Essential Function of the Pseudorabies Virus UL36 Gene Product Is Independent of Its Interaction with the UL37 Protein

Abstract

) but in contrast to PrV-⌬UL36F, PrV-UL36BSF was able to replicate in rabbit kidney (RK13) cells, although maximum virus titers were reduced ca. 50-fold and plaque diameters were reduced by ca. 45% compared to wild-type PrV. PrV-⌬UL36F was able to productively replicate after repair of the deleted gene or in a trans-complementing cell line. Electron microscopy of infected RK13 cells revealed that PrV-UL36BSF and phenotypically complemented PrV-⌬UL36F were capable of nucleocapsid formation and egress from the nucleus by primary envelopment and deenvelopment at the nuclear membrane. However, reenvelopment of nucleocapsids in the cytoplasm was blocked. Only virus-like particles without capsids were released efficiently from cells. Interestingly, cytoplasmic nucleocapsids of PrV-UL36BSF but not of PrV-⌬UL36F were found in large ordered structures similar to those which had previously been observed with PrV-⌬UL37. In summary, our results demonstrate that the interaction between the UL36 and UL37 proteins is important but not strictly essential for the formation of secondary enveloped, infectious PrV particles. Furthermore, UL36 possesses an essential function during virus replication which is independent of its ability to bind the UL37 protein.

Determination of Interactions between Tegument Proteins of Herpes Simplex Virus Type 1

“…UL37 then interacts with VP5-bound UL36 to complete the inner tegument layer (20). In the case of PRV, a recent study shows that deletion of the UL37 binding site in UL36 does not abolish secondary envelopment (14). This suggests that the interaction, though important, is not essential for virion assembly.…”

Dynamic ubiquitination drives herpesvirus neuroinvasion

“…Upon virus entry into a cell, pUL36 becomes exposed to the cytosol (4,13,14) and directs delivery of the capsid and its DNA content to the nucleus (2,(15)(16)(17)(18)(19). Following replication, pUL36 is also essential for viral assembly and egress (20)(21)(22).…”

Cell biological and molecular characteristics of pseudorabies virus infections in cell cultures and in pigs with emphasis on the respiratory tract

“…The cytoskeletal structures and motor proteins necessary for the transport to this site are not characterized yet. It is very well possible that tegument proteins encoded by US3, UL36 and UL37 which are found on the outside of cytoplasmic nucleocapsids, are involved in this migration with p(UL36) physically interacting with p(UL37) [16,27]. The envelope glycoproteins are anchored in the membranes of TGN vesicles, presenting their cytoplasmic tails in the cytosol.…”