Recently, many of these studies have been assembled into collection databases [2, 3] allowing analyses that examine RepSox cost patterns of essential genes across multiple organisms [4]. In organisms in which a genome wide essentiality survey has not been completed,

additional approaches have been used to predict essential genes. If gene essentiality has been determined in a closely related model organism, orthology between genes can predict shared essentiality [5–10]. Alternatively, systems biology approaches examine the global enzymatic and metabolic requirements of the organism. Among these are studies which define a minimal genome for a generic bacterial organism [11–13], or model the total metabolic interactions of the cell [14, 15]. For organisms with no functional genomics information in nearby species, methods based purely on gene sequence are being developed, though these provide lower accuracy than functional comparisons [16, 17]. Among the purely sequence based methods, gene conservation across taxa is the strongest indicator of gene essentiality [11, 16, 18, 19]. Genes whose protein sequences have been tightly conserved across lineages are assumed to be more likely to be important to the survival of the organism [20]. Each of the essential gene prediction methods described above requires different levels of a priori information about the target organism KU-57788 cost or closely related organisms.

As the amount of functional genomics information available decreases, predicting essential genes and drug targets becomes a significantly more difficult task. Here we present the results of our analysis of one such organism having no such functional data, the Wolbachia endosymbiont of Brugia malayi, (wBm). B. malayi is a parasitic filarial SCH727965 order nematode of humans which, along with Wuchereria bancrofti and Onchocerca volvulus, are the causative agents of lymphatic filariasis and onchocerciasis, more commonly known as elephantiasis and river blindness, respectively. Together, filarial parasites infect approximately 150 million people worldwide Metalloexopeptidase with 1.5

billion at risk of infection [21]. Current treatments utilize diethylcarbamazine, benzimidazoles (e.g., albendazole) and avermectins (e.g., ivermectin), however, these treatments are predominately only effective during the larval stages of the parasite [22]. Because the life-span of the adult worm is up to 15 years, long treatment courses are required to effectively eliminate the infection. Additionally, the emergence of drug resistance is becoming increasingly apparent [23, 24]. The α-proteobacterium Wolbachia is an obligate endosymbiont of most filarial nematodes, and in several, including B. malayi, is required for worm viability. Clearance of the Wolbachia by antibiotics results in worm growth retardation, infertility and killing, while antibiotic treatment of non-Wolbachia carrying nematode species has no effect [25, 26].