Transcriptomic analysis of the salivary glands of the Gulf Coast tick, Amblyomma maculatum (Acari: Ixodidae)

Ticks are obligate ecto-parasites that rank second only to mosquitoes as vectors of infectious agents to humans. Tick-borne infectious diseases are caused by a heterogonous array of organisms, including rickettsiae, ehrlichiae, spirochetes, tularemia, other bacteria, viruses and protozoa. Tick salivary glands serves as the organ of osmoregulation in ticks and are critical to the biological success of ticks both during extended period off the host and also during the feeding periods on the host. The salivary glands are the sites of pathogen development and saliva is the route of transmission. Tick saliva has a plethora of pharmacologically active components with anti-complement, anti-inflammatory and anti-histaminic activities as well as variety of other factors that inhibit the host immune response. We developed transcriptome profiles of the Gulf Coast tick (Amblyomma maculatum) by constructing normalized complementary DNA libraries from unfed and partially fed salivary glands. We randomly sequenced 1000 clones of each normalized cDNA libraries and annotated all the new identified ESTs. We further investigated the functional role of Serine protease inhibitor in tick feeding using RNA interference. Results of gene suppression in A. maculatum salivary glands will be discussed.