Making Sense of the Amblyomma maculatum Salivary Gland Proteome

Amblyomma maculatum is emerging as an arthropod of increasing medical, veterinary and economic significance.  It is found in the southern United States, with inland extensions into Oklahoma, Kansas, and Virginia where it infests and transmits infectious disease agents to humans, livestock, wild and domestic animal species.  However, very little information is available on the Sialoproteome of A. maculatum.   In this study, we used proteome approach to get a deeper insight into the expression of pharmacological active salivary gland proteins, with special emphasis on secretory peptides.  Salivary glands from unfed and partially fed females were homogenized and the soluble protein was extracted. Samples from each sample group were subjected to 2D electrophoresis, excised from the gel and digested using trypsin. The digested protein fragments were analyzed using LC-MS/MS and evaluated through multiple databases for sequence homology. Proteins were categorized based on homology information regarding protein family. Overall, nearly 15,900 sequences were found in the salivary glands of unfed and partially fed female ticks. Of these 15,900 nearly 12,000 lacked a secretory signal peptide indicating they were intracellular and not secreted into the host.  The remaining 4,000 sequences with the signal peptide are hypothesized to be secreted by the saliva.