Viral Membrane Channels: Role and Function in the Virus Life Cycle

Sze, Ching Wooen; Tan, Yee-Joo

Viroporins have several known functions at different stages of the viral replication depending on their cellular location during the viral life cycle. While the majority of viroporins play a major role in the final viral release and budding stages, some have been proven to be essential at the early viral genome uncoating and replication steps. Table 1 gives a list of viroporins and their known roles during viral replication determined thus far. Viroporin does not form part of the viral RNA replication complex but is absolutely necessary for the pathogenesis. For instance, the absence of the Vpu viroporin in HIV-1 resulted in the retention of viral particles in the plasma membrane and thus a reduction in infectious viral particle release [63] [64] [65] . In addition, Vpu can also induce the degradation of CD4 at the ER to release the Env glycoprotein from the CD4/Env complex for the production of infectious particles [21, [66] [67] [68] [69] . Lastly, p7 of HCV is required for the production of infectious viral particles in vitro by preventing the acidification of the intracellular membrane vesicles [70] and is absolutely critical for its infection in vivo [71] . Due to their pivotal roles in the viral life cycle, viroporins have become the target of interest in the antiviral therapy with emphasis on HCV p7 and Vpu of HIV-1 [72] [73] [74] [75] [76] . In this review, we highlight the importance of viroporins in the viral life cycle as well as the role they play in cellular immune induction.