Identification of adjuvants for clinical trials performed with Plasmodium falciparum AMA1 in rabbits | BMC Immunology | Full Text

Identification of adjuvants for clinical trials performed with Plasmodium falciparum AMA1 in rabbits | BMC Immunology | Full Text



BMC Immunology

Identification of adjuvants for clinical trials performed with Plasmodium falciparum AMA1 in rabbits

• Sumera Younis, 
• Bart W. Faber, 
• Clemens H.M. Kocken & 
• Edmond J. Remarque 

BMC Immunologyvolume 20, Article number: 25 (2019) | Download Citation

Abstract

Background

In this study, seven adjuvants were compared for use with Plasmodium falciparumDiCo-Apical Membrane Antigen 1 (Pf-DiCo-AMA1), with the aim to identify an ideal adjuvant which yields high antibody titres and potentially broadens the responses in clinical trials. The following adjuvant formulations were evaluated: SE, SE-GLA, Liposomes, Liposomes-GLA, CoVaccine HT™, ImSaVac-P and ImSaVac-P o/w. The study was performed in rabbits, which were immunized with FVO-AMA1 in combination with one of the seven adjuvants. Antibody levels (humoral responses) and functional activity of the antibodies induced against malaria vaccine candidate AMA1 were evaluated. Thus, in this study the ideal adjuvant is expected to induce high functional antibody levels, a long-lived response, and a broad cross-strain activity.

Results

AMA1 formulated in all adjuvants was immunogenic. However, the magnitude of the immune responses differed between the seven adjuvants. The highest IgG levels were observed for the CoVaccine HT™ group, this was statistically significant for all four AMA1 variants versus all other adjuvant groups. No differences were observed in the breadth of the humoral response, i.e., increased recognition of AMA1 variants. Also, Growth Inhibition Activity (GIA) for both Plasmodium falciparumstrains (FCR3 – homologous to FVO AMA1 protein and NF54 – heterologous to FVO AMA1 protein) were significantly higher in the CoVaccine HT™ group as compared to the other adjuvant groups.

Conclusions

In brief, all seven vaccine – adjuvant formulations were immunogenic. The magnitude of the immune responses differed between the seven adjuvants. No statistically significant differences were observed in the breadth of the humoral response, nor in longevity of the response. Nevertheless, AMA1 formulated in CoVaccine HT™ appeared as the best adjuvant for use in clinical trials.