The rectal route of immunization has also shown promising results against enteric pathogens by inducing appropriate immune effectors in the intestinal mucosa [102–105] Intrarectal immunization with recombinant vaccinia virus expressing carcinoembryonic antigen (CEA) has shown promising results in preventing the progression towards invasive colorectal cancer and inducing CEA-specific local mucosal and systemic humoral and cell-mediated immunity [106]. The gene discussed is CEACAM5; the disease is colorectal cancer.