Genotypes of the dengue virus in patients with dengue infection from Sabah, Malaysia

Abstract

Dengue fever is an arthropod-borne viral disease caused by the Dengue virus (genus Falvivirus, family Flaviviridae). It has rapidly spread all over the world affecting approximately 400 million people annually. Human dengue infection is caused by four types of closely related viruses (also called serotypes) namely DENV-1, DENV-2, DENV-3, and DENV-4, all of which can be all found in Sabah, Malaysia. Each serotype can then be divided into unique groups based on its genotypes. In Malaysia, dengue has been reported as the most prevalent disease of the country with a ratio of 328.3 cases per 100,000 populations. Exacerbating this further, it was also recently reported in 2017 of the emergence of a newly identified Asian lineage dengue virus i.e. type 3 genotype II (D3GII) in Malaysia. We have aimed, through this study, to examine the serotypes and the genotypes of dengue virus circulating in Sabah. This study was conducted for a period of 8 months i.e. from January to August 2017. A total of 52 NS1 (50.9% were males and 49.1% were females) positive dengue patient serum samples were genotyped. Viral RNA was extracted from serum using QIAamp viral RNA mini kit and DNA sequencing was done on Applied Biosystems 3730xl DNA analyzer. The results showed that serotype DENV-3 was the most predominant dengue circulating virus in Sabah with 23 cases detected. These were further grouped under three genotypes namely D3GI (1 case), D3GII (14 cases) and D3GIII (8 cases). Serotype DENV-1 was the second most common circulating virus in Sabah with 17 cases and grouped under two genotypes, D1Gia (15 cases) and D1Gic (2 cases), respectively. On the other hand, only one genotype (D4GII) was detected for DENV-4 (9 cases), and two genotypes (D2 Cosmopolitan Clade I and D2 Cosmopolitan Clade Ib) for DENV-2, each with one case per genotype, respectively. Understanding of genotype diversity will be useful in designing strategies for dengue management in epidemiological surveillance and vaccine design.