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

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.

Chikungunya virus Detection in Aedes aegypti and Culex quinquefasciatus during an Outbreak in the Amazon Region

“…Populations of Ae. aegypti males collected in Mexico [42] and Thailand [43] have also been identified to be naturally infected with CHIKV. It has been shown that the high vector competence of both Ae.…”

Current Arboviral Threats and Their Potential Vectors in Thailand

“…aegypti vector [ 42 ]. The E1:A226V mutation of CHIKV is present in mosquitoes from Thailand: Ubon Ratchathani, Chiang Rai, Chiang Mai, Nakhon Sawan, and Songkha provinces, while the E1: K211E mutation is found in samples from Nong Khai, Bangkok, Prachuap Khiri Khan, and Krabi Province [ 40 ].…”

“…Both male and female Ae. aegypti were found to carry CHIKV (E1: A226V and E1: K211E) infection, with infection rates of 0.85% and 3.28%, respectively [ 40 ]. However, infection rates rely on several parameters, may change from one mosquito species to another, and depend on the viral dose, temperature, etc.…”

Complete Coding Sequences of 22 East/Central/South African Genotype Chikungunya Virus Isolates from Thailand (2018 to 2019)

“…This mutation is associated with increased viral transmission in Aedes albopictus ( 5 ). The most recent CHIKV outbreak in Thailand was reported in 2018 to 2019 ( 6 , 7 ). To investigate the CHIKV genomes from this outbreak, we sequenced 22 existing CHIKV isolates from Thailand.…”