The protection againts small pox by previous infection with cowpox represents -: (A) Antigenic cross-reactivity, (B) Antigenic specificity, (C) Passive immunity, (D) Innate immunity
Answer is A. Cross-reactivity applies to the reaction between two different species as opposed to the self-reactivity.In immunology, the cross-reactivity has a more narrow meaning of the reaction between an antibody and an antigen that differs from the immunogen.