DNA vaccination of mice with a plasmid encoding Puumala hantavirus nucleocapsid protein mimics the B-cell response induced by virus infection

Inoculation of naked DNA has been applied for the development of prophylact ic and therapeutic vaccines against different viral infections. To study th e humoral immune response induced by DNA vaccination we cloned the entire n ucleocapsid protein-encoding sequence of the Puumala hantavirus strain Vran ica/Hallnas into the CMV promoter-driven expression unit of the plasmid pcD NA3, generating pcDNA3-VR1. A single dose injection of 50 mug of plasmid DN A into each M. tibialis anterior of BALB/c mice induced a high-titered anti body response against the nucleocapsid protein as documented 6 and 11 weeks after immunisation. PEPSCAN analysis of a serum pool of the pcDNA3-VR1-vac cinated animals revealed antibodies reacting with epitopes covering the who le nucleocapsid protein. The epitope-specificity of the immune response ind uced by DNA vaccination seems to reflect the antibody response in experimen tally virus-infected bank voles (the natural host of the Puumala virus) and humans. The data suggest that DNA Vaccination could be used for the identi fication of highly immunogenic epitopes in viral proteins. (C) 2000 Elsevie r Science B.V. All rights reserved.