200 pounds and are most closely related to elephants. They migrate hundreds of miles a year, going as far north as Virginia in summer and wintering in warmer waters around Florida.
They are also an endangered species, with an estimated 3,500 to 4,000 alive today.
The wart-like lesions discovered in 1996 were identified as a manatee version of the papilloma virus.
In humans, papilloma viruses, known as HPV, cause genital warts and several kinds of cancers. The virus has received attention in recent years as the vaccine Jenson and Ghim helped develop, called Gardasil, was put on the market.
The vaccine, which has been heralded as first to prevent cancer, also generated controversy when state legislators across the country considered making it mandatory for middle school girls. In humans, HPV viruses are sexually transmitted.
In manatees, the virus is spread from mother to calf. When the manatees have lesions, it can also be spread from manatee to manatee when they snuggle and nuzzle.
The development of the lesions among captive manatees in the Crystal River area created a problem for wildlife officials. The manatees were in captivity to allow them to heal from injuries they had suffered in the wild. Officials planned to release them, but then they discovered the virus.
They didn't know how the animals had been exposed, said Nicole Adimey, a biologist with the U.S. Fish and Wildlife Service. And they didn't know whether the virus existed in the wild.
"We wanted to make sure it wasn't going to contaminate the wild population," Adimey said.
So Jenson, Ghim and other researchers in Florida began examining the virus in manatees.
Using computer programs, they determined that the virus probably developed around the same time manatees did.
This is common for papilloma viruses, Jenson said. In addition to studying the virus in people, he and Ghim have worked with many variations of the virus and helped develop vaccines for dogs, cats, cows, horses, snow leopards and dolphins.
They also studied the virus in manatees, going to Florida to examine the animals.
The two researchers created a vaccine for the virus in manatees and a test to see whether manatees had been exposed to it. And then the scientists tested manatees in the wild and in captivity.
They found that about 30 percent of migrating manatees had been exposed to the virus, compared with 35 percent to 40 percent of manatees in captivity, Jenson said.
"We showed that if you released the manatees from the estuaries, if you mix manatees, it's not going to be much different," Jenson said.
The lesions have never been seen on manatees in the wild. Researchers theorize that the stress of staying in waters that are too cold and not getting exercise from migration have weakened the manatees' robust immune systems.
"They're just like people who are overweight and aren't exercising," Jenson said.
This fall, the U.S. Fish and Wildlife Service awarded Jenson and Ghim a Manatee Conservation Award for their work.
The scientists hope the results of their research will persuade Fish and Wildlife to release captive manatees, who no longer have lesions, back into the wild. (According to Adimey, about 20 manatees have been quarantined.)
From their work with manatees, the two have learned more about the relationship between stress and papilloma viruses. They've also learned a lot about a mammal they hadn't encountered before.
Before the manatees, Ghim had worked only with small laboratory animals. The manatees were different: charming, gentle, kind.
"They are huge, you know, like elephants," she said. "I love those animals."