Arboviral screening of invasive Aedes species in northeastern Turkey: West Nile virus circulation and detection of insect-only viruses

Abstract

Background The recent reports of Aedes aegypti and Ae . albopictus populations in Turkey, in parallel with the territorial expansion identified in several surrounding countries, have raised concerns about the establishment and re-establishment of these invasive Aedes mosquitoes in Turkey. This cross-sectional study was performed to detect Aedes aegypti and Ae . albopictus in regions of recent incursions, and screen for viral pathogens known to be transmitted elsewhere by these species. Methodology Mosquitoes were collected at several locations in Artvin, Rize and Trabzon provinces of the Black Sea region during 2016–2017, identified morphologically, pooled and analyzed via generic or specific nucleic acid amplification assays. Viruses in positive pools were identified by product sequencing, cell culture inoculation and next generation sequencing (NGS) in selected specimens. Principal findings The study group comprised 791 specimens. Aedes albopictus was the most abundant species in all locations (89.6%), followed by Ae . aegypti (7.8%) and Culex pipiens (2.5%). Mosquitoes were screened for viruses in 65 pools where fifteen (23.1%) were reactive. The infecting strains was identified as West Nile virus (WNV) in 5 pools (7.7%) with Ae . albopictus or Cx . pipiens mosquitoes. The obtained WNV sequences phylogenetically grouped with local and global lineage 1 clade 1a viruses. In 4 (6.2%) and 6 (9.2%) pools, respectively, cell fusing agent virus (CFAV) and Aedes flavivirus (AEFV) sequences were characterized. NGS provided a near-complete AEFV genome in a pool of Ae . albopictus . The strain is provisionally called “AEFV-Turkey”, and functional analysis of the genome revealed several conserved motifs and regions associated with virus replication. Merida-like virus Turkey (MERDLVT), a recently-described novel rhabdovirus, was also co-detected in a Cx . pipiens pool also positive for WNV. Conclusions/Significance Invasive Aedes mosquitoes are established in certain locations of northeastern Turkey. Herein we conclusively show the role of these species in WNV circulation in the region. Biosurveillance is imperative to monitor the spread of these species further into Asia Minor and to detect possible introduction of pathogens.

High Transmission Potential of West Nile Virus Lineage 1 for Cx. pipiens s.l. of Iran

“…In addition, lineage 1 of WNV has been recently detected in blood donors of Pakistan (east of Iran) [31] and in mosquito pools, Aedes albopictus and Cx. pipiens s.l., in Turkey (northwest of Iran) [32]. Other similar investigations have also proved the circulation of WNV lineage 1 in Turkey, bordered with Iran [33][34][35].…”

“…Vector competence assays should be combined with an active monitoring of WNV lineage 1 circulation in Iran [31,32]. We used a lineage 1 strain to assess vector competence of Cx.…”

“…Thus, for a better understanding of the mechanisms behind the maintenance and transmission of WNV, the present study was designed to evaluate the vector competence of Cx. pipiens s.l., the principal vector of WNV [37], and one of the most prevalent species reported [38] for the highly invasive and recently reported WNV lineage 1 in the region [31,32], based on measuring the infection, dissemination, and transmission rates of Cx. pipiens s.l.…”

Enhanced West Nile Virus Circulation in the Emilia-Romagna and Lombardy Regions (Northern Italy) in 2018 Detected by Entomological Surveillance

“…The possible involvement of Ae. albopictus as a bridge vector in the WNV cycle was deduced due to WNV positive pools collected in the field in the U.S. (21) and Turkey (22), and the vectorial competence demonstrated in experimental studies (23,24). The possible vector role of Ae.…”

Molecular Determinants of West Nile Virus Virulence and Pathogenesis in Vertebrate and Invertebrate Hosts

“…A recent study performed by Akiner and colleagues (2019) in Turkey, found WNV by PCR in Ae. albopictus collected in the field [52]. However, WNV has not as yet been isolated from Ae.…”