Advantages of the System
The advantages of the Q-Plex ELISA include time, sample, and cost savings. Multiplex ELISA is an evolutionary step from a traditional ELISA involving similar steps of antigen/sample incubation, secondary or detection antibody incubation, IR fluorescent or chemiluminescent label incubation, wash steps, and plate reading resulting in a 2.5 hour assay time.
Nonsandwich ELISAs such as competitive (a single capture antibody is placed on the plate and a labeled antigen is used that competes with the antigen in the sample for binding with the antibody) or direct ELISAs (the antigen is on the plate rather than a capture antibody) have been designed and multiplexed that require as little as 30 minutes total assay time.
When the time it takes to run a single multiplex ELISA is compared to the time required by multiple standard ELISAs, the time savings is apparent. Similar logic applies to sample volumes. Running 16 simultaneous ELISAs in a single well (the sample amount required for a Q-Plex ELISA is 30 µL per well) greatly reduces the amount of sample required to obtain the same results.
While multiplexing technologies for protein detection are useful for screening which proteins are in a specific sample, a less obvious but potentially more significant use is for the establishment of protein-expression patterns. Such patterns might eventually lead to the discovery of better biomarkers, especially in circumstances where a single suitable biomarker has yet to be found.
For example, cytokines are generally low-level transitory signaling molecules that are tightly regulated. However, they are differentially upregulated and released depending upon the stimulus. Using a mouse cytokine Q-Plex ELISA measuring 16 different cytokines and chemotactic factors researchers have found that influenza virus stimulates a rather consistent pattern of cytokine release in mice.
The major upregulation of RANTES, interleukins 1α, 6, 12, and monocyte chemotactic protein-1 in mice following influenza virus infection is shown in the Figure, with lesser alterations in the other proteins detectable by the array. While this is far from sufficient for diagnostic purposes it does demonstrate that protein-expression patterns are elicited from a virus, and that even patterns of low-abundance transitory proteins are detectable.