Investigation into the structural mechanisms underlying functional diversity of interferon-alpha subtypes

Interferons (IFNs) were discovered by Isaacs and Lindeman in 1957, and were found to be the mediators of viral interference; as such they are central to innate immunity. They are expressed robustly upon recognition of viral pathogens, and effect proteomic changes in target cells which establish a virus-restrictive state. IFN-Is include the subtype IFNα, itself a family of 12 proteins in humans. These also play roles in anti-cancer immunity via their anti-proliferative and immune-modulatory effects. IFNα2 and IFNβ have been developed as therapeutics for chronic virus infection and several malignancies, but with limitations due to severe side effects. Here, the functional diversity of the IFNα subtypes was investigated, as a basis for development of further IFNα therapeutics. IFNα14 was a particular focus due to its established high potency across several metrics, and high affinity for the IFN receptor. The viral restriction, anti-proliferative effects, signalling cascades, and proteomic changes effected by IFNα subtypes were compared in order to understand the distinct functional profiles of IFNα subtypes. IFNs’ interactions with their receptor were assessed computationally and biophysically, to identify a structural-functional mechanism explaining their differential effects. These investigations led to the development of a high-throughput IFNAR2 binding screen for synthetic and mutant IFNαs. The higher affinity of IFNα14 was linked to faster intracellular signal generation and increased anti-viral and anti-proliferative efficacy vs other subtypes. Differences between the receptor interactions of each IFN were identified, which may be the basis for different signal propagation across the plasma membrane