The Chimeric Protein Domain III-Capsid of Dengue Virus Serotype 2 (DEN-2) Successfully Boosts Neutralizing Antibodies Generated in Monkeys upon Infection with DEN-2

Abstract

Use of a heterologous prime-boost strategy based on a combination of nonreplicative immunogens and candidate attenuated virus vaccines against dengue virus in the same schedule is an attractive approach. These combinations may result in a condensed immunization regime for humans, thus reducing the number of doses with attenuated virus and the time spacing. The present work deals with the evaluation of the heterologous prime-boost strategy combining a novel chimeric protein (domain III-capsid) of dengue virus serotype 2 (DEN-2) and the infective homologous virus in the same immunization schedule in monkeys. Primed monkeys received one dose of infective DEN-2 and were then vaccinated with the recombinant protein. We found that animals developed a neutralizing antibody response after the infective dose and were notably boosted with a second dose of the chimeric protein 3 months later. The neutralizing antibodies induced were long lasting, and animals also showed the ability to induce a specific cellular response 6 months after the booster dose. As a conclusion, we can state that the domain III region, when it is properly presented as a fusion protein to the immune system, is able to recall the neutralizing antibody response elicited following homologous virus infection in monkeys. Further prime-boost approaches can be performed in a condensed regime combining the chimeric domain III-capsid protein and candidate live attenuated vaccines against DEN-2.Dengue is a mosquito-transmitted viral infection of high incidence worldwide. It is caused by four antigenically related but distinct dengue virus (DEN) serotypes which belong to the family Flaviviridae, genus Flavivirus (2), and which have been estimated to cause up to 100 million infections annually (11).Despite the high incidence of this disease, currently there is no vaccine against dengue. At present, the live attenuated viruses (LAVs) are the most advanced candidate vaccines against the infection. These candidate vaccines achieve a broad-spectrum immune response due to their replicative capacity (12,13,24). However, for the same characteristic, they have been associated with nonpredictable interactions among the four virus serotypes when they are administered in tetravalent formulations (13,23,24). This is why it becomes difficult to reach a satisfactory balance between immunogenicity and attenuation (18). To solve this problem, the administration of several spaced doses is required for current candidates based on this technology, including immunization programs that can take up to a year to be completed (13,(22)(23)(24).One of the attractive alternatives to solve the previous disadvantages is the use of a heterologous prime-boost strategy based on a combination of nonreplicative immunogens and candidate attenuated virus vaccines in the same schedule (25). These combinations may result in condensed immunization schedules for humans, thus reducing the number of doses with attenuated virus and the time spacing. On the other hand, the use of a suitable combination us...

Identification of human neutralizing antibodies that bind to complex epitopes on dengue virions

“…The organization of DENV E protein dimers on the surface of the infectious virus has been modeled using crystal structures of DENV recombinant E (rE) and cryo-EM reconstructions of the virion (8,10,26,27). Furthermore, neutralizing mouse mAbs have been mapped extensively to the rE protein, and DENV subunit vaccines using the rE protein are currently being developed (11)(12)(13)(14)(15)(28)(29)(30). We next assessed whether epitopes targeted by neutralizing Abs in human immune sera were preserved on the rE protein.…”

Antibodies targeting dengue virus envelope domain III are not required for serotype-specific protection or prevention of enhancement in vivo

“…Given the ability of anti-EDIII antibodies to contribute robustly to homologous protection with minimal cross-reactive binding, recombinant EDIII protein has been proposed as a vaccine candidate (Block et al, 2010; Valdes et al, 2009, 2011). In initial studies using a novel capsid-EDIII recombinant fusion protein, Valdes et al (2009) demonstrated a measurable humoral and cellular immune response; when the protein was used to boost a homologous infection, the antibody response was both potent and long-lasting (Valdes et al, 2011).…”

“…In initial studies using a novel capsid-EDIII recombinant fusion protein, Valdes et al (2009) demonstrated a measurable humoral and cellular immune response; when the protein was used to boost a homologous infection, the antibody response was both potent and long-lasting (Valdes et al, 2011). In a separate set of experiments, Block et al (2010) tested a similar hypothesis using an insect cell-derived, recombinant EDIII-based protein vaccine and found that vaccination of mice with tetravalent EDIII protein produced antibodies that exhibited both neutralizing and enhancing activity.…”

Dengue vaccine: an update on recombinant subunit strategies

“…In the second approach, monkeys received a single s.c. dose of DV2 and were boosted three months later with 100 μg of EDIIIC (Valdés et al, 2011). Administration of the recombinant proteins eff ectively boosted the neutralizing antibody responses elicited with the virus (Valdés et al, 2010;Valdés et al, 2011). Th ese antibodies persisted at high levels (PRNT 50>300) for at least six months aft er the boost dose.…”

“…In a fi rst approach, monkeys were primed with a single dose of DV2 and boosted fi ve months later with 300 μg of EDIII-P64k (Valdés et al, 2010). In the second approach, monkeys received a single s.c. dose of DV2 and were boosted three months later with 100 μg of EDIIIC (Valdés et al, 2011). Administration of the recombinant proteins eff ectively boosted the neutralizing antibody responses elicited with the virus (Valdés et al, 2010;Valdés et al, 2011).…”