Primary and Secondary Infections of Macaca fascicularis Monkeys with Asian and American Genotypes of Dengue Virus 2

The goal of this study was to compare the immune response and the protection capacity induced by the dengue virus 2 (DENV-2) American and Asian genotypes in Macaca fascicularis monkeys. Animals were infected with American or Asian DENV-2 strains and challenged 1 year later with a DENV-2 Asian genotype strain. The viremia and monkey antibody levels were similar for the different strains after primary and secondary infection; however, the functionality of the antibody response was different. A limited viral replication was demonstrated after the secondary infection in all the monkeys. No virus was isolated in tissue culture, while reverse transcription-PCR showed a late positive reaction in four of five challenged monkeys. The immunoglobulin M response pattern and the detection of antibodies to specific proteins by Western blotting supported the protection data. Despite the demonstration of the protective effect after homologous challenge, a strong anamnestic antibody response was observed. Dengue fever and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) are caused by any of four closely related but antigenically distinct dengue virus (DENV) serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Currently, dengue fever/DHF is the most important mosquito-borne viral disease affecting humans, and an estimated 2.5 billion people live in areas at risk of epidemic transmission (14).