A serological survey and characterization of Getah virus in domestic pigs in Thailand, 2017-2018

Getah virus (GETV) is a mosquito-borne RNA virus belonging to the family Togaviridae, genus Alphavirus. GETV infection causes diarrhoea and death in piglets, and reproductive failure and abortion in sows. This study conducted a serological survey of GETV infection among domestic pig populations in Thailand. ELISA was used to analyse 1,188 pig serum samples collected from 11 provinces of Thailand during 2017-2018, with 23.1% of the samples being positive for anti-GETV antibodies. The positive ratio of anti-GETV antibodies was significantly higher in nursery (67.9%) and older stages (84.5%) of pigs than in finishing stage (14.2%). Furthermore, we successfully isolated GETV from one pig serum, designated as GETV strain GETV/SW/Thailand/2017, and determined the complete genome sequence (11,689 nt). Phylogenetic analysis demonstrated that our isolate was different from the recent GETV group spreading among pig populations in East Asia and formed a cluster with two GETV strains, namely YN12031 (China, 2015) and LEIV16275Mar (Far-East Russia, 2007). We concluded that two different GETV groups are currently spreading among pig populations in Asian countries.

Mosquito-borne viruses, insect-specific flaviviruses (family Flaviviridae, genus Flavivirus), Banna virus (family Reoviridae, genus Seadornavirus), Bogor virus (unassigned member of family Permutotetraviridae), and alphamesoniviruses 2 and 3 (family Mesoniviridae, genus Alphamesonivirus) isolated from Indonesian mosquitoes

Mosquitoes transmit many kinds of arboviruses (arthropod-borne viruses), and numerous arboviral diseases have become serious problems in Indonesia. In this study, we conducted surveillance of mosquito-borne viruses at several sites in Indonesia during 2016-2018 for risk assessment of arbovirus infection and analysis of virus biodiversity in mosquito populations. We collected 10,015 mosquitoes comprising at least 11 species from 4 genera. Major collected mosquito species were Culex quinquefasciatus, Aedes albopictus, Culex tritaeniorhynchus, Aedes aegypti, and Armigeres subalbatus. The collected mosquitoes were divided into 285 pools and used for virus isolation using two mammalian cell lines, Vero and BHK-21, and one mosquito cell line, C6/36. Seventy-two pools showed clear cytopathic effects only in C6/36 cells. Using RT-PCR and next-generation sequencing approaches, these isolates were identified as insect flaviviruses (family Flaviviridae, genus Flavivirus), Banna virus (family Reoviridae, genus Seadornavirus), new permutotetravirus (designed as Bogor virus) (family Permutotetraviridae, genus Alphapermutotetravirus), and alphamesoniviruses 2 and 3 (family Mesoniviridae, genus Alphamesonivirus). We believed that this large surveillance of mosquitoes and mosquito-borne viruses provides basic information for the prevention and control of emerging and re-emerging arboviral diseases.