to specifically recognize and bind to messenger RNA sequences that encode viral proteins. Once bound, the antisense DNA molecules make the messenger RNA molecules unreadable by the protein-synthesizing machinery. The potential use of antisense technology against HIV and other viruses has generated much excitement in the scientific community. Antisense is a highly specific strategy that holds the additional promise of circumventing viral latency. In fact, antisense technology is only useful when cells pass from latent infection to actively producing viral particles.
In theory, all cells can take up the antisense molecules. As long as a cell remains latently infected, the antisense molecules would serve no purpose, but as soon as a latently infected cell starts expressing viral genes, the antisense molecules would effectively prohibit the manufacture of proteins from those genes. Without viral proteins, new viral particles cannot be made. So far, antisense technology has proved successful in the laboratory. Soon this technology will be used in human trials, where it is hoped, it will reduce the level of viral reproduction as well.
Assuming a virus reaches the stage where it does manufacture proteins, the assembly and release of newly formed viral particles would constitute the last opportunity for drug intervention. Here researchers are testing the potency of a class of chemicals called interferons, which are normally secreted by virally infected cells. Although no one is sure of the mechanism, scientists have found that in the laboratory the specific compound called alpha-interferon inhibits HIV from appropriately assembling and budding out of the infected cell. The drug has been associated with some negative side effects, so its ultimate appropriateness for human use remains to be determined in clinical trials.
In addition to drugs that interfere specifically with the viral life cycle, many new antibiotics and antimicrobial agents have been developed to fight the specific opportunistic infections that people with AIDS fall prey to (see Table 3.4). Despite the difficulty of finding a vaccine to prevent initial infection, physicians and researchers are optimistic that in the future AIDS patients will be healthier and more comfortable than in years past. In the years to come, AIDS may be a chronic disease, and people infected with HIV may be able to live with the infection for the rest of their lives. The new constellation of antiviral drugs and therapeutics directed against opportunistic infections may well mean that the relationship between infection and disease will change. A person who is seropositive for HIV may never develop AIDS or may remain disease free for many years.