Characterization of Fowlpox virus in chickens and bird-biting mosquitoes: a molecular approach to investigating Avipoxvirus transmission

Vector-Borne and Zoonotic Diseases

Chan

How

et al. 2020

Self Cite

Japanese encephalitis virus (JEV) and West Nile virus (WNV) are arboviruses primarily transmitted by Culex spp. mosquitoes. Birds are the primary hosts for JEV and WNV. Recent WNV outbreaks in Europe and United States and their association with migratory birds highlight the importance of understanding the feeding host preference of potential vectors for outbreak preparedness, especially in nonendemic settings. Singapore is nonendemic to JEV and WNV, but is a stopover site for migratory birds of the East Asian-Australasian Flyway. Therefore, we elucidated the feeding host range of Culex spp. mosquitoes captured in four natural (bird) habitats in Singapore from January 2011 to December 2012. We characterized feeding host DNA in field-caught mosquitoes using a PCR sequencing-based assay targeting the mitochondrial gene regions. Of 22,648 mosquitoes captured, 21,287 belonged to the Culex vishnui subgroup. The host DNA analysis showed that mosquitoes from the Cx. vishnui subgroup are opportunistic biters, feeding on a range of birds and mammals. Cx. vishnui subgroup, Culex sitiens and Culex bitaeniorhynchus, was primarily ornithophagic, although they fed opportunistically on mammals, including humans. Culex gelidus and Culex quinquefasciatus, in contrast, fed mainly on mammals. The presence of ornitho-and anthropophilic mosquito vectors and susceptible avian and mammalian hosts poses a risk spill-over transmission of JEV and WNV among humans, should these viruses be introduced through migratory birds and establish persistent transmission in resident birds and animal hosts in Singapore.

Section: Bloodmeal Identificationmentioning

confidence: 99%

Molecular Analysis of the Bloodmeals ofCulexspp. Mosquitoes at Natural Habitats in Singapore to Investigate the Potential Risk of Japanese Encephalitis Virus and West Nile Virus Transmission

Vector-Borne and Zoonotic Diseases

Chan

How

et al. 2020

Self Cite

“…We noticed moderately high Wolbachia infection in Culex quinquefasciatus which is a member of the Culex pipiens complex responsible for the transmission of lariasis worm disease in Singapore [87,88]. Surprisingly, between closely-related species, Culex pseudovishnui and Culex vishnui [96], we only found high percentage infection in the former. However, previous studies in India and Thailand showed a reverse pattern -infection in Cx.…”

Section: Discussionmentioning

confidence: 59%

Wolbachia Infection in Wild Mosquitoes (Diptera: Culicidae): Implications for Transmission Modes and Host-Endosymbiont Associations

Ding

Puniamoorthy

2020

Preprint

Background: Wolbachia is an intracellular bacterial endosymbiont found in most insect lineages. In mosquitoes, the endosymbiont’s influence on host reproduction and arboviral transmission has spurred numerous studies aimed at using Wolbachia-infection as a vector control technique. However, there exist several gaps in the literature regarding the natural Wolbachia infection across species, modes of transmission as well as the associations between various Wolbachia lineages and their hosts. This study aims to address these by exploring mosquito-Wolbachia associations and their evolutionary implications.Methods: We conducted tissue-specific PCR screening of Wolbachia infection in wild mosquitoes from Singapore using the wsp molecular marker. Tissues examined include leg, gut, and reproductive tissues. We also explored mosquito-Wolbachia associations using three methods – a tanglegram, distance-based, and event-based method, and inferred instances of vertical transmission and host shifts. Results: We screened 271 adult mosquitoes (41 species and 14 genera) for Wolbachia and found that 43.9% of all individuals harboured Wolbachia. Eight out of the 21 infected species were not previously reported. We detected Wolbachia infections predominantly in the reproductive tissues, a strong indication of vertical transmission. Despite this, Wolbachia infection rates vary widely within a mosquito host species. There was no clear signal of co-phylogeny between the mosquito hosts and the twelve putative Wolbachia strains observed in our study. Host shift events were also observed. Conclusions: Our results suggest that the mosquito-Wolbachia relationship is complex and that a combination of transmission modes and multiple evolutionary events likely explain the distribution of Wolbachia diversity observed across mosquito hosts. This has implications towards understanding Wolbachia’s diversity, ecology, and utility as a biocontrol method.

“…We noticed moderately high Wolbachia infection in Culex quinquefasciatus (62.5%) which is a member of the Culex pipiens complex responsible for the transmission of lariasis worm disease in Singapore [86,87]. Surprisingly, between two closely related species, Culex pseudovishnui and Culex vishnui [88], no Wolbachia infection was observed in the latter which has been found to harbour Japanese encephalitis virus in the Southeast Asian region [89]. However, studies in India and Thailand showed a reverse pattern, with Wolbachia infection present in Cx.…”

Section: Detection Of Wolbachia Infection and Distribution In Wild Momentioning

confidence: 82%

Wolbachia infection in wild mosquitoes (Diptera: Culicidae): implications for transmission modes and host-endosymbiont associations in Singapore

Ding

Puniamoorthy

2020

Preprint

Background: Wolbachia is an intracellular bacterial endosymbiont found in most insect lineages. In mosquitoes, the endosymbiont’s influence on host reproduction and arboviral transmission has spurred numerous studies aimed at using Wolbachia-infection as a vector control technique. However, there are several knowledge gaps in the literature and little is known about natural Wolbachia infection across species, transmission modes as well as the associations between various Wolbachia lineages and their hosts. This study aims to address them by exploring mosquito-Wolbachia associations and their evolutionary implications.Methods: We conducted tissue-specific PCR screening for Wolbachia infection in the leg, gut and reproductive tissues of wild mosquitoes from Singapore using the Wolbachia surface protein (wsp) molecular marker. Mosquito-Wolbachia associations were explored using three methods – a tanglegram, distance-based, and event-based method, and inferred instances of vertical transmission and host shifts. Results: Adult mosquitoes (271 specimens) representing 14 genera and 40 species were screened for Wolbachia. Overall, 21 species (51.2%) were found positive for Wolbachia, including Aedes (5 species) and Culex (5 species). Seven out of the 21 infected species were not previously reported: Aedes nr. fumidus, Aedes annandaelei, Uranotaenia obscura, Uranotaenia trilineata, Verrallina butleri, Verrallina sp., and Zeugnomyia gracilis. Wolbachia was predominantly detected in the reproductive tissues, an indication of vertical transmission. Despite this, Wolbachia infection rates vary widely within a mosquito host species. There is no clear signal of co-phylogeny between the mosquito hosts and the twelve putative Wolbachia strains observed in this study. Host shift events were also observed. Conclusions: Our results suggest that the mosquito-Wolbachia relationship is complex and that combinations of transmission modes and multiple evolutionary events likely explain the distribution of Wolbachia diversity observed across mosquito hosts. This has implications towards understanding Wolbachia’s diversity, ecology, and utility as a biocontrol method.