Milestone demonstration validates effectiveness of DNA vaccine technology in large mammals

Why is registration of a new equine vaccine for West Nile virus generating excitement among biomedical researchers? It represents a breakthrough in DNA vaccine technology, demonstrating this new class of vaccines is viable for human use.

Many pathologists and clinical laboratory professionals will find this news noteworthy for several reasons. First, it is an important milestone in the use of molecular technology to advance genetic medicine. Second, wider use of DNA vaccines will serve the goal of preventive healthcare. Third, should DNA vaccines eventually find a role in protecting humans from a wide spectrum of diseases, this, in turn, will significantly change the role and frequency of laboratory testing for these diseases. Along with other uses, it is because DNA vaccines can target cancers as well as infectious diseases.

Previously, DNA vaccines had only been effective in animals no larger than a rat, noted Dr. Hsien-Jue Chu, Executive Vice President for the Fort Dodge Animal Health division of Wyeth,  the vaccine developer, in the March 1, 2009 issue of Genetic Engineering & Biotechnology News (GEN). Success in large animals came when the researchers added an immune-modulator to the plasmid DNA, which probably enabled DNA injected intramuscularly to target cells more effectively, he explained.

While DNA vaccine is no more effective in protecting against disease than traditional vaccine, it does have multiple advantages, according to experts commenting in GEN’s DNA Vaccine Corporate Roundtable.

  • It allows rapid manufacture ramp up of different vaccines from a single technology platform. The only thing that changes is the type of DNA inserted into the process.
  • DNA vaccines generate both antibody and T-cell responses, making them viable for addressing a broad range of diseases.
  • Because enhancing T-cell responses broadens the immune response, this benefit greatly expands use of DNA vaccines beyond prevention to therapy. In turn, that significantly expands the market size because DNA vaccines can become therapies for infectious diseases and cancer.
  • Expansion of the market for vaccines to include therapeutic applications would renew investor interest in vaccine development. That’s because, aside from the recent exception of Gardasil, the vaccine business has become a low margin investment, despite vaccines’ success in improving survival.
  • DNA vaccines do not elicit antivector immune response. This means a vaccine could be used over and over again as a maintenance booster without losing effectiveness. An obstacle to creating vaccines for viruses is pre-existing immunity to viral vectors, which is why there are no vaccines for malaria, tuberculosis and AIDS. According to an article in the May 11, 2009, issue of Nature , molecularly engineered viruses with pathogen-specific gene inserts may offer a way around this problem.
  • DNA vaccines are fairly stable compared to live or attenuated organism vaccines, possibly allowing them to be stored at room temperature and taken to areas of the world without refrigeration.
  • Finally, from a patient safety perspective, DNA vaccine would be safer than traditional vaccines, because it is not made from live organisms.

Having demonstrated effectiveness in horses for the West Nile Virus, DNA vaccine technology still has many hurdles before it is appropriate for human use. However, because DNA vaccines have the potential to be used in therapy, experts believe that ample venture capital will be available for ongoing research and development.

For clinical laboratory managers and pathologists, the rapidly-developing molecular technology supporting DNA vaccine development is a reminder of how fast new genetic medicine may revolutionize long-standing clinical practices. In turn, laboratory medicine will undergo its own rapid evolution as it responds to these new medical advances.

Related Information:

DNA Vaccines Inch Toward Human Use

Vaccines: Engineering immune evasion