Phylogenetic reconstruction of dengue virus type 2 in Colombia

Abstract

Background Dengue fever is perhaps the most important viral re-emergent disease especially in tropical and sub-tropical countries, affecting about 50 million people around the world yearly. In Colombia, dengue virus was first detected in 1971 and still remains as a major public health issue. Although four viral serotypes have been recurrently identified, dengue virus type 2 (DENV-2) has been involved in the most important outbreaks during the last 20 years, including 2010 when the fatality rate highly increased. As there are no major studies reviewing virus origin and genotype distribution in this country, the present study attempts to reconstruct the phylogenetic history of DENV-2 using a sequence analysis from a 224 bp PCR-amplified product corresponding to the carboxyl terminus of the envelope (E) gene from 48 Colombian isolates. Results As expected, the oldest isolates belonged to the American genotype (subtype V), but the strains collected since 1990 represent the American/Asian genotype (subtype IIIb) as previously reported in different American countries. Interestingly, the introduction of this genotype coincides with the first report of dengue hemorrhagic fever in Colombia at the end of 1989 and the increase of cases during the next years. Conclusion After replacement of the American genotype, several lineages of American/Asian subtype have rapidly spread all over the country evolving in new clades. Nevertheless, the direct association of these new variants in the raise of lethality rate observed during the last outbreak has to be demonstrated.

Differential replication of dengue virus serotypes 2 and 3 in coinfections of C6/36 cells and Aedes aegypti mosquitoes

“…To assess whether one serotype might replicate more efficiently in C6/36HT cells, coinfections were performed with the strains DENV-2/3986 and DENV-3/3832; these strains were selected because they had been isolated recently (in 2006 and 2007, respectively), and serotypes 2 and 3 had been associated with the increase of severe forms of dengue in Colombia during the last decade [13,27]. At 96 hours post-infection, serotype 2 was found to replicate more efficiently (3.18×10 9 genomic copies) than serotype 3 (7.04×10 5 genomic copies).…”

“…Furthermore, strains of the genotype III of DENV-3 reappeared in 2001 [12]; these strains have also been associated with the presence of severe disease forms [16]. It is known that some DENV-2 genotypes might be more virulent [17], and in Colombia, these have been associated with recent epidemics [13]. DENV-3 it has also been associated with severe disease forms since its reappearance in 2001 [16].…”

“…This is of particular interest in Colombia, which has recorded the cocirculation of all four serotypes since 2006 [12]. In addition to this phenomenon, in Colombia, strains of the Asian genotype of DENV-2 were introduced in the 1990s; these were grouped into a new Asian-American genotype [13]. These DENV-2 strains have been associated with increased virulence [14] and have been replacing the strains of American origin [15].…”

Desarrollo de un método de transcripción reversa seguida de reacción en cadena de la polimerasa para la detección del virus de la fiebre amarilla

“…In Colombia, there is an enormous risk of receiving viruses from infected incoming travelers and a high probability of the co-circulation of flavivirus and yellow fever genotypes that are not detectable by routinely used molecular probes (3,8,10,(16)(17)(18)(19). No molecular epidemiology study of yellow fever has been performed in Colombia whose aim was to determine the genotype diversity that may result in misdiagnosis; therefore, the true number of cases may be higher than reported.…”

“…Tissue or serum samples may pass through several freeze-thaw cycles, decreasing the probability of virus isolation, causing genome degradation or fragmentation and resulting in false-negative results, especially in those samples with low viral copy numbers (1,3,10). For these reasons, we have developed a specific RT-PCR assay with novel sets of primers that match a highly conserved region of all yellow fever genomes reported to date; this assay is thus capable of detecting a wide range of genotypes (6,19,21). This conserved genome region has a low selective pressure and no role in the immune response or the virus-environment relationships.…”