Replacing adenoviral vector HVR1 with a malaria B cell epitope improves immunogenicity and circumvents preexisting immunity to adenovirus in mice
Takayuki Shiratsuchi, … , Stefan Worgall, Moriya Tsuji
Takayuki Shiratsuchi, … , Stefan Worgall, Moriya Tsuji
Published September 1, 2010
Citation Information: J Clin Invest. 2010;120(10):3688-3701. https://doi.org/10.1172/JCI39812.
View: Text | PDF
Research Article Infectious disease

Replacing adenoviral vector HVR1 with a malaria B cell epitope improves immunogenicity and circumvents preexisting immunity to adenovirus in mice

Abstract

Although adenovirus (Ad) has been regarded as an excellent vaccine vector, there are 2 major drawbacks to using this platform: (a) Ad-based vaccines induce a relatively weak humoral response against encoded transgenes, and (b) preexisting immunity to Ad is highly prevalent among the general population. To overcome these obstacles, we constructed an Ad-based malaria vaccine by inserting a B cell epitope derived from a Plasmodium yoelii circumsporozoite (CS) protein (referred to as the PyCS-B epitope) into the capsid proteins of WT/CS-GFP, a recombinant Ad expressing P. yoelii CS protein and GFP as its transgene. Multiple vaccinations with the capsid-modified Ad induced a substantially increased level of protection against subsequent malaria challenge in mice when compared with that of unmodified WT/CS-GFP. Increased protection correlated with augmented antibody responses against the PyCS-B epitope expressed in the capsid. Furthermore, replacement of hypervariable region 1 (HVR1) of the Ad capsid proteins with the PyCS-B epitope circumvented neutralization of the modified Ad by preexisting Ad-specific antibody, both in vivo and in vitro. Importantly, the immunogenicity of the Ad-containing PyCS-B epitope in the HVR1 and a P. yoelii CS transgene was maintained. Overall, this study demonstrates that the HVR1-modifed Ad vastly improves upon Ad as a promising malaria vaccine platform candidate.

Authors

Takayuki Shiratsuchi, Urvashi Rai, Anja Krause, Stefan Worgall, Moriya Tsuji

×

Figure 7

Recognition and neutralization of P. yoelii sporozoites by serum from immunized mice.

Options: View larger image (or click on image) Download as PowerPoint
Recognition and neutralization of P. yoelii sporozoites by serum from im...
(A) Groups of naive BALB/c mice (5 per group) were immunized intramuscularly with 1 × 108 v.p. of various rAds at week 0, 1 × 109 v.p. of various rAds at week 3, and 1 × 1010 v.p. of various rAds at week 6, and then serum samples were prepared at week 10. IFA was done to determine anti-sporozoite antibody titers, using pooled serum samples at week 10. IFA titers were determined as the highest dilution producing fluorescence under a fluorescent microscope. Serum from WT/GFP was negative at the lowest dilution (200-fold dilution), and its titer is described as 100. (B) Neutralization of P. yoelii sporozoites in vitro. Sporozoites were incubated with CD81/HepG2 for 2 hours in the presence of 30-fold diluted pooled serum described in A. After incubation, uninfected sporozoites were washed out, and then the cells were cultured for 42 hours. The relative amount of parasite ribosomal RNA to human GAPDH mRNA was measured by real-time PCR. Data are shown as the mean ± the SD for triplicate cultures.