Dengue virus surveillance in Singapore reveals high viral diversity through multiple introductions and in situ evolution

• Published in: Infection, genetics and evolution Vol. 12; no. 1; pp. 77 - 85
• Main Authors: Lee, Kim-Sung, Lo, Sharon, Tan, Sharon Siok-Yin, Chua, Rachel, Tan, Li-Kiang, Xu, Helen, Ng, Lee-Ching
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01-01-2012; Elsevier
• Subjects: Adaptation; Aedes - virology; Animals; Arboviroses; Biological and medical sciences; Dengue - epidemiology; Dengue - virology; Dengue fever; Dengue fevers; Dengue Virus - classification; Dengue Virus - genetics; Dengue virus importations; Disease Outbreaks; Epidemiology. Vaccinations; Evolution, Molecular; General aspects; Genetic Variation; Genotype; Human viral diseases; Humans; In situ evolution; Infectious diseases; Medical sciences; Molecular epidemiology; Phylogeny; RNA, Viral - genetics; Sequence Analysis, DNA; Singapore; Singapore - epidemiology; Tropical viral diseases; Viral diseases; Viral Envelope Proteins - genetics; Asia; Singapore; In situ evolution; Dengue virus importations; Molecular epidemiology; Singapore; Dengue fever; Adaptation; Multiple; Dengue; In situ; Dengue virus; Flavivirus; Infection; Virus; Surveillance; Viral disease; Dengue group virus; Arbovirus disease; Evolution; Flaviviridae
• ISSN: 1567-1348; 1567-7257
• DOI: 10.1016/j.meegid.2011.10.012

► The circulating dengue viruses in Singapore are highly diverse. ► Multiple importations and in situ evolution contribute to viral diversity in Singapore. ► In situ evolution could possibly result in viruses with improved fitness.
Dengue fever, a vector-borne disease, has caused tremendous burden to countries in the tropics and sub tropics. Over the past 20years, dengue epidemics have become more widespread, severe and frequent. This study aims to understand the dynamics of dengue viruses in cosmopolitan Singapore. Envelope protein gene sequences of all four dengue serotypes (DENV-1–DENV-4) obtained from human sera in Singapore (2008–2010) revealed that constant viral introductions and in situ evolution contribute to viral diversity in Singapore and play important roles in shaping the epidemiology of dengue in the island state. The diversity of dengue viruses reported here could be a reflection of the on-going dengue situation in the region given Singapore’s location in a dengue hyperendemic region and its role as the regional hub for travels and trade. Though cosmopolitan genotype of DENV-2 has remained as the predominant strain circulating in Singapore, we uncovered evidence of in situ evolution which could possibly result in viruses with improved fitness. While we have previously shown that a switch in the predominant dengue serotype could serve as a warning for an impending outbreak, our current data shows that a replacement of a predominant viral clade, even in the absence of a switch in predominant serotype, could signal a possible increase in dengue transmission. The circulating dengue viruses in Singapore are highly diverse, a situation which could offer ample opportunities for selection of strains of higher fitness, thus increasing the risk of outbreaks despite a low Aedes population.