Dengue epidemics increasingly pose a public health problem in most countries of the tropical and subtropical areas. A safe and effective live dengue vaccine is still not available. To explore an alternative vaccine strategy, we employed the highly attenuated, replication-deficient MVA as a vector to construct recombinants expressing the highly immunogenic C-terminally truncated DEN2 or DEN4 envelope glycoprotein, approximately 80% of the full-length. Each of these recombinants elicited an elevated antibody response to DEN2 or DEN4 in mice following the booster inoculation, as detected by radio-immunoprecipitation. However, only recombinant MVA-DEN2 80%E, but not MVA-DEN4 80%E, induced a neutralizing antibody response in mice. The MVA-DEN2 80% E recombinant was chosen to further evaluate its ability to induce resistance to wild type DEN2 challenge in monkeys. Monkeys immunized twice with recombinant MVA-DEN2 80% E developed a low to moderate antibody response and were partially protected against DEN2 challenge, as determined by the viremia pattern. Importantly, the subsequent study showed that all four monkeys immunized with the recombinant in a three dose schedule developed an increased level of DEN2 neutralizing antibodies and were completely protected against DEN2 challenge. The results of this study showed that monkeys responded to an immunization schedule of 3 inoculations of the replication-deficient MVA recombinant and monkeys so immunized were resistant to homotypic dengue challenge. The potential efficacy and safety of recombinant MVA-DEN2 80% E to protect monkeys against dengue infection suggests that construction and evaluation of MVA recombinants expressing other serotypes of dengue virus E for use in a tetravalent vaccine strategy might be warranted.
| Anez, German; Men, Ruhe; Eckels, Kenneth H et al. (2009) Passage of dengue virus type 4 vaccine candidates in fetal rhesus lung cells selects heparin-sensitive variants that result in loss of infectivity and immunogenicity in rhesus macaques. J Virol 83:10384-94 |
