This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: IAI.00356-07v1 75/8/3769    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chinchilla, M. Articles by Galen, J. E. Search for Related Content PubMed PubMed Citation Articles by Chinchilla, M. Articles by Galen, J. E.

Enhanced Immunity to Plasmodium falciparum Circumsporozoite Protein (PfCSP) by Using Salmonella enterica Serovar Typhi Expressing PfCSP and a PfCSP-Encoding DNA Vaccine in a Heterologous Prime-Boost Strategy ^,

Magaly Chinchilla,^1,3 Marcela F. Pasetti,^1,2 Sandra Medina-Moreno,^1,3, Jin Yuan Wang,¹ Oscar G. Gomez-Duarte,^1, Rick Stout,⁴ Myron M. Levine,^1,2,3 and James E. Galen^1,3*

Center for Vaccine Development,¹ Departments of Pediatrics,² Medicine, University of Maryland School of Medicine, Baltimore, Maryland,³ Bioject Inc., Portland, Oregon⁴

Received 7 March 2007/ Returned for modification 4 April 2007/ Accepted 2 May 2007

Two Salmonella enterica serovar Typhi strains that express and export a truncated version of Plasmodium falciparum circumsporozoite surface protein (tCSP) fused to Salmonella serovar Typhi cytolysin A (ClyA) were constructed as a first step in the development of a preerythrocytic malaria vaccine. Synthetic codon-optimized genes (t-csp1 and t-csp2), containing immunodominant B- and T-cell epitopes present in native P. falciparum circumsporozoite surface protein (PfCSP), were fused in frame to the carboxyl terminus of the ClyA gene (clyA::t-csp) in genetically stabilized expression plasmids. Expression and export of ClyA-tCSP1 and ClyA-tCSP2 by Salmonella serovar Typhi vaccine strain CVD 908-htrA were demonstrated by immunoblotting of whole-cell lysates and culture supernatants. The immunogenicity of these constructs was evaluated using a "heterologous prime-boost" approach consisting of mucosal priming with Salmonella serovar Typhi expressing ClyA-tCSP1 and ClyA-tCSP2, followed by parenteral boosting with PfCSP DNA vaccines pVR2510 and pVR2571. Mice primed intranasally on days 0 and 28 with CVD 908-htrA(pSEC10tcsp2) and boosted intradermally on day 56 with PfCSP DNA vaccine pVR2571 induced high titers of serum NANP immunoglobulin G (IgG) (predominantly IgG2a); no serological responses to DNA vaccination were observed in the absence of Salmonella serovar Typhi-PfCSP priming. Mice primed with Salmonella serovar Typhi expressing tCSP2 and boosted with PfCSP DNA also developed high frequencies of gamma interferon-secreting cells, which surpassed those produced by PfCSP DNA in the absence of priming. A prime-boost regimen consisting of mucosal delivery of PfCSP exported from a Salmonella-based live-vector vaccine followed by a parenteral PfCSP DNA boosting is a promising strategy for the development of a live-vector-based malaria vaccine.

Published ahead of print on 14 May 2007.

Supplemental material for this article may be found at http://iai.asm.org/.

Editor: D. L. Burns

Present address: Institute of Human Virology, Division of Clinical Research, University of Maryland, 725 Lombard St., Baltimore, MD 21201.

Present address: Department of Pediatrics, University of Iowa Children's Hospital, 200 Hawkins Dr., Iowa City, IA 52242.