Cell-mediated immune responses in humans after immunization with one or two doses of oral live attenuated typhoid vaccine CVD 909

Center for Vaccine Development, Department of Pediatrics, University of Maryland, Baltimore, MD 21201, USA.
Vaccine (Impact Factor: 3.49). 03/2007; 25(8):1416-25. DOI: 10.1016/j.vaccine.2006.10.040
Source: PubMed

ABSTRACT CVD 909 is a novel live attenuated S. Typhi oral vaccine candidate derived from strain CVD 908-htrA which constitutively expresses Vi. Herein we investigated whether the genetic manipulations involved in modifying CVD 908-htrA altered its ability to induce potent T-cell immune responses (CMI) after a single dose (five subjects) and, in a separate trial, whether a second dose (eight subjects) further enhanced its immunogenicity. In these clinical trials we observed that CVD 909 immunization elicits a wide array of CMI, including cytotoxic T cells (CTL), IFN-gamma, TNF-alpha and IL-10 (but not IL-2, IL-4 or IL-5) production, and proliferation to S. Typhi antigens. However, the administration of a second dose did not result in increases in CMI. These results suggest that the genetic manipulations to constitutively express Vi did not adversely affect the ability of CVD 909 to elicit a wide array of CMI responses. These observations add impetus for the continuing evaluation of CVD 909 as a typhoid vaccine candidate.

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Available from: Rezwanul Wahid, Jun 23, 2014
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    • "The emergence of multidrug-resistant strains of S. Typhi has added a sense of urgency to develop more effective typhoid vaccines (Levine et al. 2004). Despite recent advances (Wahid et al. 2007; Tacket et al. 2000), the pace of progress in this area of vaccinology is not fast enough and needs to be accelerated (Sztein 2007). Finally, there is a need of continuous surveillance and sharing of antimicrobial susceptibility data for Salmonella among countries worldwide (de Oliveira et al. in press) to ensure the effectiveness of control programmes (Pui et al. 2011). "
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