Zika virus utilises the ubiquitin-proteasome pathway during infection of mosquito and human cells

Arthropod-borne viruses are able to infect vertebrate and invertebrate hosts. One such arbovirus is Zika virus (family Flaviviridae) that is mainly transmitted to humans by Aedes mosquitoes causing febrile illness and congenital Zika syndrome in infants. An interplay between host and virus proteins enables ZIKV to manipulate its host's cellular machineries in order to facilitate infection and evade antiviral responses. A possible mechanism it utilises is the ubiquitin-proteasome pathway (UPP) where target proteins are ubiquitinated and subsequently degraded by the proteasome. Results of proteomics analysis of Ae. aegypti cell lines (AF5) stably expressing V5-tagged ZIKV capsid (C), anchored capsid (AC) or non-structural 3 (NS3) proteins revealed that these viral proteins interact with effector proteins of the UPP. One of these proteins is TER94 an AAA-ATPase that acts as a chaperone segregating ubiquitinated proteins to the proteasome complex. Knockdown experiments of TER94 or its human ortholog VCP using dsRNA or siRNAs showed reduced virus replication in AF5 or A549 cells. Using small molecule inhibitors of UPP proteins also diminished ZIKV replication. Inhibiting different stages of the pathway have identified critical steps during early stages of infection. The ubiquitination of lysine-rich ZIKV C and its interaction with TER94/VCP could be one of the many universal strategies that the virus employs when it switches between mosquito and human hosts. Understanding how ZIKV is able to infect both human and insect species could provide novel strategies for prevention and therapeutics.

Keywords: Zika virus, Aedes aegypti, ubiquitin-proteasome pathway, mosquito, virus-host interaction