The present application provides methods and uses of O-oligosaccharyltransferase (O-OTases) for generating vaccines. In particular, the present application provides a method of synthesizing a glycoprotein comprising glycosylation of pilin-like protein ComP using a PglLComP O-OTase. Uses of glycoproteins synthesized by glycosylating ComP using PglLComP O-OTase, particularly for the preparation of vaccines and the like, including a vaccine to Streptococcus, is also provided.
