Fowlpox virus encodes two p28-like ubiquitin ligases that are expressed early and late during infection

Many cellular processes are regulated by the ubiquitin-proteasome system. Therefore, it is not surprising that viruses have adapted ways to manipulate the ubiquitin-proteasome system to their own advantage. p28 is a poxvirus encoded ubiquitin ligase that contains an N-terminal KilA-N DNA binding domain and a C-terminal RING domain required for ubiquitin ligase activity. p28 is encoded by a wide range of poxviruses, including members of the Avipoxviruses. Here we show that fowlpox virus (FWPV) and canarypox virus (CNPV) each contain two distinct p28-like ubiquitin ligases; an observation not seen in other members of the poxvirus family. FWPV150 and FWPV157 are both ubiquitinated during infection and co-localize with conjugated ubiquitin at the viral factory. Interestingly, we demonstrate that FWPV150 was actively transcribed early, while FWPV157 was expressed late. Overall, these observations suggest different temporal roles for FWPV150 and FWPV157, an observation unique to the Avipoxviruses.