| abstract |
Multiple copy epitope immunoassays are produced by: (1) identifying nucleotide sequences that encode a plurality of different epitopes; (2) placing the nucleotide sequences into an expression cassette wherein at least two copies of a sequence coding for the same epitope, preferably from different strains of a pathogen, are placed in the cassette; (3) transforming a suitable host with the cassette in order to express the sequences encoding the epitopes; (4) purifying the expressed epitopes; and (5) coating the epitopes on a surface of a substrate. The purified epitopes are encompassed by the general structural formula (A)x-(B)y-(C)z which represents a linear amino acid sequence, B is an amino acid sequence of an epitope or cluster of epitopes and each B contains at least five and not more than 1,000 amino acids, y is an integer of 2 or more, A and C are each independently an amino acid sequence of an epitope or cluster of epitopes not adjacent to B in nature and x and z are each independently an integer of 0 or more wherein at least one of x and z is 1 or more. The epitopes of the invention are more soluble than and are therefore more easily purified than conventional epitopes. Further, the presence of repeating epitope sequences (repeating at least B in the same linear amino acid sequence from different strains of a pathogen) increases the sensitivity and specificity of the assay. Repeated epitope sequences in a single linear antigen also decreases masking problems and makes it possible to include a greater number of epitopes on a unit area of substrate thereby improving sensitivity in the detection of antibodies. |