It is inspiring to read news about the advancements being made in the fight against viral infections, including those against influenza and HIV. However, as comments to recent blog posts have reminded me, the struggle to develop antiviral therapies is highly complicated because viruses have the infamous tendency to mutate and adapt in their fight for survival and conquest of healthy cells. A major part of formulating and developing antivirals is trying to get some handle on a virus’s unpredictable nature, how it will change, and how these modified forms will strengthen our understanding of its interworkings.

Two recent reports have touched upon the challenges posed by mutating and resistant viruses, making vaccine formulation and development difficult. Scientists at the University of Alabama at Birmingham (UAB) have identified at least 14 “escape mutations” of HIV. These adaptations help keep the virus alive even after it interacts with the immunity molecules that usually affect it. In addition, influenza viruses continue to pose new challenges. A recent study shows that during the 2007-2008 influenza season, the resistance of the influenza A(H1N1) virus to the drug oseltamivir actually increased for the first time worldwide. Scientists are now predicting the resistance will increase for the 2008-2009 flu season, still in progress.

There is some good news on the vaccine front, however. With the help of genetically modified organisms and rapamycin (used in organ transplantation), researchers at The University of Texas Health Science Center in Houston have been able to boost the efficacy of the only approved tuberculosis vaccine for humans. The team was able to block the “evasive mechanisms” of Bacille Calmette-Guerin (BCG), which does not protect against tuberculosis completely. BCG evades immune-stimulating mechanisms such as antigens (molecular components of the bacteria); but the use of rapamycin allows the antigens to enter certain pathways that would allow the immune system to recognize them.