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Sunday, February 7, 2010

New broad spectrum antiviral coming soon

Viruses can be very tricky little blighters. Many of them mutate rapidly, keeping one step ahead of their host’s immune system. But thanks to a team of scientists from UCLA, the University of Texas at Galveston, Harvard University, Cornell University and the United States Army Medical Research Institute of Infectious Diseases, there may be hope for defeating some of them.

Viruses come in two broad categories: enveloped and non-enveloped. Enveloped viruses have lipid membranes surrounding their capsids (protein shells). Examples of enveloped viruses include HIV-1, influenza A, and flaviviruses, which are responsible for AIDS, Ebola and Dengue fever respectively. Enveloped viruses rely on their membranes and in particular on the glycoproteins between the lipids for infectivity. Non-enveloped viruses, unsurprisingly, do not have a membrane but consist only of protein shells and nucleic acids. Examples include polyomaviruses (which can cause cancer), adenoviruses (assorted respiratory and gastrointestinal diseases) and picornoviruses such as poliovirus.

Left: diagram of enveloped virus (HIV-1);

Right: schematic of naked capsid (adenovirus)

Benhur Lee and his colleagues spent four years searching for and testing drugs before discovering the compound they named LJ001. After testing it on 23 pathogens, some of them, like Ebola, requiring maximum-containment biosafety facilities, they discovered that LJ001 only affected the enveloped viruses.

Although the exact mechanism of action is not yet known, the scientists believe that LJ001 damages both viral and cellular membranes. Unlike viruses, cells have mechanisms for repairing their membranes. Preliminary tests show no toxicity at effective antiviral concentrations. In contrast, the viruses are inactivated once their envelopes are disrupted.

If further tests bear out preliminary results, LJ001 could prove to be an effective treatment for most if not all enveloped viruses.