Inclusion of the murine IgGκ signal peptide increases the cellular immunogenicity of a simian adenoviral vectored Plasmodium vivax multistage vaccine
Introduction
The life cycle of Plasmodium parasites is known for its complexity, and as a result, immunity to malaria infections in vertebrates relies on both humoral and cellular immune responses. Early passive transfer experiments demonstrated the protective role of IgG antibodies derived from malaria immune adults when used as a therapeutic intervention [1]. Clinical trials of sporozoite inoculation have revealed that IFN-γ producing T cells are associated with protection against malaria [2]. Based on this evidence, a multistage vaccine capable of eliciting both cytophilic antibodies and antigen-specific T cells would likely enhance the protective efficacy of a comprehensive vaccination strategy.
The RTS,S/AS01 vaccine represents a significant breakthrough as the first P. falciparum malaria vaccine that has completed Phase 3 clinical trials [3]. However, RTS,S has reported low efficacy due in part to protection based primarily on antibodies against the circumsporozoite protein (CSP) central repeat region [4] present in pre-erythrocytic stage forms, which wane rapidly and require boosting immunizations to maintain efficacy [5]. The inclusion of erythrocytic stage targets to control parasites that evade liver clearance and enhancing cellular immunogenicity are likely necessary for developing an effective second generation of malaria vaccines.
Adenoviral vectored malaria vaccines have been able to improve the immunogenicity of protein-based vaccines [6], [7], [8], [9] and induce protective Plasmodium-specific CD8+ T cells in pre-clinical and clinical studies [10], [11], [12], but low induction of CD4+ T cell suggests further improvements to adenoviral vectors should be investigated [11]. Recent studies examining the induction of CD4+ T cells following vaccination with an Ad5 vector have shown that significantly lower frequencies of antigen-specific CD4+ T cells are induced when compared to acute infection, an effect that could be attributed to lower IL-2 signaling [13]. Increasing secretion or altering post-translational modifications of adenoviral transgene products might result in improved presentation of vaccine antigens to CD4+ T cells.
Signal peptides (SP), also referred to as signal sequences, are short peptides (∼20–30 residues) that can influence the targeting pathway of the protein and promote protein secretion or specific post-translational modifications such as glycosylation [14]. As a result, SP from highly secreted proteins have been used to improve protein secretion levels of recombinant proteins in cell lines [15], [16], [17], as well as for ectopic expression of endogenous adenoviral genes [18]. Recently, the inclusion of an SP into a DNA vaccine targeting HPV oncogenes was found to induce potent cellular and humoral immune responses that protected against tumor challenge [19]. Of the signal peptides used to improve transgene expression, the sequence derived from the murine immunoglobulin kappa (IgGκ) light chain (METDTLLLWVLLLWVPGSTG), is one of the most well characterized [15], [16], [17].
We hypothesized that the addition of the signal peptide derived from murine IgGκ light chain upstream of a transgene delivered via a recombinant adenovirus vector would improve the CD4+ T cell response to the transgene product in comparison to vaccination with the same recombinant vector without the signal peptide [10]. Here we demonstrate that the addition of the murine IgGκ SP improves the immunogenicity of an adenoviral vectored P. vivax multistage vaccine [20], [21] in mice by significantly increasing IFN-γ and IL-2 secretion by CD4+ T cells, and improving antibody avidity. To our knowledge, this is the first report of the insertion of a signal peptide sequence as part of an adenoviral transgene with the goal of improving the immunogenicity of an adenoviral vectored vaccine candidate.
Section snippets
Viral vectors
The DNA sequence encoding the hybrid cPvCSP/cPvMSP1 protein containing the C-terminal six-His tag was codon-optimized for mammalian expression and incorporated into a pShuttle plasmid between the CMV promoter and BGH polyadenylation signal. The constructed plasmid was further modified to introduce the N-terminal SP into the hybrid cPvCSP/cPvMSP1 protein. The oligonucleotide duplex encoding IgGκ light chain SP was cloned into KpnI restriction site upstream of the cPvCSP/cPvMSP1 transgene
The impact of the murine IgGκ signal peptide on protein secretion in vitro
The simian adenovirus 36 (SAd36) vector was selected for assessment of the effect of the insertion of the murine IgGκ light chain derived signal peptide on the adenoviral vector immunogenicity, as we have previously found SAd36 to exhibit higher immunogenicity than the standard Ad5 vector [10]. The SAd36 vector is replication deficient due to deletion of the E1 gene. A hybrid transgene encoding a chimeric P. vivax CSP (cPvCSP) linked to a chimeric P. vivax MSP1 (cPvMSP1) protein
Discussion
The development of an effective malaria vaccine able to induce strong and balanced CD4+ and CD8+ T cell responses, as well as cytophilic antibodies, remains elusive. At present, multiple vaccine platforms and delivery systems are being investigated to determine the optimal vaccination regimen to induce broad and long-lasting immunity to malaria. Clinical studies of the protein-based vaccine, RTS,S, have shown protective efficacy mainly mediated through the induction of antibodies [35]. However,
Conflicts of interest
None.
Funding
This research was supported by the National Institutes of Health, NIAID grants R56-AI103382-01A1 and R21-AI117459-01A1, and the Yerkes National Primate Research Center Base Grant No. RR00165 awarded by the National Center for Research Resources of the National Institutes of Health. This project was supported in part by ORIP/OD P51OD011132.
Acknowledgments
The authors would like to thank Dr. James Wilson for providing us with the SAd36 vector; Dr. Fidel Zavala for providing our group with P. vivax CSP VK210 repeat region transgenic P. berghei sporozoites for IFA slides; Dr. Mary Galinski for providing our group with P. vivax infected Saimiri boliviensis blood for IFA slides; Evan Dessasau III from Yerkes Histology Core for sectioning of murine lymph nodes; Dr. Deepa Kodandera from the Yerkes Molecular Pathology Core for sectioning, staining, and
References (57)
- et al.
A prime-boost immunization regimen based on a simian adenovirus 36 vectored multi-stage malaria vaccine induces protective immunity in mice
Vaccine
(2017) - et al.
The surprising complexity of signal sequences
Trends Biochem Sci
(2006) - et al.
Enhanced production of secretory glycoprotein VSTM1-v2 with mouse IgGkappa signal peptide in optimized HEK293F transient transfection
J Biosci Bioeng
(2016) - et al.
The tripartite leader sequence is required for ectopic expression of HAdV-B and HAdV-E E3 CR1 genes
Virology
(2017) - et al.
Targeting of adenovirus serotype 5 pseudotyped with short fiber from serotype 41 to c-erbB2-positive cells using bispecific single-chain diabody
J Mol Biol
(2009) - et al.
The polypeptides of adenovirus. I. Evidence for multiple protein components in the virion and a comparison of types 2, 7A, and 12
Virology
(1968) - et al.
The assessment of antibody affinity distribution by thiocyanate elution: a simple dose-response approach
J Immun Methods
(1995) - et al.
Clinical assessment of a novel recombinant simian adenovirus ChAdOx1 as a vectored vaccine expressing conserved Influenza A antigens
Mol Ther: J Am Soc Gene Ther
(2014) - et al.
Efficient induction of protective anti-malaria immunity by recombinant adenovirus
Vaccine
(1998) - et al.
Evaluation of a prime-boost vaccine schedule with distinct adenovirus vectors against malaria in rhesus monkeys
Vaccine
(2009)
Modulating antibody functionality in infectious disease and vaccination
Trends Mol Med
Dissecting polyclonal vaccine-induced humoral immunity against HIV using systems serology
Cell
Interleukin-2 at the crossroads of effector responses, tolerance, and immunotherapy
Immunity
Follicular helper T cells are essential for the elimination of plasmodium infection
EBioMedicine
Gamma-globulin and acquired immunity to human malaria
Nature
Protection against a malaria challenge by sporozoite inoculation
N Engl J Med
The future of the RTS, S/AS01 malaria vaccine: an alternative development plan
PLoS Med
Immunological mechanisms underlying protection mediated by RTS, S: a review of the available data
Malaria J
Seasonal vaccination against malaria: a potential use for an imperfect malaria vaccine
Malaria J
Adenoviral vectors as novel vaccines for influenza
J Pharm Pharmacol
Adenoviruses as gene/vaccine delivery vectors: promises and pitfalls
Expert Opin Biol Ther
Adenovirus-based vaccines for fighting infectious diseases and cancer: progress in the field
Hum Gene Ther
Development of chimpanzee adenoviruses as vaccine vectors: challenges and successes emerging from clinical trials
Expert Rev Vaccines
Protective CD8+ T-cell immunity to human malaria induced by chimpanzee adenovirus-MVA immunisation
Nat Commun
Prime-boost immunization with adenoviral and modified vaccinia virus Ankara vectors enhances the durability and polyfunctionality of protective malaria CD8+ T-cell responses
Infect Immun
Adenovirus serotype 5 vaccination results in suboptimal CD4 T helper 1 responses in mice
J Virol
Overcoming the refractory expression of secreted recombinant proteins in mammalian cells through modification of the signal peptide and adjacent amino acids
PloS One
Efficient production of CYTL1 protein using mouse IgGkappa signal peptide in the CHO cell expression system
Acta Biochim Biophys Sin (Shanghai)
Cited by (13)
IgGκ Signal Peptide Enhances the Efficacy of an Influenza Vector Vaccine against Respiratory Syncytial Virus Infection in Mice
2023, International Journal of Molecular Sciences
- 1
These authors contributed equally to this work.
- 2
Current address: Division of Leukemia and Lymphoma, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30307, United States.