American Genotype Structures Decrease Dengue Virus Output from Human Monocytes and Dendritic Cells

Abstract

The dengue virus type 2 structures probably involved in human virulence were previously defined by sequencing the complete genome of both American and Southeast (SE) Asian genotype templates in patient serum (K. C. Leitmeyer et al., J. Virol. 73:4738-4747, 1999). We have now evaluated the effects of introducing a mutation in the envelope glycoprotein (E) gene and/or replacement of 5-and 3-nontranslated regions on dengue virus replication in human primary cell cultures. A series of chimeric infectious clones were generated containing different combinations of American and SE Asian genotype sequences. Some of the chimeric viruses had altered plaque morphology in mammalian cells; however, they replicated at similar rates in mosquito cells as measured by quantitative reverse transcription-PCR and plaque assay. Although susceptibility to virus infection varied from donor to donor in experiments using human macrophage and dendritic cells, we were able to measure consistent differences in viral RNA output per infected cell. Using this measurement, we demonstrated that the chimeric virus containing the E mutation had a lower virus output compared to the parental infectious clone. A larger reduction in virus output was observed for the triple mutant and the wild-type, American genotype virus from which chimeric inserts were derived. It appears that the three changes function synergistically, although the E mutation alone gives a lower output compared to the 5-and 3-terminal mutations. The data suggest that these changes may be responsible for decreased dengue virus replication in human target cells and for virulence characteristics during infection.

Variation in Inflammatory/Regulatory Cytokines in Secondary, Tertiary, and Quaternary Challenges with Dengue Virus

“…Results of these studies support the hypothesis that specific structural differences between the Southeast Asian and American genotypes may be involved in disease pathogenesis. [49][50][51][52][53] In this study, we compared only the ability of induction of the studied cytokines in secondary heterotypic infection between dengue serotypes and we used only the DV-2 A15 4PR 3PC6/36 HT Cuban strain (A15/81 strain) a Southeast Asian genotype. It would be interesting in future studies to address differences in the cellular immune response to the different strains of the four serotypes, in particular the American and Southeast Asian genotypes of DENV-2.…”

Lineage II of Southeast Asian/American DENV-2 is Associated with a Severe Dengue Outbreak in the Peruvian Amazon

“…aegypti compared with DENV-2 of the southeast Asian/ American genotype. 1,22,[36][37][38] Not surprisingly, given its higher fitness in both host and vector systems, southeast Asian/American DENV-2 has displaced American DENV-2 in many regions in the Americas. 36,39 Since 2000, the US Naval Medical Research Unit No.…”

Infectious clone construction of dengue virus type 2, strain Jamaican 1409, and characterization of a conditional E6 mutation

“…It should be noted that published reports on other DENV-2 ic constructs have an Ile at E6, but were not inhibited in production of IVs in mammalian cells after electroporation (Blaney et al, 2004;Kapoor et al, 1995;Kinney et al, 1997). However, DENV-2 IV production has also been shown previously to be influenced by the unique genetic make-up of the viral genome: specifically, a nucleotide alteration in the envelope gene resulting in an amino acid variation at E-390, together with variations in the 39 UTR, influenced DENV-2 replication in human cells (Cologna & Rico-Hesse, 2003). Therefore, the overall genetic make-up of the 1409 genome, and not just the E6 locus, may have an influence on translational efficiency and IV production.…”