Effect of 50 Kilobase-Plasmid, pKDSC50, of Salmonella choleraesuis RF-1 Strain on Pig Septicemia

Abstract

Salmonella choleraesuis strains with and without 50-kilobase plasmid (pKDSC50) were intravenously inoculated into Yorkshire pigs. By the inoculation of 7.2×10⁵ -3.5×10⁷ cells, RF-1 strain with pKDSC50, but not 31N-1 strain without the plasmid, caused a septicemia. The inoculation of 8.7×10⁹ RF-1 cells killed pigs at 2-4 day postinfection with severe hemorrhage on the whole body. Pigs with a similar number of 31N-1 cells (8.3×10⁹ cells), showed milder hemorrhage, and they died at 6 day postinfection. These results indicated that pKDSC50 is reduired for RF-1 strain to express the full virulence causing a heavy cutaneous pig septicemia.