In many domestic and exotic animal species, immunization with killed or live infectious organisms is an effective, low-risk, and relatively inexpensive method of protection against common infectious diseases. But they haven't worked in marine mammals and this is of concern to Navy veterinarians at Space and Naval Warfare Systems Center San Diego who teach, care for, breed, and indeed pamper nearly a hundred marine mammals, including sea lions and dolphins. These animals are trained to perform swimmer defense, deep-water object recoveries, and mine countermeasures. They are healthy and well cared for, and the loss of just one of these carefully nurtured animals is a costly and tragic event.
A newly developed type of vaccine is the plasmid DNA vaccine, which avoids the use of killed or live infectious organisms and has fewer side effects. These vaccines work by inoculating a small piece of gene-encoding DNA which, when made into protein by the host animal, can stimulate an immune response. They are proven effective in many domestic animals as well as exotic animal species, but have never been investigated in marine mammals.
Recently, the Office of Naval Research provided funding to identify major infectious threats to wild and semi-domesticated dolphins and sea lions, to construct new plasmid vaccines that might stem epidemic disease, and to develop ways of measuring immune responses to these new vaccines.
Dr. Linda Chrisey and Dr. Robert Gisiner, ONR program managers on the study, are convinced the answer is out there. "Vaccination of individual animals within a population is perhaps the single most effective preventive medicine tool," Dr. Chrisey says. "The studies ONR is supporting may soon allow us to better protect marine mammals from infection."