Bacterial superglue generates a full-length circumsporozoite protein virus-like particle vaccine capable of inducing high and durable antibody responses.

Abstract

BACKGROUND:

Malaria, caused by Plasmodium falciparum, continues to have a devastating impact on global health, emphasizing the great need for a malaria vaccine. The circumsporozoite protein (CSP) is an attractive target for a malaria vaccine, and forms a major component of RTS,S, the most clinically advanced malaria vaccine. The clinical efficacy of RTS,S has been moderate, yet has demonstrated the viability of a CSP-based malaria vaccine. In this study, a vaccine comprised of the full-length CSP antigen presented on a virus-like particle (VLP) is produced using a split-intein conjugation system (SpyTag/SpyCatcher) and the immunogenicity is tested in mice.

METHODS:

Full-length 3d7 CSP protein was genetically fused at the C-terminus to SpyCatcher. The CSP-SpyCatcher antigen was then covalently attached (via the SpyTag/SpyCatcher interaction) to Acinetobacter phage AP205 VLPs which were modified to display one SpyTag per VLP subunit. To evaluate the VLP-display effect, the immunogenicity of the VLP vaccine was tested in mice and compared to a control vaccine containing AP205 VLPs plus unconjugated CSP.

RESULTS:

Full-length CSP was conjugated at high density (an average of 112 CSP molecules per VLP) to AP205 SpyTag-VLPs. Vaccination of mice with the CSP Spy-VLP vaccine resulted in significantly increased antibody titres over a course of 7 months as compared to the control group (2.6-fold higher at 7 months after immunization). Furthermore, the CSP Spy-VLP vaccine appears to stimulate production of IgG2a antibodies, which has been linked with a more efficient clearing of intracellular parasite infection.

CONCLUSION:

This study demonstrates that the high-density display of CSP on SpyTag-VLPs, significantly increases the level and quality of the vaccine-induced humoral response, compared to a control vaccine consisting of soluble CSP plus AP205 VLPs. The SpyTag-VLP platform utilized in this study constitutes a versatile and rapid method to develop highly immunogenic vaccines. It might serve as a generic tool for the cost-effective development of effective VLP-vaccines, e.g., against malaria.

• Authors: Christoph M Janitzek, Sungwa Matondo, Susan Thrane, Morten A Nielsen, Reginald Kavishe, Steve B Mwakalinga, Thor G Theander, Ali Salanti, Adam F Sander
• Journal: Malaria journal (Malar J) Vol. 15 Issue 1 Pg. 545 (Nov 08 2016) ISSN: 1475-2875 [Electronic] England
• PMID: 27825348 (Publication Type: Journal Article)

Chemical References

• Antibodies, Protozoan
• Drug Carriers
• Immunoglobulin G
• Protozoan Proteins
• Vaccines, Subunit
• Vaccines, Synthetic
• Vaccines, Virus-Like Particle
• circumsporozoite protein, Protozoan

Topics

• Acinetobacter (virology)
• Animals
• Antibodies, Protozoan (blood)
• Antibody Formation
• Bacteriophages (chemistry)
• Cell Surface Display Techniques
• Drug Carriers
• Female
• Immunoglobulin G (blood)
• Mice, Inbred BALB C
• Protozoan Proteins (genetics, immunology)
• Vaccines, Subunit (administration & dosage, genetics, immunology)
• Vaccines, Synthetic (administration & dosage, genetics, immunology)
• Vaccines, Virus-Like Particle (administration & dosage, genetics, immunology)