The Role of Phosphoinositide 3-Kinase-Akt Signaling in Virus Infection

Successful virus infection of host cells requires efficient viral replication, production of virus progeny and spread of newly synthesized virus particles. This success, however also depends on the evasion of a multitude of antiviral signaling mechanisms. Many viruses are capable of averting antiviral signals through modulation of host cell signaling pathways. Apoptotic inhibition, for example, is a universal intracellular antiviral response, which prolongs cellular survival and allows viruses to complete their life cycle. Ongoing apoptotic inhibition contributes to the establishment of latent and chronic infections, and has been implicated in viral oncogenesis. The phosphoinositide 3-kinase (PI3K)-Akt pathway has become recognized as being pivotal to the inhibition of apoptosis and cellular survival. Thus, modulation of this pathway provides viruses with a mechanism whereby they can increase their survival, in addition to other established mechanisms such as expression of viral onco-genes and direct inhibition of proapoptotic proteins. Recent research has revealed that this pathway is up-regulated by a number of viruses during both short-term acute infections and long-term latent or chronic infections. During acute infections PI3K-Akt signaling helps to create an environment favorable for virus replication and virion assembly. In the case of long-term infections, modulation of PI3K-Akt signaling by specific viral products is believed to help create a favorable environment for virus persistence, and contribute to virus-mediated cellular transformation.