Analysis of the subcellular trafficking properties of murine cytomegalovirus M78, a 7 transmembrane receptor homologue

• Published in: Journal of general virology 2009-01, Vol.90 (1), p.59-68
• Main Authors: Sharp, E. L, Davis-Poynter, N. J, Farrell, H. E
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cell Line; Cells, Cultured; Cricetinae; Dimerization; Endocytosis; Fundamental and applied biological sciences. Psychology; Humans; Membrane Proteins - metabolism; Mice; Microbiology; Miscellaneous; Murine cytomegalovirus; Muromegalovirus - physiology; Protein Transport; Rat cytomegalovirus; Viral Proteins - metabolism; Virology
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.004853-0

1 Infectious Diseases, Animal Health Trust, Newmarket, Suffolk CB8 7UU, UK 2 The University of Queensland, Clinical Medical Virology Centre and Royal Children's Hospital, Sir Albert Sakzewski Virus Research Centre, QLD 4072, Australia Correspondence H. E. Farrell h.farrell1{at}uq.edu.au Murine cytomegalovirus (MCMV) M78 is a member of the betaherpesvirus ‘UL78 family’ of seven transmembrane receptor (7TMR) genes. Previous studies of M78 and its counterpart in rat cytomegalovirus (RCMV) have suggested that these genes are required for efficient cell–cell spread of their respective viruses in tissue culture and demonstrated that gene knockout viruses are significantly attenuated for replication in vivo . However, in comparison with other CMV 7TMRs, relatively little is known about the basic biochemical properties and subcellular trafficking of the UL78 family members. We have characterized MCMV M78 in both transiently transfected and MCMV-infected cells to determine whether M78 exhibits features in common with cellular 7TMR. We obtained preliminary evidence that M78 formed dimers, a property that has been reported for several cellular 7TMR. M78 traffics to the cell surface, but was rapidly and constitutively endocytosed. Antibody feeding experiments demonstrated co-localization of M78 with markers for both the clathrin-dependent and lipid raft/caveolae-mediated internalization pathways. In MCMV-infected cells, the subcellular localization of M78 was modified during the course of infection, which may be related to the incorporation of M78 into the virion envelope during the course of virion maturation.