Discovery of a New Mammalian Antiviral Response
Specific proteins within infected cells trigger an innate immune response known as the interferon response. As a result, neighboring cells are activated, which can cause the primarily infected cell to die. Invertebrates also have a mechanism involved in the immune response, called the RNA interference pathway, or RNAi. The RNAi is triggered by a RNA molecule which arises during the copying of the viral genome.
A science article featured in Science News Daily explains how, although RNAi has long been known to be present in mammals, the belief was that it was used for gene regulation and did not play a role in viral immunity. Evidence now exists that the mammalian RNAi does, in fact, take part in the immune response.
Why has the role of RNAi in the immunity of mammals failed to be recognized for so long? One reason given by researchers are the counter-defenses in plants and invertebrates that were developed in response to RNAi in order to inhibit the machinery of infected cells, causing the presence of antiviral RNAi to be hidden. Also, researchers have looked at differentiated cells where the interferon response is almost entirely responsible for providing an immune response.
In spite of its having gone undetected for so long, researchers claim that the beauty of the system they have discovered is its simplicity. The virus determines the specificity of the response so that the potential to adapt to a variety of viruses is indicated.