Japanese Encephalitis Virus in Mosquitoes and Swine in Yunnan Province, China 2009–2010

Abstract

The residential regions of Yunnan province, canton of Jing Hong, in China were surveyed for Japanese encephalitis virus (JEV) infection in mosquito and swine vectors to determine the frequency of JEV-carrying zoonotic vectors in 2009-2010. A total of 21,500 mosquitoes were collected and divided by species, and brain tissue was collected from 108 stillborn piglets. The infection rates for the different JEV species were 13.2% for Culex tritaeniorhynchus, 2.7% for Anopheles sinensis, 0.7% for Armigeres subalbatus, and 18.5% for stillborn piglets. The complete genomes of two JEV samples that were collected in different seasons and different regions, Yunnan 0901 and Yunnan 0902, were sequenced from a pool of Culex mosquitoes and stillborn piglets that had been collected randomly from several piggeries. Multiple sequence alignment with 24 fully-sequenced genes and 93 complete sequences of the JEV-encoded E gene revealed nucleotide homologies ranging from 97.2-99.6% and 94.5-99.7% in mosquitoes and piglets, respectively, and deduced amino acid homologies ranging from 97.4-98.1% and 96.0-98.2%, respectively. Phylogenetic analyses of the Yunnan 0901 and Yunnan 0902 strains' full-length genomes and E gene sequences indicated that these strains are most closely related to six Chinese SA14-derived viruses, and distantly related to the Australian FU, vellore P20778, and Japanese Ishikawa strains, and the previously isolated YN86-B8639 strains. The phylogenetic relationships based on the full-length genome were similar to those found for the E gene, indicating that phylogenetic analysis of the E gene will be a useful approach for genotyping of JEV, but not to better understand the potential changes in the biological characteristics and genetic relationship of JEV isolates.

Discovery of flavivirus-derived endogenous viral elements inAnophelesmosquito genomes supports the existence ofAnopheles-associated insect-specific flaviviruses

“…In North America, West Nile virus (WNV) was detected in Anopheles punctipennis (Bernard et al 2001; Kulasekera et al 2001). In Asia, Japanese encephalitis virus was detected in Anopheles sinensis (Feng et al 2012; Liu et al 2013). In Europe, Anopheles maculipennis was found positive for WNV (Filipe 1972; Kemenesi et al 2014) and Usutu virus (Calzolari et al 2013).…”

Armigeres subalbatus incriminated as a vector of zoonotic Brugia pahangi filariasis in suburban Kuala Lumpur, Peninsular Malaysia

“…subalbatus is commonly found close to human dwellings especially in sub-urban areas with poor sanitation that contain polluted water such as septic tanks [6]. This species has been known to be a vector of Japanese encephalitis virus [7]. It has also been reported to be a vector of filarial worm Wuchereria bancrofti in India [8] and the dog heartworm Dirofilaria immitis in Peninsular Malaysia [9].…”

Mosquitoes of Western Yunnan Province, China: Seasonal Abundance, Diversity, and Arbovirus Associations

“…The western borderland of Yunnan Province is a known epidemic area for JE [1,48], so detecting JEV in mosquito species that have been previously associated with JEV transmission was not surprising [2,3,8,19,20,41]. The 13 strains of JEV isolated in the present study were all determined to be genotype 1, which is consistent with the recent isolation of genotype 1 JEV in the cerebrospinal fluid samples from JE patients in this area [49].…”

“…Human cases of Japanese encephalitis (JE) occur commonly in Yunnan Province [1] and Japanese encephalitis virus (JEV) (Genus Flavivirus, Family Flaviviridae ), Dengue virus (DENV) (Genus Flavivirus, Family Flaviviridae ), Chikungunya virus (CHIKV) (Genus Alphavirus , Family Togaviridae ), Sindbis virus (SINV) (Genus Alphavirus , Family Togaviridae ), Getah virus (GETV) (Genus Alphavirus , Family Togaviridae ), Batai virus (BATV) (Genus Orthobunyavirus , Family Bunyaviridae ), Banna virus (BAV) (Genus Seadornavirus , Family Reoviridae ), Yunnan orbivirus (YUOV) (Genus Obivirus , Family Reoviridae ) and several other viruses have been isolated from human patients and from mosquitoes collected in Yunnan Province [2-18]. Previous investigations describing mosquitoes and their association with arboviruses [3-8,10,14,16-21], have been limited to summer months and do not provide information about the ecology of vectors and viruses during periods when mosquito and virus activity is low. This information is critical for preventative vector-control interventions aimed at reducing virus amplification in subsequent seasons.…”