By combining the advantages of RT-PCR with the sensitivity of bioluminescence using the photoprotein aequorin, a bioluminescence assay has been applied to the determination of message regulation during infectious disease. The bioluminescence produced by the aequorin conjugate covers more than seven logs concentration, of which approximately five logs produces a linear relationship between product and bioluminescence signal. Aequorin - based bioluminescent detection protocols for mRNA are sensitive into the attomolar range, which obligate fewer cycles of PCR and avoid the plateau effect traditionally associated with other noncompetitive RT-PCR techniques. Additional advantages of aequorin-based bioluminescence methods are ease of automation, compatibility with microtiter plate format, low cost, and flexibility.