The dengue virus M protein localises to the endoplasmic reticulum and forms oligomers

The dengue virus membrane (M) protein is a key component of the mature virion. Here, we characterised the cellular behaviour of M using a recombinant protein construct to understand its inherent properties. Using confocal microscopy, we showed that M and its intracellular precursor, prM, localised to the endoplasmic reticulum. M protein was also detected on the cell surface and secreted, suggesting that M can enter the secretory pathway. In addition, cross-linking studies showed that M can form dimers and tetramers. These findings suggest that M behaves as a secretory protein analogous to the major envelope protein E.