Consequently, less reactogenic acellular pertussis combination vaccines were developed (DTaP), comprised of 1–5 purified pertussis antigens (DTaP), i.e. pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (Prn) and fimbriae (Fim2 and Fim3). The gene discussed is CIAO3; the disease is pertussis.