Neisseria gonorrhoeae and Neisseria meningitides are pathogenic, obligate, gram-negative bacteria responsible for a variety of diseases including meningococcal meningitis and gonorrhea. Subsequent to pili binding, opacity associated (Opa) proteins bind to host plasma membrane receptors and signal the loss of the pili and host actin reorganization, which facilitates endocytosis into the host cytoplasm. Different Opa proteins bind to various host receptors and are classified into two classes. The larger class, OpaCEA, bind to carcinoembryonic antigen-like cellular adhesion molecules (CEACAMs), and the smaller class, OpaHS, bind to  heparansulfate proteoglycan receptors (HSPGs).