Genetic Characterization of Chikungunya Virus in Field-Caught Aedes aegypti Mosquitoes Collected during the Recent Outbreaks in 2019, Thailand

Proawpilart Intayot; Atchara Phumee; Rungfar Boonserm; Sriwatapron Sor-Suwan; Rome Buathong; Supaporn Wacharapluesadee; Narisa Brownell; Yong Poovorawan; Padet Siriyasatien

doi:10.3390/pathogens8030121

Genetic Characterization of Chikungunya Virus in Field-Caught Aedes aegypti Mosquitoes Collected during the Recent Outbreaks in 2019, Thailand

Pathogens. 2019 Aug 2;8(3):121. doi: 10.3390/pathogens8030121.

Authors

Proawpilart Intayot¹, Atchara Phumee^{2

3}, Rungfar Boonserm³, Sriwatapron Sor-Suwan³, Rome Buathong⁴, Supaporn Wacharapluesadee², Narisa Brownell³, Yong Poovorawan⁵, Padet Siriyasatien⁶

Affiliations

¹ Medical Science Program, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
² Thai Red Cross Emerging Infectious Diseases-Health Science Centre, World Health Organization Collaborating Centre for Research and Training on Viral Zoonoses, Chulalongkorn Hospital, Bangkok 10330, Thailand.
³ Vector Biology and Vector Borne Disease Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
⁴ Bureau of Epidemiology, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand.
⁵ Center of Excellence in Clinical Virology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
⁶ Vector Biology and Vector Borne Disease Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. padet.s@chula.ac.th.

Abstract

Chikungunya virus (CHIKV) is a mosquito-borne virus belonging to the genus Alphavirus. The virus is transmitted to humans by the bite of infected female Aedes mosquitoes, primarily Aedes aegypti. CHIKV infection is spreading worldwide, and it periodically sparks new outbreaks. There are no specific drugs or effective vaccines against CHIKV. The interruption of pathogen transmission by mosquito control provides the only effective approach to the control of CHIKV infection. Many studies have shown that CHIKV can be transmitted among the Ae. aegypti through vertical transmission. The previous chikungunya fever outbreaks in Thailand during 2008-2009 were caused by CHIKV, the East/Central/South African (ECSA) genotype. Recently, there have been 3794 chikungunya cases in 27 provinces reported by the Bureau of Epidemiology of Health Ministry, Thailand during 1 January-16 June 2019; however, the cause of the re-emergence of CHIKV outbreaks is uncertain. Therefore, the aims of this study were to detect and analyze the genetic diversity of CHIKV infection in field-caught mosquitoes. Both female and male Ae. aegypti were collected from endemic areas of Thailand, and CHIKV detection was done by using E1-nested RT-PCR and sequencing analysis. A total of 1646 Ae. aegypti samples (900 females and 746 males) were tested. CHIKV was detected in 54 (3.28%) and 14 samples (0.85%) in female and male mosquitoes, respectively. Seventeen samples of female Ae. aegypti collected from the Ubon Ratchathani, Chiang Rai, Chiang Mai, Nakhon Sawan, and Songkhla provinces found mutation at E1: A226V. Interestingly, E1: K211E mutation was observed in 50 samples collected from Nong Khai, Bangkok, Prachuap Khiri Khan, and Krabi. In addition, the phylogenetic tree indicated that CHIKV in Ae. aegypti samples were from the Indian Ocean Clade and East/South African Clade. Both clades belong to the ECSA genotype. The information obtained from this study could be used for prediction, epidemiological study, prevention, and effective vector control of CHIKV. For instance, a novel CHIKV strain found in new areas has the potential to lead to a new outbreak. Health authorities could plan and apply control strategies more effectively given the tools provided by this research.

Keywords: Aedes aegypti; Chikungunya virus; Thailand; genetic characterization.