CD8A and infection: Two A10 homozygous animals (403992 and 302186), previously immunized by the ‘infection and treatment method’ vaccination protocol, were challenged with a lethal dose of T. parva sporozoites and the CD8 T‐cell responses against Tp249–59, Tp250–59 and Tp298–106 were monitored directly ex vivo using tetramers (Fig. 6a,b).