The second enzyme, ribonuclease H (RNAseH) had eluded investigators in the lab. With no means to measure it, researchers hit dead ends even though they believed the enzyme was a promising target, in theory.
So, with five approved drugs targeting the first enzyme and none aimed at the second, Tavis sparred with RNAseH for nearly two decades.
Search for an Assay
Tavis was searching for a yardstick, of sorts.
Though it made sense to target RNAseH, no method existed that allowed researchers to measure the enzyme's activity. Tavis was looking for an assay, a way to tell if a substance would block the enyzme's function.
After years of work, Tavis and his research team saw the first glimmer of activity and were able to develop an assay for RNAseH, allowing him to begin to study the enzyme and try out promising theories about how to block it.
Borrowing from HIV
Because the hepatitis B and HIV viruses both use reverse transcription, the mechanism by which they copy themselves in the body's cells, hepatitis B researchers have been able to benefit from advances in HIV research. Thanks to substantial funding, HIV research has made rapid progress since the virus's discovery. Several effective drugs for HIV treatment work by targeting the reverse transcription process also work against hepatitis B virus.
Though the viruses are quite different, Tavis and his colleagues Stefan Sarafianos, Ph.D. at the University of Missouri and Michael Parniak, Ph.D., at the University of Pittsberg believed that the shared process suggested there should be some chemical similarities that could be exploited.
"Just as every car has tires and an engine, both of these viruses have pieces that serve similar functions. You can take an engine from one car and try it in the other. It might not be a perfect
|Contact: Carrie Bebermeyer|
Saint Louis University