Representational differential analysis detects amplification of satellite sequences in postweaning multisystemic...

Representational difference analysis (RDA) was used as a molecular approach to identify unique sequences associated with postweaning multisystemic wasting syndrome (PMWS) in pigs. Three rounds of subtractive hybridization and amplification between driver DNA extracted from normal pigs and tester DNA from PMWS-affected animals were performed. The final product corresponding to sequences associated with PMWS in pigs was analyzed using agarose gel electrophoresis, and 9 fragments were visualized after staining with ethidium bromide. Eight recombinants were successively cloned and sequenced, and the results were then compared with existing databases. Most of the PMWS clones isolated were satellite sequences from pig centrometric regions and 1 was a microsatellite sequence. One clone represented a microsatellite sequence, and 2 clones showed no homology with any gene found in the databases. The sequence comparison data did not reveal any homology with an infectious agent such as a virus or a bacterium. In the present experimental setting, it was concluded that PMWS in pigs triggers molecular changes such as an amplification of genomic regions containing repeated sequences.