Phylogeny of the Symbiont Wolbachia in Mosquitoes and Its Potential Interactions with Arbovirus in the Mosquito
Date Issued
2004
Date
2004
Author(s)
Tsai, Kun-Hsien
DOI
en-US
Abstract
Abstract
Wolbachia are maternally inherited bacteria that infect a wide range of arthropods as well as filarial worms. The infection usually results in reproductive distortions of the host, primarily cytoplasmic incompatibility, parthenogenesis, and feminization. This study showed that Wolbachia infection (15/29; 51.72%) was prevalent among field-caught mosquitoes in Taiwan. Each Wolbachia isolate derived from specific mosquitoes can be classified as a specific group and even a subgroup. Because there were still some isolates which did not belong to any known subgroup, more subgroups were expected to be identified. Investigation on tissue tropism of Wolbachia in either Aedes albopictus or Armigeres subalbatus revealed that Wolbachia were extensively distributed within the host. Of which, the ovary was the organ most susceptible to Wolbachia infection. Among 15 mosquito species infected by Wolbachia, 6 and 9 species were assigned to group A and group B, respectively. The 6 species belonging to group A Wolbachia were further classified into 3 sub-groups (AlbA, Gen, and Omi) while 9 species of group B Wolbachia were classified into 5 sub-groups (Ann, Con, Mur, Neo and Pip). The phylogenetic analysis also revealed the occurrence of several novel sub-groups of Wolbachia in mosquitoes used in this study. In addition, wsp gene has been identified in mosquitoes collected from different geographic locations in Taiwan. In this study, anti-Wolbachia antiserum was produced by using Wolbachia wsp protein, that had been expressed from a conserved region of wsp gene of Ar. subalbatus. Existence of Wolbachia either in salivary glands or ovaries was recognized by indirect immunofluorescent antibody test (IFA), demonstrating that the induced antiserum is suitable for identifying localization of Wolbachia in mosquito tissues. Intracellular bacteria have been described in several species of mosquitoes, but their relationships with the hosts and effects on virus transmission have not yet been elucidated; which have been examined by using intrathoracic inoculation of JE virus into Ar. subalbatus in this study. Based on examinations by both immunofluorescence antibody test (IFA) and electron microscopy (EM), Wolbachia was mainly distributed in ovaries where as JE virus was in salivary glands. On salivary glands, Wolbachia were observed in both distal and proximal parts of lateral lobes, and distal part of the median lobe. Meanwhile, both Wolbachia and JE virus can also be seen within the same cell of salivary glands; which has provided a model to elucidate the relationships between Wolbachia and JE virus. In fact, infection rates between mosquitoes with or without Wolbachia infection showed no difference in either salivary glands or ovaries. The infection rates were usually low in JE virus-infected F1 progenies of Ar. subalbatus with or without infection of Wolbachia. The results of plague assay showed that daily titers of JE virus were not significantly different in either Wolbachia-infected or free Ar. subalbatus.
Subjects
Wolbachia
共生物
蚊蟲
交互作用
蟲媒病毒
親緣關係
mosquitoes
phylogeny
interaction
arbovirus
Type
thesis