Contributed by Guest Blogger: M. Steinschneider ’14
The influenza virus’s unique, 8 fragments genomic structure makes the virus quite fast to evolve, and therefore very difficult to vaccinate against. New techniques for protection against the virus are thus desirable. A 2008 study by Dimmock et. al has identified a naturally existing sequence of defective influenza A RNA, named 244 RNA. Their study suggests that defective, 244 RNA viruses protect against H1N1, as well as other strains of the influenza A virus. This holds interesting implications for the prevention and treatment of influenza, perhaps providing an alternative to vaccination.
Experiments conducted in the study support Dommick’s conclusion that the 244 RNA virus protects against functional strains of influenza A. For instance, a group infected with the 244 RNA carrying virus was then infected with a human H3N2 strain, and then compared to a control group that was infected with the same H3N2, but not given the protecting virus. While the control group lost weight and demonstrated other signs of illness, the group given the protecting virus remained healthy.
The mechanism suggested by Dimmock et. al is that the 244 RNA protecting virus infects cells in the respiratory tract, an important target for the influenza Virus. Since influenza A viruses infecting the same cell are capable of swapping genetic information, due to their unique genomic arrangement, other influenza viruses introduced into the host will take on the defective RNA. The packaging process does not favor the functioning RNA sequence over the defective 244 RNA, so the 244 RNA is favored if it proportionally outweighs the functional RNA sequence.
Although this seems highly promising for fighting influenza, it does lead to several questions. For instance, is it possible that the protecting virus could mutate at some point? If this were to happen, it may cease to be benign. There is also the chance that Influenza A may mutate to have a mechanism for favoring the correct RNA during genetic swapping. Still, 244 RNA seems to be an effective and creative approach to protecting against influenza, by turning the virus’s strength (genetic flexibility in multi-infected cells) against it.