Porcine vaccines with human potential

by Joseph Carlson

If Anuradha Subramanian is successful, the livestock of the 21st century will provide not only food but also vaccines for humans and other animals.

Subramanian, an assistant professor of biosystems and agricultural engineering, is working on a new project to produce a vaccine to fight a common disease in pigs, Porcine Respiratory and Reproductive Syndrome. But PRRS—pronounced “purse”—is just the test subject for a cutting-edge technique that employs DNA recombination and the bellies of mammals as bioreactors to produce proteins and other essential biological components.

It's a long road to that point, however, and Subramanian's work faces many challenges. Researchers in the Department of Veterinary Pathobiology had already accomplished the difficult first step, isolating the virus's genetic code. So rather than reinventing the wheel, Subramanian obtained a copy of the PRRS nucleotide sequence, the genetic recipe for the virus.

Department researchers had been working on decoding the DNA of the virus for years before Subramanian had embarked on her project, says Kay Faaberg, a senior research associate and head of a project studying PRRS. In fact, several scientists shared Subramanian's theory of using DNA technology to find a vaccine.

"There are several researchers who have done this before,” Faaberg says. “It's just a question of being able to create the system in order to produce these things."

Certain proteins are responsible for the creation of antibodies that fight the virus. A vaccine simply tells the body how to produce the biological weapons that fight the virus; these proteins carry the instructions. Ironically, the PRRS virus carries the means of its own self-destruction, the protein that instructs the body how to produce the killer antibodies. It's just a matter of getting enough of the protein to produce an adequate level of antibodies.

"There are many diseases that affect humans and animals, and what you need are proteins,” Subramanian says. “Nucleic acids help in making many copies of the virus, and the proteins create antibodies."

Her experiment separates the proteins in the virus from the nucleic acids that help it to reproduce. Once Subramanian has isolated the protein, she hopes to manipulate its DNA so that it will produce the vaccine after it is inserted into the genetic sequence of other cells.

The next step will be to insert the proteins into an animal, causing it to reproduce the compound inside its body. The animal's milk will then contain ample amounts of the protein, which can be filtered out using noninvasive techniques that do not harm the animal.

If her project is successful, Subramanian hopes it can be applied to human needs as well. Hemophiliacs, for example, could benefit from it without depleting the already-low blood supply. The chemical they need could simply be produced by animals, she says.

Right now, creating vaccines and compounds for human use is a long way off. But Subramanian is encouraged by the support she's received from the Pork Producers Council for her efforts to find a vaccine for PRRS. With that support, she hopes to further her research and develop the technique for use in other areas of genetic science.

"There is a need for research to better understand this disease,” she says.

For more information see www.bae.umn.edu.