A protein sequence was not deduced for this contig, but can be inspected in additional file 1. 20,000 ESTs from an adult salivary gland library were sequenced. These ESTs have been assembled using previously described ESTs from the fat body and midgut libraries of the same fly, thus totaling 62,251 ESTs, which Rabbit Polyclonal to Lamin A (phospho-Ser22) have been assembled into 16,743 clusters (8,506 of which had one or more EST from the salivary gland library). Coding sequences were obtained for 2,509 novel proteins, 1,792 of which had at least one EST expressed in the salivary glands. Despite library normalization, 59 transcripts were overrepresented in the salivary library indicating high levels of expression. This work presents a detailed analysis of the salivary protein families identified. Protein expression was confirmed by 2D gel electrophoresis, enzymatic digestion and mass spectrometry. Concurrently, an initial attempt to determine the immunogenic properties of selected salivary proteins was undertaken. Conclusions The sialome of em G. m. morsitans /em contains over 250 proteins that are possibly associated with blood feeding. This set includes alleles of previously described gene products, reveals new evidence that several salivary proteins are multigenic and identifies at least seven new polypeptide families unique to em Glossina /em . Most of these proteins have no known function and thus, provide a discovery platform for the identification of novel pharmacologically active compounds, innovative vector-based vaccine targets, and Betanin immunological markers of vector exposure. Background The superfamily Hippoboscoidea comprises higher flies (Suborder Brachycera Schizophora: Calyptrate), which includes the tsetse, louse flies, and the bird and bat flies [1]. These flies have in common the unusual ovoviviparous reproductive process. All adults are exclusively blood feeders Betanin on mammals or other vertebrates, suggesting that hematophagy is a monophyletic trait in this group [2]. The family Glossinidae has a single genus, em Glossina /em , which comprises 31 species and sub-species of tsetse flies. Tsetse (which means em fly /em in the south African Tswana language) are today found exclusively in sub-Saharan Africa and are of both medical and veterinary importance because they are vectors of African trypanosomes to humans and domesticated animals [3]. Surprisingly, blood is a Betanin very unbalanced meal, lacking many vitamins for example, and perhaps for this reason, tsetse flies have mutualistic endosymbionts that are required for successful fly reproduction, digestion and nutrition [4,5]. The intricate relationship between the parasites and the mutualistic endosymbionts indicate that the origin of blood feeding in this genus is ancient, probably during or before the mammal radiation of 60 million years ago (MYA). Indeed em Glossina /em fossils from 38 MYA were found in the Florissant formation (Colorado), and also in Germany, indicating these flies were probably distributed worldwide 30-40 MYA [2]. Blood Betanin sucking arthropods must deal with their hosts’ defense against blood loss (hemostasis based on blood clotting, platelet aggregation and vasoconstriction), as well as their defenses triggered by inflammation and immunity mechanisms. These defences may cause death to the insect or, at the least, interrupt bloodmeal acquistion. The saliva of haematophagous arthropods can counteract these barriers by using a complex mixture of pharmacologically active components, which are injected into the host skin during the probing and ingestion phases of feeding [6,7]. Accordingly, at the site of skin penetration, the hosts’ response is pharmacologically modified by these salivary agents, which may inadvertently lead to enhanced transmission of pathogens. For this reason, the salivary contents of these vectors are not only a source of novel pharmaceuticals, but also can provide vaccine targets to interrupt disease transmission [8]. In the past 9 years, analysis of the salivary transcriptomes of bloodfeeding arthropods, including several genera within the ticks [9], triatomines [10-12], fleas [13], sand flies [8,14], em Culicoides /em [15,16] and mosquitoes [17-21], have indicated that saliva contains a cocktail of 70 – 150 proteins (insects) to several hundreds of proteins (ticks, which feed for several days on their hosts). Because the evolution of blood feeding among insects occurred independently several times, the composition of the sialome differs substantially among insects not sharing a common blood feeding ancestor, representing a classical court case of convergent evolution thus. However, deviation among sialomes inside the equal family members and inside the even.