Identification and molecular characterization of Wolbachia strains in natural populations of Aedes albopictus in China.
BACKGROUND
Aedes albopictus is naturally infected with Wolbachia spp., maternally transmitted bacteria that influence the reproduction of hosts. However, little is known regarding the prevalence of infection, multiple infection status, and the relationship between Wolbachia density and dengue outbreaks in different regions. Here, we assessed Wolbachia infection in natural populations of Ae. albopictus in China and compared Wolbachia density between regions with similar climates, without dengue and with either imported or local dengue.


RESULTS
To explore the prevalence of Wolbachia infection, Wolbachia DNA was detected in mosquito samples via PCR amplification of the 16S rRNA gene and the surface protein gene wsp. We found that 93.36% of Ae. albopictus in China were positive for Wolbachia. After sequencing gatB, coxA, hcpA, ftsZ, fbpA and wsp genes of Wolbachia strains, we identified a new sequence type (ST) of wAlbB (464/465). Phylogenetic analysis indicated that wAlbA and wAlbB strains formed a cluster with strains from other mosquitoes in a wsp-based maximum likelihood (ML) tree. However, in a ML tree based on multilocus sequence typing (MLST), wAlbB STs (464/465) did not form a cluster with Wolbachia strains from other mosquitoes. To better understand the association between Wolbachia spp. and dengue infection, the prevalence of Wolbachia in Ae. albopictus from different regions (containing local dengue cases, imported dengue cases and no dengue cases) was determined. We found that the prevalence of Wolbachia was lower in regions with only imported dengue cases.


CONCLUSIONS
The natural prevalence of Wolbachia infections in China was much lower than in other countries or regions. The phylogenetic relationships among Wolbachia spp. isolated from field-collected Ae. albopictus reflected the presence of dominant and stable strains. However, wAlbB (464/465) and Wolbachia strains did not form a clade with Wolbachia strains from other mosquitoes. Moreover, lower densities of Wolbachia in regions with only imported dengue cases suggest a relationship between fluctuations in Wolbachia density in field-collected Ae. albopictus and the potential for dengue invasion into these regions.
['Hu|Yaping|Y|', 'Xi|Zhiyong|Z|', 'Liu|Xiaobo|X|', 'Wang|Jun|J|', 'Guo|Yuhong|Y|', 'Ren|Dongsheng|D|', 'Wu|Haixia|H|', 'Wang|Xiaohua|X|', 'Chen|Bin|B|', 'Liu|Qiyong|Q|']
D000330:Aedes D000704:Analysis of Variance D000818:Animals D001425:Bacterial Outer Membrane Proteins D002681:China D002980:Climate D016000:Cluster Analysis D004269:DNA, Bacterial D003715:Dengue D005260:Female D016013:Likelihood Functions D008297:Male D000072138:Mosquito Vectors D058885:Multilocus Sequence Typing D010802:Phylogeny D016133:Polymerase Chain Reaction D015995:Prevalence D012336:RNA, Ribosomal, 16S D020577:Wolbachia
Wolbachia Aedes albopictus Infection Phylogenetic analysis Dengue virus MLST genes