Virulence of gonococci is due to

Pili: hair like structures several micrometers long. Acts as a virulence factor by promoting attachment to host cells and inhibiting phagocytosis. Pili are composed of repeating peptide subunits consisting of conserved and variable regions. Pili undergo antigenic and phase variations. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 234