(A) Nested PCR-EIA analysis on a tenfold serial dilution of
strain 92/1293. (B) Visualisation of the tenfold serial dilution on a 1.2% agarose gel following nested PCR. 103 IFU (lane 1) until 10-2 IFU (lane 6). Lane 7 shows the PCR results on a negative control. Lane 8: Phage lambda PstI fragments as size marker.