Construction of Lactococcus lactis expressing secreted and anchored Eimeria tenella 3-1E protein and comparison of protective immunity against homologous challenge

Two novel plasmids pTX8048-SP-Delta 3-1E and pTX8048-SP-NA Delta 3-1E-CWA were constructed. The plasmids were respectively electrotransformed into L lactis NZ9000 to generate strain of L lactis/pTX8048-SP-Delta 3-1E in which 3-1E protein was expressed in secretion, and L lactis/pTX8048-SP-NA Delta 3-1E-CWA on which 3-1E protein was covalently anchored to the surface of bacteria cells. The expression of target proteins were examined by Western blot. The live lactococci expressing secreted 3-1E protein, anchored 3-1E protein, and cytoplasmic 3-1E protein was administered orally to chickens respectively, and the protective immunity and efficacy were compared by animal experiment. The results showed oral immunization to chickens with recombinant lactococci expressing anchored 3-1E protein elicited high 3-1E-specific serum IgG, increased high proportion of CD4(+) and CD8 alpha(+) cells in spleen, alleviated average lesion score in cecum, decreased the oocyst output per chicken compared to lactococci expressing cytoplasmic or secreted 3-1E protein. Taken together, these findings indicated the surface anchored Eimeria protein displayed by L lacits can induce protective immunity and partial protection against homologous infection. (C) 2017 Elsevier Inc. All rights reserved.