To characterize the effect of the envelope fragment fusion site in the P64k protein from Neisseria meningitidis several chimeric constructs were obtained. One variant consisted in the insertion of the E fragment from each Dengue serotype within the lipoil binding domain of the P64k, whereas the other was based on the fusion of the envelope fragment at the C-terminus of the same meningoccocal protein. The results of the expression study revealed the majoritary levels with the C-terminus fusion variants of each serotype. In contrast, the highest proportion of soluble protein was reached with the insertion variants independently of the viral serotype. On the other hand, a significant level of degradation was detected for the semipurified forms of the insertion variants being remarkable in the Dengue 2 construct. Finally, the recognition by Dengue murine antibodies was similar independently of the fusion site. Regarding these results, we can affirm the suitability of the C-terminus fusion variants for further vaccine development as well as for a diagnostic system. (C) 2003 Elsevier Inc. All rights reserved.