Analysis of cysteine peptidases. (A) Phylogenetic tree based on maximum likelihood analysis of a Dermacentor variabilis midgut protein and published tick Cathepsin L and B-like peptidase sequences. The transcript identified in this analysis is in bold (DvM). Phylogenetic analysis was conducted on protein alignments using Tree Puzzle version 5.2. Values at nodes represent calculated internal branch node support (1000 replications). (B) Multiple sequence alignment (CLUSTALX) of protein sequences identified in a cDNA library of unfed/2 d fed or 6 d fed D. variabilis midguts (DvM) and published sequences from other ticks found on Genbank. Arrowheads indicate catalytic residues. Diamonds represent predicted amino acids involved in catalysis. Shading represents 100% identity (black) or similarity (grey) among the sequences. Alignments were conducted using CLUSTALX. D. variabilis (Dv), Ixodes ricinus (Ir), Haemaphysalis longicornis (Hl), Rhipicephalus (Boophilus) microplus (Bm), R. appendiculatus (Ra), R. haemaphysaloides (Rh).