Interferon helps cells help themselves.

Interferon helps cells help themselves

The natural chemical interferon has engendered high expectations for therapeutic applications, including protection against the common cold (SN: 1/11/86, p. 20), but little is known about ow it acts. Charles Weissmann at the University of Zurich in Switzerland and his colleagues are examining the means by which interferon, naturally produced in response to a viral infection, makes cells resistant to further attack.

Interferon triggers production of at least 10 cellular proteins, only some of which have been identified so far, Weissmann reports. But when interferon protects mouse cells against the influenza virus, only one protein is required. "This is the first identification of a single protein [that confers] resistance to a specific virus," Weissmann says.

Some mouse strains are sensitive to influenza virus, while others are naturally resistant. But even the resistant mice are killed by influenza virus after they are treated with antibody against interferon. The scientists have identified the gene that is turned on by interferon and that differs in the influenza-resistant and -susceptible mice. In the susceptible animals the gene, called Mx, makes a truncated version of its normal product. With recombinant DNA techniques, the scientists have transferred many copies of a normal Mx gene into cells of susceptible animals. These cells then resist influenza, but not other viral infections. In fact, the cells do not even need interferon to induce the resistance. Weissmann suggests Mx function may reflect a peculiarity of influenza virus infection, its stealing of a piece of host messenger RNA. "My guess is that this [single protein resistance] is not often the case," he says.