UniVec is a database that can be used to quickly identify segments within nucleic acid sequences which may be of vector origin (vector contamination). Screening using UniVec is efficient because a large number of redundant sub-sequences have been eliminated to create a database that contains only one copy of every unique sequence segment from a large number of vectors.
http://www.ncbi.nlm.nih.gov/VecScreen/UniVec.html

Characterization and classification of nucleic acid vectors.
http://genome-www.stanford.edu/vectordb/