<prompt> In pontaic fever, which antigen is seen in urine?Lipopolysaccharide-1Lipopolysaccharide-2Lipopolysaccharide-4Lipopolysaccharide-6  <response>: Ans. is a i.e., Lipopolysaccharide-1 Legionella are classified into serogroup on the basis ofgroup specific lipopolysaccharide somatic antigen or O antigen. Legionella pneumophila sero-group-1 LP-1 is the most common infecting organism. Urine test detect LP-1. 