Involvement of the African swine fever virus protein pH108R in virion morphogenesis

African swine fever virus (ASFV) is the causative agent of the highly contagious and devastating haemorrhagic swine disease for which there are no effective vaccines or treatments available. The ASFV infectious cycle initiates with the viral absorption and entry into the host cell, then ASFV undergoes the uncoating process, viral inner envelope and endosome membrane fusion, DNA replication and gene transcription as well as translation, subsequently ASFV morphogenesis takes place within viral factories. ASFV morphogenesis is highly complex, and the mechanisms involved in ASFV morphogenesis are not well understood at present. Here, we reported that the inner envelope protein pH108R is involved in the ASFV morphogenesis. Interestingly, the absence of pH108R results in the formation of large numbers of tubular structures and bilobulate structures, providing evidence that pH108R plays a role in ASFV morphogenesis. Furthermore, the absence of pH108R inhibits the proteolytic processing of core-shell polyproteins pp220 and pp62. pH108R is identified as associated with capsid proteins p49 and p72, displaying the function of pH108R in the assembly of the capsid. Besides, the absence of pH108R reduces the protein levels of pA104R. Additionally, the pathogenicity of the pH108R-deleted ASFV strain is attenuated in pigs compared with the parental virus. These findings elucidate the regulatory role of pH108R in ASFV morphogenesis and provide an attractive target for vaccine development.