General Information: Specific virulence factors are encoded within pathogenicity islands (PAIs) that are required for the invasive phenotype associated with Yersinia infections. One key virulence plasmid contained by the three human-specific pathogens is pCD1/pYv, which encodes a type III secretion system for the delivery of virulence proteins that contribute to internalization into the host cell. This species is a food and waterborn pathogen that causes gastroenteritis (inflammation of the mucous membranes of the stomach and intestine) and is able to proliferate at temperatures as low as 4 degrees C.