The whole encoding sequence for Yersinia pestis LcrV antigen was cloned into pET-32a(+) and expressed in Escherichia Coli BL21 (DE3). The LcrV was high level expressed in the E coli cytoplasm in a completely soluble form. Recombinant LcrV could be purified from the supernatant of the bacteria lysate after chromatography using a combination of Phenyl-Sepharose F F, DEAE-Sepharose F F and Hiload (TM) Superdex (TM) 75. The final yield of approximately 3 g of purified rLcrV from 42 L bioreactor containing 25 L LB medium was obtained. High-titer IgG directed against rLcrV was detected positive after immunization on the BALB/c mice. The results presented here exhibit the ability to generate multi-gram quantities of non-tagged rLcrV from E. coli that can be used for the development of vaccine for preventing plague. (C) 2007 Elsevier Inc. All rights reserved.