Method to treat disease using a nucleic acid vector encoding a highly compact multi-input logic gate

A contiguous polynucleic acid molecule encoding a classifier gene circuit comprising at least two cassettes, wherein each cassette comprises a regulatory component and a response component, wherein:

• (i) at least one cassette comprises:
• a 5′ regulatory component comprising a transactivator response element, a transcription factor response element and a minimal promoter, and a 3′ response component comprising a sequence encoding an output;
• and
• (ii) at least one cassette comprises:
• a 5′ regulatory component and a 3′ response component comprising a nucleic acid sequence encoding a transactivator protein, wherein the transactivator of (ii), when expressed as a protein, binds and transactivates the transactivator response element of (i), and wherein the 5′ regulatory component of cassette (ii) comprises a transcription factor response element,
• wherein the expression of the output driven by either a transcription factor binding to the transcription factor response element of cassette (i) alone, or by the transactivator protein bound to the transactivator response element of cassette (i) alone, is less than the expression of the output in the presence of both said transcription factor and said transactivator protein,
• wherein the at least one cassette of (i) and the at least one cassette of (ii) are in a divergent orientation,
• wherein the 3′ response component of the at least one cassette of (i) and/or the at least one cassette of (ii) comprises at least one microRNA target site,
• and wherein the transcription factor response elements in (i) and (ii), and the microRNA target site, are sensors of inputs of the classifier gene circuit that controls the expression of the output.