The compound may prove to be more effective than any other drug on the market
SFU virologist Masahiro Niikura and PhD student Nicole Bance have collaborated with researchers from Australia, the United Kingdom, and local institutions to test the flu-con-trolling capacity of a new anti- influenza drug.
The team is headed by enzymologists and chemists at UBC who first synthesized the new compound. Positive results were achieved from test tube ex- periments and as a result, Bance and Niikura ran a series of ani- mal model tests which also pro- duced very promising results.
“We gave mice this new drug and then infected them with influenza to see if they were protected against the virus. All of them survived, which was good,” said Bance. The group’s research will be published in the journal Science, and it became available online in Sci- ence Express in late February.
In order to increase the number of infected cells in an organism, the influenza virus must leave an infected cell to attack healthy cells. A viral enzyme or a large molecule that speeds up chemical reac- tions and helps specific units bind-called nuramidase helps influenza escape the cell by processing sialic acid, a sim- ple sugar on the cell surface. If another substance tightly binds to nuramidase, the virus cannot exit infected cells because the enzyme can no longer digest the acid.
The new drug is designed to form an almost irreversible covalent bond to nuramidase in order to block it from bonding to sialic acid. Because the new compound is more structurally similar to sialic acid than other nuramidase inhibitor drugs, it will be less prone to generating resistant influenza strains and an ideal choice for future anti- influenza drugs.
The compound carries the advantages of two exist- ing nuramidase inhibitors on the market: Tamiflu and Relenza. Tamiflu is popular with physicians because it is water-soluble and available orally, but overuse has promoted the emergence of Tamiflu-resistant influenza strains.
In contrast, Relenza is effective against most Tamiflu-resis- tant viruses and administered through a nasal spray. “The new compound combines the ad- vantages of Relenza with Tami-flu, so it will be orally available and effective against Tamiflu resistant strains,” said Bance.
Ultimately, anti-influenza drugs like the one tested by Nii- kura and Bance buy more time for vaccine production. Because clinically isolated viruses quickly kill the embryonated chicken eggs they are produced in, weakened viruses must be created in order to produce high amounts of viruses ready for vaccines. This process can take a month or longer, accord- ing to Niikura.
Anti-influenza drugs directly alter the activities of nuramidase, making them effective against both old and new influenza strains unlike vaccines. “Because the required muta- tions are different, anti-viral drugs and vaccines can compliment each other.” said Bance. “This could be effective when used with currrent drugs to re- duce the impact of a pandemic caused by emerging strains.”
