<prompt> Which pa of bacteria is most antigenic -Proetin coatLipopolysaccharideNucleic acidLipids  <response>: Antigens are usually proteins and polysaccharides, and less frequently, lipids. This includes pas coats, capsules, cell walls, flagella, fimbrae, and toxins of bacteria, viruses, and other microorganisms. Lipids and nucleic acids are antigenic only when combined with proteins and polysaccharides. Ref: Ananthanarayan Panikers textbook of microbiology 9th edition pg:88 