Identification of four genes expressed by feeding female Ixodes scapularis, including three with sequence similarity to previously recognized genes.

We created a cDNA library from feeding, female Ixodes scapularis ticks and screened the library with a subtracted probe to eliminate most genes common to feeding female and mating male I. scapularis ticks. Four unique genes were identified in this screen. One gene, Is 9, (represented by 16 cDNAs) was more highly expressed in female ticks. This gene encodes a putative glycine-rich protein, which matched a number of glycine-rich proteins including attachment cement proteins from Rhipicephalus appendiculatus. A second gene, Is 10 (represented by one cDNA) was also more highly expressed in female ticks, but did not match any other sequences in the GenBank database. The third gene, Is 11 (represented by one cDNA) was very similar to Drosophila sp. hsp68 and hsp70 genes and was expressed about equally in male and female ticks. The fourth gene, Is 12 (represented by two cDNAs) was also about equally expressed in male and female ticks, and was similar to a salivary gland gene from Ixodes ricinis. This gene also showed limited similarity to some cuticle genes from insects.