PCR-nucleic acid lateral flow immunoassay (NALFIA) with a combination of two primer pairs and one DNA template. The label on the left side of every pair of cartridges is indicating the test line for the existence of Ostrea edulis (FITC OE), Crassostrea gigas (632 CG), and Mytilus edulis (495 ME). The most upper line on the cartridges is indicating the control line of each NALFIA. Primer combinations above the cartridges are indicated with OE, CG, and ME for the primers of O. edulis, C. gigas, and M. edulis, respectively. Part A of the figure shows OE and CG primers in combination with O. edulis DNA (left cartridge), C. gigas DNA (middle cartridge) and a negative control with no DNA template. Part B of the figure shows OE and ME primers in combination with O. edulis DNA (left cartridge), M. edulis DNA (middle cartridge) and a negative control with no DNA template. Part C of the figure shows ME and CG primers in combination with M. edulis DNA (left cartridge), C. gigas DNA (middle cartridge) and a negative control with no DNA template. The image of the 3% agarose gel electrophoresis shows the quality control of the PCR products. The scheme of each gel slots: 1: non-template replicate 1, 2: non-template replicate 2, 3: left cartridge replicate 1, 4: left cartridge replicate 2, 5: middle cartridge replicate 1, 6: middle cartridge replicate 2, M: 50 bp marker, (−): empty.