LA JOLLA, CA January 20, 2011 Scientists at The Scripps Research Institute have found that a known enzyme in cells protects against measles virus, likely by altering the virus's genetic material, RNA. Cells lacking the enzyme become highly vulnerable to the virus's destructive effects. The enzyme also protects against several other respiratory viruses, including influenza A.
"We believe that host cells use this RNA-editing enzyme to slow these viruses' ability to replicate," said Michael B. A. Oldstone, the study's senior author and a professor at Scripps Research's La Jolla, California campus. The study's first authors are Simone V. Ward, a senior research associate in the Scripps Research Oldstone laboratory, and Cyril X. George of the University of California, Santa Barbara.
The finding represents a significant improvement in the understanding of measles infections, which still kill about 150,000 children and adults around the world every year. The paper, which was published recently in Proceedings of the National Academy of Sciences, has prompted commentaries in the journals Nature Reviews Microbiology and Viruses.
The focus of the study was the enzyme ADAR1 ("adenosine deaminase acting on RNA, 1"), which is known to be produced in high amounts in measles-infected cells. ADAR1 has been suspected as a "restriction factor" that inhibits viral replication.
ADAR1's role against measles has been difficult to nail down, however. In mice genetically engineered to be infectable by measles a virus that normally infects only humans ADAR1 is required for embryonic development, as in all mice. Thus the standard "gene knockout" technique, which would enable scientists to see how measles infections proceed without ADAR1, hasn't been feasible.
In this study, Ward, George, and Oldstone, and their colleagues knocked out only one of the two forms of ADAR1 produced in cells. This form, p150, is the one pro
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Scripps Research Institute