3.1. Detection of RVs-D by PAGE and RT-PCR Of a total of 30 pools of fecal samples examined by PAGE, nine
(30%) were positive, displaying typical avian migration patterns (5:2:2:2). These results were consistent with those related to RVs-D (Fig. 1a). The same 30 pools were subjected subsequently to RT-PCR assay to VP6 gene showing that 16 samples (53%) were positive for RVs-D, each generating a fragment of 742 bp as shown in Fig. 1b. The primers used did not yield positive results in nine (control) samples known to be RVs-D negative, although positive for other enteric viruses, such as rotavirus group A (one sample), picobirnavirus (two
samples), reovirus (two samples), rotavirus group A and picobirnavirus (one sample), reovirus and picobirnavirus (three samples). The sensitivity of the method was demonstrated by amplification following serial 10-fold dilutions up to 10−5 with a limit of detection which was equivalent to 5 × 10−4 ng/L (0.5 pg/L) (Fig. 2). The comparison of the results obtained by PAGE (9/30) and RT-PCR (16/30) suggested good reproducibility (kappa = 0.5, p = 0.0004) and in comparing the two techniques, the screening test had a sensitivity of 100% for RT-PCR and the sensitivity of the PAGE was of 56.3%.