Isolation of T-Cell Antigens by Using a Recombinant Protein Library and Its Application to the Identification of Novel Vaccine Candidates against Schistosomiasis

Abstract

ABSTRACT We present here a novel approach to identify T-cell antigens from any infectious agent by use of a library of purified recombinant proteins. Essential features of this strategy include (i) a highly efficient cDNA cloning system which negatively selects against nonrecombinant transformants by making use of the bacterial Eco K restriction system, (ii) affinity staining of cDNA clones expressing recombinant proteins, and (iii) a procedure of simultaneous purification of recombinant proteins from large numbers of isolated clones (representing the protein library) in a single step from pools consisting of up to 24 individual clones. The feasibility of the screening system was confirmed by constructing a protein library of the human parasite Schistosoma mansoni . The recombinant antigens of this library were used to stimulate CD4 + T cells derived from the axillary lymph nodes of mice vaccinated with irradiated cercariae. In initial screening experiments, we detected parasite-specific proliferation and gamma interferon (IFN-γ) secretion in response to several pools of cDNA clones. Further analysis of one particular pool revealed that only one of its constituents stimulated considerable IFN-γ secretion by CD4 + T cells and that the expressed antigen is identical to a small fragment of myosin heavy chain.