Persistent Wolbachia and cultivable bacteria infection in the reproductive and somatic tissues of the mosquito vector Aedes albopictus.
BACKGROUND
Commensal and symbiotic microbes have a considerable impact on the behavior of many arthropod hosts, including hematophagous species that transmit pathogens causing infectious diseases to human and animals. Little is known about the bacteria associated with mosquitoes other than the vectorized pathogens. This study investigated Wolbachia and cultivable bacteria that persist through generations in Ae. albopictus organs known to host transmitted arboviruses, such as dengue and chikungunya.


RESULTS
We used culturing, diagnostic and quantitative PCR, as well as in situ hybridization, to detect and locate bacteria in whole individual mosquitoes and in dissected tissues. Wolbachia, cultivable bacteria of the genera Acinetobacter, Comamonas, Delftia and Pseudomonas co-occurred and persisted in the bodies of both males and females of Ae. albopictus initially collected in La Réunion during the chikungunya outbreak, and maintained as colonies in insectaries. In dissected tissues, Wolbachia and the cultivable Acinetobacter can be detected in the salivary glands. The other bacteria are commonly found in the gut. Quantitative PCR estimates suggest that Wolbachia densities are highest in ovaries, lower than those of Acinetobacter in the gut, and approximately equal to those of Acinetobacter in the salivary glands. Hybridization using specific fluorescent probes successfully localized Wolbachia in all germ cells, including the oocytes, and in the salivary glands, whereas the Acinetobacter hybridizing signal was mostly located in the foregut and in the anterior midgut.


CONCLUSIONS
Our results show that Proteobacteria are distributed in the somatic and reproductive tissues of mosquito where transmissible pathogens reside and replicate. This location may portend the coexistence of symbionts and pathogens, and thus the possibility that competition or cooperation phenomena may occur in the mosquito vector Ae. albopictus. Improved understanding of the vectorial system, including the role of bacteria in the vector's biology and competence, could have major implications for understanding viral emergences and for disease control.
Zouache
Karima
K
Université de Lyon, Lyon, France.
Voronin
Denis
D
Tran-Van
Van
V
Mousson
Laurence
L
Failloux
Anna-Bella
AB
Mavingui
Patrick
P
D000330:Aedes / Q000382:microbiology*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D005260:Female; D005836:Genitalia, Female / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D007303:Insect Vectors; D016133:Polymerase Chain Reaction; D012098:Reproduction; D020577:Wolbachia / Q000302:isolation & purification*
D017931:DNA Primers