Why are there no antiviral drugs available? What issues affect the development of antiviral drugs?

Common mutations of viruses also make it difficult retain a generally useful drug available for any amount of time.

Researchers at McMaster University have discovered a critical step in the immune system's recognition of DNA viruses. The study published today by the scientific journal Nature Immunology found that a protein, previously known to be involved in metabolism, is critical for the detection of the viruses. The co-authors are Brian Lichty and Yonghong Wan, both professors of pathology and molecular medicine for McMaster's Michael G. DeGroote School of Medicine.

This discovery is a significant advancement towards the development of vaccines for DNA viruses such as herpes and colds, says Lichty.

"We have identified an important step in the detection of DNA viruses by the immune system, and have shown that this is absolutely crucial in the response to a vaccine against these infections. If the key immune system component identified in these studies is not triggered, then vaccination fails."

"So this discovery potentially impacts anyone infected by a virus, receiving a vaccination, fighting cancer or experiencing autoimmunity."

Prior to this study, it was known that interferon regulatory factor-3 (IRF-3), a protein coding gene, contributed to a first line of defense against viral infection by triggering antiviral activity.
https://www.sciencedaily.com/releases/2016/04/160404134036.html Retrieved 2016-04-10