While a new DNA
vaccine may not be able to prevent HIV infection, it could protect against
progression to full-blown AIDS. Researchers from Kansas report their findings
in the March 2005 issue of the Journal of Virology.
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.
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 non-infectious by removing the gene that makes reverse
transciptase (a protein the virus requires to replicate). Four macaques were
injected with the non-infectious 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
(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.)