Abstract: Disclosed are a method for testing for the presence of a cytomegalovirus antigen by using an antibody which specifically recognizes cytomegalovirus Lower matrix protein pp65, as a primary antibody, which comprises using an alkaline phosphatase-labeled antibody as a secondary antibody and a method for testing for the presence of a cytomegalovirus antigen which comprises using an alkaline phosphatase-labeled antibody which specifically recognizes cytomegalovirus Lower matrix protein pp65, or (Fab').sub.2 or Fab' fragment of the antibody which specifically recognizes cytomegalovirus Lower matrix protein pp65 as a primary antibody.

Abstract: There are disclosed a hybridoma obtained by fusing a myeloma cell with an anti-thymosin .alpha.1 antibody-producing cell and selecting a hybridoma which produces a monoclonal antibody that recognizes the N-terminus of thymosin .alpha.1; an anti-thymosin .alpha.1 monoclonal antibody which is produced by the hybridoma, and a method for measuring thymosin .alpha.1 which comprises forming a three-component complex comprising thymosin .alpha.1, the anti-thymosin .alpha.1 monoclonal antibody (A), and an anti-thymosin .alpha.1 antibody (B) that recognizes a different site of thymosin .alpha.1 than antibody (A) does; forming a four-component complex of said three- component complex with a labeled substance (C) that specifically binds to antibody (A) or antibody (B) of the three-component complex; and detecting the labeled substance in said four-component complex.