RESUMEN
Dengue diseases are a group of infectious diseases that have been widespread throughout the world for several decades. Dengue outbreaks have occurred in many parts of the world, including Southeast Asia. The outbreak and the severity of the diseases depend on many factors including dengue genotype. Data on the genetic variation of dengue virus is highly informative for dengue protection plans and vaccine development. In this study, we focused on the analyses of genetic variation and amino acid changes of the whole coding sequences in two dengue strains isolated from Aedes mosquitoes in Bangkok, Thailand, an endemic area. The strains were identified as belonging to dengue virus serotype 1 (DENV-1) genotype I, and have unique nucleotide sequences. In the recombinant analysis, these strains were identified as recombinants derived from Chinese counterparts for both the major (DENV-1 genotype I) and the minor (DENV-1 genotype IV) parental strains. The recombination event occurred within the prM and E genes. This corresponded with the result of multiple alignments where several amino acid residues between the recombination breakpoints in the strains were identical to those in DENV-1 genotype IV. Several of the amino acid substitutions also have changed the amino acid properties, which might affect viral infection and antigenicity. These results provide insight into the genetic variation of DENV in this endemic area, which might have been involved in the dengue outbreak and high numbers of dengue haemorrhagic fever and dengue shock syndrome cases in Thailand in 2015.
Asunto(s)
Aedes/virología , Virus del Dengue/clasificación , Virus del Dengue/genética , Dengue/epidemiología , Filogenia , Recombinación Genética , Animales , Secuencia de Bases , Dengue/virología , Virus del Dengue/aislamiento & purificación , Femenino , Variación Genética , Genoma Viral , Genotipo , ARN Viral/genética , Análisis de Secuencia de ADN , Serogrupo , TailandiaRESUMEN
Dengue virus serotype 3 (DENV-3) can cause all forms of dengue diseases and is a predominant serotype in many countries. This serotype is classified into five genotypes: I-V. Genotypes I-III have widely spread throughout the world, whereas genotypes IV and V are rare. Despite the impact on the spread of dengue diseases, only a few studies have reported the characteristics of DENV present in mosquito vectors. Hence, this study aimed to identify DENV-3 genotypes and reveal genetic variation of this virus presented in field-caught mosquitoes collected from endemic areas in Thailand during 2011-2015. First, we examined the effectiveness of the E gene sequence on DENV-3 genotyping, with results supporting the use of this gene for genotype identification. Then, we sequenced this gene in ten DENV-3 strains isolated from mosquitoes. The results showed that eight and two samples were genotypes III and V, respectively, and that they are closely related to DENV-3 isolated from Southeast and East Asian samples. The translated E gene sequences showed 25 unique amino acid (AA) residues located at 23 positions. Eight out of 25 residues have different chemical properties compared to the conserved AAs that are distributed across the three domains functioning in virus-host interaction. Hence, our study reports the first DENV-3 genotype V in Thailand, with these viruses potentially influencing both the disease severity and epidemic potential of DENV-3.
Asunto(s)
Culicidae/virología , Virus del Dengue/genética , Genotipo , Mosquitos Vectores/virología , Filogenia , Secuencia de Aminoácidos , Animales , Virus del Dengue/clasificación , Virus del Dengue/aislamiento & purificación , Expresión Génica , Variación Genética , Interacciones Huésped-Patógeno , Humanos , Serina Endopeptidasas/clasificación , Serina Endopeptidasas/genética , Serogrupo , Tailandia , Proteínas del Envoltorio Viral/clasificación , Proteínas del Envoltorio Viral/genética , Proteínas no Estructurales Virales/clasificación , Proteínas no Estructurales Virales/genéticaRESUMEN
This report is the first to characterise the complete coding sequence of a dengue virus serotype 4 (DENV-4) genotype I that was isolated from field-caught mosquitoes from an endemic area in Thailand in June 2013. The sequence was assembled from high-throughput sequencing reads generated by Illumina HiSeq. Three out of four observed intra-sample variants caused an amino acid variation in C, NS2B, and NS5 genes. The C4279T variant located in the NS2B gene can indirectly affect the proteolytic activity of the NS3 protein. The sequence provided in this study might be useful for the epidemiological study of DENV-4.