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Preclinical Assessment of Viral Vectored and Protein Vaccines Targeting the Duffy-Binding Protein Region II of Plasmodium Vivax.

de Cassan SC, Shakri AR, Llewellyn D, Elias SC, Cho JS, Goodman AL, Jin J, Douglas AD, Suwanarusk R, Nosten FH, Rénia L, Russell B, Chitnis CE, Draper SJ - Front Immunol (2015)

Bottom Line: The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax.We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants).Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay.

View Article: PubMed Central - PubMed

Affiliation: The Jenner Institute, University of Oxford , Oxford , UK.

ABSTRACT
Malaria vaccine development has largely focused on Plasmodium falciparum; however, a reawakening to the importance of Plasmodium vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII - including human adenovirus serotype 5 (HAdV5), chimpanzee adenovirus serotype 63 (ChAd63), and modified vaccinia virus Ankara (MVA) vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants). Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII, and have recently entered clinical trials, which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans.

No MeSH data available.


Related in: MedlinePlus

Indirect IFA using serum from adenovirus-MVA PvDBP_RII immunized mice and rabbits. (A) Indirect IFA using sera from PvDBP_RII and OVA control immunized mice (green) and microscope slides containing fixed P. vivax-infected cells obtained from patients in Thailand. Representative images are shown for both sets of sera. Nuclei were stained with DAPI. The merge plus bright field are also shown. (B) ZiKa rabbits (n = 4) were immunized with HAdV5-PvDBP_RII on day 0 and MVA-PvDBP_RII on day 56. Serum was harvested before immunization (day 0) and 28, 56, and 70 days post-adenovirus administration. Serum IgG titers were determined by endpoint ELISA. Individual responses are shown and the solid line indicates the mean. The dotted line indicates the cut-off for a positive response – samples tested at 1:100 dilution that did not show an OD405 nm reading above negative control sera are plotted below this line. Rabbits immunized with the same vectors encoding OVA showed no detectable responses in the same ELISA assay (not shown). (C) Indirect IFA as in (A) using sera from the PvDBP_RII and OVA immunized rabbits (green). Two representative images are shown for both sets of sera.
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Figure 5: Indirect IFA using serum from adenovirus-MVA PvDBP_RII immunized mice and rabbits. (A) Indirect IFA using sera from PvDBP_RII and OVA control immunized mice (green) and microscope slides containing fixed P. vivax-infected cells obtained from patients in Thailand. Representative images are shown for both sets of sera. Nuclei were stained with DAPI. The merge plus bright field are also shown. (B) ZiKa rabbits (n = 4) were immunized with HAdV5-PvDBP_RII on day 0 and MVA-PvDBP_RII on day 56. Serum was harvested before immunization (day 0) and 28, 56, and 70 days post-adenovirus administration. Serum IgG titers were determined by endpoint ELISA. Individual responses are shown and the solid line indicates the mean. The dotted line indicates the cut-off for a positive response – samples tested at 1:100 dilution that did not show an OD405 nm reading above negative control sera are plotted below this line. Rabbits immunized with the same vectors encoding OVA showed no detectable responses in the same ELISA assay (not shown). (C) Indirect IFA as in (A) using sera from the PvDBP_RII and OVA immunized rabbits (green). Two representative images are shown for both sets of sera.

Mentions: The in vitro binding inhibition assay utilizes rDBP, and does not confirm that vaccine-induced antibodies are capable of recognition of native antigen within the P. vivax parasite. In order to assess this, indirect IFAs were performed using slides prepared from the blood of P. vivax infected Thai patients. Slides were probed with serum taken 2 weeks after the final vaccination from mice immunized with the ChAd63-PvDBP_RII and MVA-PvDBP_RII (ML) vectors (AM regime) outlined above in Figure 1B. All of the sera tested from PvDBP_RII immunized mice were positive by IFA with a punctate staining pattern, suggesting binding of antibody to PvDBP antigen within the micronemes of daughter merozoites (Figure 5A). We also immunized rabbits with the HAdV5 and MVA vectors expressing PvDBP_RII. These rabbit sera recognized PvDBP_RII antigen by ELISA, with responses after the priming immunization showing a different kinetic to mice (Figure 5B), but similar to that seen in rabbits in previous studies with the AM regime (45, 49). Serum from these rabbits, but not from vector immunized controls, also recognized P. vivax schizonts with a punctate staining pattern (Figure 5C).


Preclinical Assessment of Viral Vectored and Protein Vaccines Targeting the Duffy-Binding Protein Region II of Plasmodium Vivax.

de Cassan SC, Shakri AR, Llewellyn D, Elias SC, Cho JS, Goodman AL, Jin J, Douglas AD, Suwanarusk R, Nosten FH, Rénia L, Russell B, Chitnis CE, Draper SJ - Front Immunol (2015)

Indirect IFA using serum from adenovirus-MVA PvDBP_RII immunized mice and rabbits. (A) Indirect IFA using sera from PvDBP_RII and OVA control immunized mice (green) and microscope slides containing fixed P. vivax-infected cells obtained from patients in Thailand. Representative images are shown for both sets of sera. Nuclei were stained with DAPI. The merge plus bright field are also shown. (B) ZiKa rabbits (n = 4) were immunized with HAdV5-PvDBP_RII on day 0 and MVA-PvDBP_RII on day 56. Serum was harvested before immunization (day 0) and 28, 56, and 70 days post-adenovirus administration. Serum IgG titers were determined by endpoint ELISA. Individual responses are shown and the solid line indicates the mean. The dotted line indicates the cut-off for a positive response – samples tested at 1:100 dilution that did not show an OD405 nm reading above negative control sera are plotted below this line. Rabbits immunized with the same vectors encoding OVA showed no detectable responses in the same ELISA assay (not shown). (C) Indirect IFA as in (A) using sera from the PvDBP_RII and OVA immunized rabbits (green). Two representative images are shown for both sets of sera.
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Figure 5: Indirect IFA using serum from adenovirus-MVA PvDBP_RII immunized mice and rabbits. (A) Indirect IFA using sera from PvDBP_RII and OVA control immunized mice (green) and microscope slides containing fixed P. vivax-infected cells obtained from patients in Thailand. Representative images are shown for both sets of sera. Nuclei were stained with DAPI. The merge plus bright field are also shown. (B) ZiKa rabbits (n = 4) were immunized with HAdV5-PvDBP_RII on day 0 and MVA-PvDBP_RII on day 56. Serum was harvested before immunization (day 0) and 28, 56, and 70 days post-adenovirus administration. Serum IgG titers were determined by endpoint ELISA. Individual responses are shown and the solid line indicates the mean. The dotted line indicates the cut-off for a positive response – samples tested at 1:100 dilution that did not show an OD405 nm reading above negative control sera are plotted below this line. Rabbits immunized with the same vectors encoding OVA showed no detectable responses in the same ELISA assay (not shown). (C) Indirect IFA as in (A) using sera from the PvDBP_RII and OVA immunized rabbits (green). Two representative images are shown for both sets of sera.
Mentions: The in vitro binding inhibition assay utilizes rDBP, and does not confirm that vaccine-induced antibodies are capable of recognition of native antigen within the P. vivax parasite. In order to assess this, indirect IFAs were performed using slides prepared from the blood of P. vivax infected Thai patients. Slides were probed with serum taken 2 weeks after the final vaccination from mice immunized with the ChAd63-PvDBP_RII and MVA-PvDBP_RII (ML) vectors (AM regime) outlined above in Figure 1B. All of the sera tested from PvDBP_RII immunized mice were positive by IFA with a punctate staining pattern, suggesting binding of antibody to PvDBP antigen within the micronemes of daughter merozoites (Figure 5A). We also immunized rabbits with the HAdV5 and MVA vectors expressing PvDBP_RII. These rabbit sera recognized PvDBP_RII antigen by ELISA, with responses after the priming immunization showing a different kinetic to mice (Figure 5B), but similar to that seen in rabbits in previous studies with the AM regime (45, 49). Serum from these rabbits, but not from vector immunized controls, also recognized P. vivax schizonts with a punctate staining pattern (Figure 5C).

Bottom Line: The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax.We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants).Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay.

View Article: PubMed Central - PubMed

Affiliation: The Jenner Institute, University of Oxford , Oxford , UK.

ABSTRACT
Malaria vaccine development has largely focused on Plasmodium falciparum; however, a reawakening to the importance of Plasmodium vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII - including human adenovirus serotype 5 (HAdV5), chimpanzee adenovirus serotype 63 (ChAd63), and modified vaccinia virus Ankara (MVA) vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants). Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII, and have recently entered clinical trials, which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans.

No MeSH data available.


Related in: MedlinePlus