Emergence of a new variant of dengue virus serotype 2 in Jazan region, southwestern Saudi Arabia

Background: Dengue virus (DENV) infection is a global economic and public health concern, particularly in tropical and subtropical countries where it is endemic. Saudi Arabia has seen an increase in DENV infections, especially in the western and southwestern regions. This study aims to investigate the genetic variants of DENV-2 that were circulating during a serious outbreak in Jazan region in 2019. Methods: A total of 482 serum samples collected during 2019 from Jazan region were tested with reverse transcription-polymerase chain reaction (RT-PCR) to detect and classify DENV; positive samples underwent sequencing and bioinformatics analyses. Results: Out of 294 positive samples, type-specific RT-PCR identified 58.8% as DENV-2 but could not identify 41.2%. Based on sequencing and bioinformatics analyses, the samples tested PCR positive in the first round but PCR negative in the second round were found to be a new genetic variant of DENV-2. The newly identified DENV-2 variant showed similarities to DENV-2 sequences reported in Malaysia, Singapore, Korea and China. The results revealed a new genetic variant of DENV-2 was circulating in Jazan region that was highly prevalent and drove the serious regional outbreak in 2019. Conclusions: The emergence of new DENV variants is a serious challenge for the dengue fever surveillance and control programmes in endemic areas. Therefore, further investigations and continuous surveillance of existing and new viral strains in the region are warranted.