Sculpting humoral immunity through dengue vaccination to enhance protective immunity

Abstract

Dengue viruses (DENV) are the most important mosquito transmitted viral pathogens infecting humans. DENV infection produces a spectrum of disease, most commonly causing a self-limiting flu-like illness known as dengue fever; yet with increased frequency, manifesting as life-threatening dengue hemorrhagic fever (DHF). Waning cross-protective immunity from any of the four dengue serotypes may enhance subsequent infection with another heterologous serotype to increase the probability of DHF. Decades of effort to develop dengue vaccines are reaching the finishing line with multiple candidates in clinical trials. Nevertheless, concerns remain that imbalanced immunity, due to the prolonged prime-boost schedules currently used in clinical trials, could leave some vaccinees temporarily unprotected or with increased susceptibility to enhanced disease. Here we develop a DENV serotype 1 (DENV-1) DNA vaccine with the immunodominant cross-reactive B cell epitopes associated with immune enhancement removed. We compare wild-type (WT) with this cross-reactivity reduced (CRR) vaccine and demonstrate that both vaccines are equally protective against lethal homologous DENV-1 challenge. Under conditions mimicking natural exposure prior to acquiring protective immunity, WT vaccinated mice enhanced a normally sub-lethal heterologous DENV-2 infection resulting in DHF-like disease and 95% mortality in AG129 mice. However, CRR vaccinated mice exhibited redirected serotype-specific and protective immunity, and significantly reduced morbidity and mortality not differing from naїve mice. Thus, we demonstrate in an in vivo DENV disease model, that non-protective vaccine-induced immunity can prime vaccinees for enhanced DHF-like disease and that CRR DNA immunization significantly reduces this potential vaccine safety concern. The sculpting of immune memory by the modified vaccine and resulting redirection of humoral immunity provide insight into DENV vaccine-induced immune responses.

A Mouse Monoclonal Antibody against Dengue Virus Type 1 Mochizuki Strain Targeting Envelope Protein Domain II and Displaying Strongly Neutralizing but Not Enhancing Activity

“…An improved vaccine antigen should contain epitopes that strongly induce neutralizing antibodies without inducing enhancing activities, such as 7F4, and minimize the presence of epitopes that induce enhancing antibodies, such as 3H12. Such an example, an antigen that reduces enhancing antibodies without altering neutralizing antibody induction capacity, was recently developed by manipulating immunodominant epitopes of the fusion peptide and EDIII (61,62). In addition, as suggested in the present study, it may be possible to use epitope manipulation to control IgG subclass profiles of induced antibodies; this is highly desirable, as enhancing activity is reduced, depending on the IgG subclass, in the presence of complement in in vitro assays (35,63).…”

High-Avidity and Potently Neutralizing Cross-Reactive Human Monoclonal Antibodies Derived from Secondary Dengue Virus Infection

“…The two-tailed Mann-Whitney test was used to determine the differences in K d , FRNT 50 , and relative binding activity after low-pH treatment between two groups, and the two-tailed Spearman correlation test was used to determine the relationship between K d and FRNT 50 by GraphPad Prism 5.0.…”

Virus-Like Particle Secretion and Genotype-Dependent Immunogenicity of Dengue Virus Serotype 2 DNA Vaccine

“…AfeI and StuI restriction enzyme sites were incorporated at the 5= and 3= termini of the cDNA amplicons, respectively. cDNA amplicons were digested with the AfeI and StuI enzymes and inserted into the AfeI-and StuI-cutting sites of the pVD1i expression vector plasmid (30) to obtain plasmids pVD2-American, pVD2-American/Asian, pVD2-Cosmopolitan, and pVD2-Sylvatic using DENV-2 strain S14635, BC100/98, BC145/97, and DakHD 10674 as the templates, respectively. A plasmid containing Asian 2 genotype DNA was not constructed because of the sequence similarity between the Asian 1 and Asian 2 genotypes, which have only three commonly shared nonconservative amino acid substitutions when the E-protein sequences are compared.…”

“…The proportion of non-EDIII (EDI-II-and prM-specific) IgG from vaccinated mouse serum was calculated by dividing the endpoint titer obtained from the specific knockout antigen (pVD2-Asian 1/D1 EDIII) by that obtained from WT antigen with the same serum sample. EDIII-specific IgG proportions were calculated from the equation 1 minus the proportion of non-EDIII-specific IgG, as previously described (14,30).…”

“…However, replacement of EDI-II of wild-type pVD2-Asian 1 with EDI-II of pVD2-Sylvatic resulted in a dramatic reduction in reactivity of more than 60%, suggesting that the epitopes located in EDI-II are the determinants highly targeted by antibodies elicited by the pVD2-Asian 1 vaccine. We also screened our VLPs of various genotypes for reactivity to a panel of well-characterized neutralizing murine MAbs (14,30,40) recognizing flavivirus group-, subgroup-, subcomplex-, and type-specific epitopes to investigate whether the VLPs expressed in vivo from DNA vaccines of the different DENV-2 genotypes contain B-cell epitopes that elicit antibodies with reactivities similar to the reactivities of these MAbs. As shown in Table 3, most of the MAbs were highly reactive to antigens on the VLPs of the different genotypes.…”