The pUL47 tegument protein of Marek’s Disease Virus interacts with p32/C1QBP to promote horizontal transmission

Inter-individual transmission is an essential part of viruses’ life cycle, yet the molecular basis of transmission remains elusive. Using Marek’s Disease Virus (MDV), a deadly and contagious herpesvirus of chickens that is transmitted by inhalation of contaminated dander, we previously demonstrated that tegument protein pUL47 was necessary for horizontal transmission in the natural host while being dispensable for pathogenesis and replication. We showed that pUL47 was also necessary for the correct splicing and expression of UL44 transcripts, which encode glycoprotein gC, another viral protein known as essential for MDV’s transmission. Here, with the aim of characterizing the molecular basis for the role of pUL47 in transmission, we identify the cellular protein p32/C1QBP / gC1qR, a regulator of mRNA splicing, as a binding partner. We demonstrate that this interaction is necessary for transmission while being dispensable for the correct splicing and expression of UL44 transcripts, thus uncoupling the role of pUL47 in transmission from gC. These results provide a deeper molecular understanding of the natural transmission of a Herpesvirus.