Developing a vaccine to protect against HIV in attempt to gain control of the AIDS pandemic is a top priority for researchers throughout the world. Extensive testing has been conducted with live vaccines to determine if immunization would be effective at prevention, but they are not suitable for human use due to the potential that the vaccine viruses could mutate and reacquire the ability to cause disease.
DNA vaccines offer a new possibility for treatment. The have the advantages of safety, low cost of production, and ease of use in field conditions due to their minimal need for refrigeration.
In the study the DNA of a simian/human immunodeficiency virus (SHIV) was made noninfectious by removing the gene that makes reverse transciptase (a protein the virus requires to replicate). Four macaques were injected with the noninfectious vaccine, while two control animals remained unvaccinated. Both groups were challenged with SHIV. All four of the immunized macaques became infected with the challenge virus, but three survived. The two control subjects died.
"The results showed strong evidence that this type of vaccine could prevent AIDS and established that a DNA vaccine, such as this one, could be used alone, without the need for booster doses with viral proteins, for large-scale immunization programs," say the researchers.
(D.K. Singh, Z. Liu, D. Sheffer, G.A. Mackay, M. Smith, S. Dhillon, R. Hegde, F. Jia, I. Adany, O. Narayan. 2005. A noninfectious simian/human immunodeficiency virus DNA vaccine that protects macaques against AIDS. Journal of Virology, 79. 6: 3419-3428.)
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Source:American Society for Microbiology