Serratia odorifera a Midgut Inhabitant of Aedes aegypti Mosquito Enhances Its Susceptibility to Dengue-2 Virus

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From: PLoS ONE(Vol. 7, Issue 7)
Publisher: Public Library of Science
Document Type: Article
Length: 8,866 words
Lexile Measure: 1470L

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Author(s): Anjali Apte-Deshpande 1 , Mandar Paingankar 1 , Mangesh D. Gokhale 2 , Dileep N. Deobagkar 1 , 3 , *

Introduction

The gut flora of the vertebrates and invertebrates represents one of the most widespread and ancient symbiotic association. This symbiosis provides important physiological functions to the host, including the synthesis of essential nutrients, resistance to colonizing pathogens and stimulation of immune system [1], [2]. In hematophagous arthropods, these symbionts are even thought to be critical for the host fitness because of the need for blood scarce nutrients.

The mosquito midgut is an immune competent organ and is the first point of contact between the vector and arboviruses. An understanding of the microbial community structure of the mosquito midgut will therefore be crucial to identify its role in virus entry, multiplication and in turn, vector susceptibility. Recent studies of the mosquito midgut have utilized both culture dependent and independent methods to detect diverse microbial community in this physiological niche [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15] (also see Table S1). These studies mainly focus on the bacterial diversity and prevalence of certain bacterial species in the midguts of different mosquitoes like Anopheles, Aedes and Culex. Some of these reports also discuss the change in the midgut microbiota during developmental stages of mosquitoes [12], [14]. A Recent report has shown that in-vitro interaction of La Crosse virus with the midgut bacteria, isolated from Ae. albopictus , significantly reduces the infectivity of La Crosse virus (transmitted by this vector) to Vero cells [15]. This study warrants further investigation of this phenomenon in living mosquitoes. Similarly, Cirimotich et al [13] have demonstrated refractoriness to Plasmodium infection due to the generation of reactive oxygen species by resident gut microbes. Barring few of these examples, not much is understood about the mechanism underlying the altered arboviral or parasite susceptibility due to presence of gut microbes in these vectors.

Aedes aegypti is a natural vector for a group of viruses such as chikungunya, dengue fever virus, yellow fever virus as well as protozoan parasite, Plasmodium gallinaceum . It has been demonstrated that strains of Ae. aegypti also support the complete development of the filarial worms Brugia malayi [16], Brugia pahangi [17], and Dirofilaria immitis [18]. In spite of its epidemiological importance in disease transmission, very limited studies are available on Ae. aegypti with respect to the identification of gut microflora and its interaction with the disease transmitting agent. Identification of the stable and transmissible gut inhabitant of such a vector would therefore be a crucial factor in understanding its susceptibility to battery of viruses and parasites.

We employed culture dependent approach to investigate the bacterial diversity of Ae. aegypti midgut. A screening study of the midgut bacteria of Ae. aegypti mosquitoes reared in the laboratory and collected from the field was carried out to identify the microbes that are stably present in the midgut of these mosquitoes. The status of the midgut microbial community was evaluated during developmental stages of these mosquitoes...

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Gale Document Number: GALE|A498245025