Genetic and phenotypic characterization of sylvatic dengue virus type 4 strains

Abstract

Four serotypes of dengue virus (DENV 1-4) currently circulate between humans and domestic/peridomestic Aedes mosquitoes, resulting in 100 million infections per year. All four serotypes emerged, independently, from sylvatic progenitors transmitted among non-human primates by arboreal Aedes mosquitoes. This study investigated the genetic and phenotypic changes associated with emergence of human DENV-4 from its sylvatic ancestors. Analysis of complete genomes of 3 sylvatic and 4 human strains revealed high conservation of both the 5′- and 3′-untranslated regions but considerable divergence within the open reading frame. Additionally, the two ecotypes did not differ significantly in replication dynamics in cultured human liver (Huh-7), monkey kidney (Vero) or mosquito (C6/36) cells, although significant inter-strain variation within ecotypes was detected. These findings are in partial agreement with previous studies of DENV-2, where human strains produced a larger number of progeny than sylvatic strains in human liver cells but not in monkey or mosquito cells.

High rate of unrecognized dengue virus infection in parts of the rainforest region of Nigeria

“…Many of these areas are forested, with stagnant water and indiscriminate hollow containers that litter everywhere providing excellent breeding sites for increased vector activity. Mosquito-DENV-Human cycle has been reportedly found in nearly all urban and peri-urban environments throughout the tropics and subtropics (Rossi et al, 2012). Dengue in the tropical rain forest region has increased due to uncontrolled urbanization, lack of effective and sustainable vector control programs (Guzman et al, 2010).…”

Functional Analysis of Antibodies against Dengue Virus Type 4 Reveals Strain-Dependent Epitope Exposure That Impacts Neutralization and Protection

“…DENV-4 E genes were amplified by reverse transcription-PCR (RT-PCR) using primers (see Table S2 in the supplemental material), a high-fidelity Taq polymerase, and RNA extracted directly from infected C6/36 cells. Each amplicon was sequenced on both strands by conventional capillary sequencing on an Applied Biosystems 3730 genetic analyzer using previously reported primers (30,34). The resulting sequence reads were assembled, and the E gene sequences were aligned using the Lasergene suite (DNAStar).…”

“…Additional complexity occurs within each serotype, as genotypes vary by up to 3% at the amino acid level (28,29). DENV-4 has been suggested to have four distinct genotypes (I, II, III, and sylvatic), whose circulation patterns differ in time and space: genotype I includes strains from the Philippines, Thailand, Vietnam, Malaysia, Sri Lanka, and India; genotype II is composed of two lineages with strains from Thailand, Malaysia, Taiwan, and the Americas; genotype III includes Thai strains from 1997 to 2001; sylvatic strains were isolated from monkeys or mosquitoes in the 1970s in Malaysia (30). Although sylvatic DENV strains show the greatest sequence differences among the genotypes within a serotype, these viruses still can replicate and cause disease in humans (30)(31)(32).…”

Mapping the Human Memory B Cell and Serum Neutralizing Antibody Responses to Dengue Virus Serotype 4 Infection and Vaccination

“…FJ882599.1), available in GenBank database (http://www.ncbi.nlm.nih.gov/nuccore/228539113) or a sylvatic E protein sequence (Malaysia 1973; NCBI accession no. JF262780) (37). Recombinant subgenomic A plasmids were synthesized, and then viral assembly and rescue were performed as described above for generation of rDENV4.…”