Figure 3

Unrooted phylogenetic tree. The eukaryotic aspartic protease domain, PF00026 was searched against the PFAM database [37] and sequences under the nematode branch were retrieved. Sequences were aligned using MUSCLE [38] and highly similar sequences were removed from the alignment. An unrooted neighbor-joining tree was calculated from protein distances using the MEGA package [40, 41]. Gapped regions were excluded in a complete fashion and percentage bootstrap values from 500 replicates were derived. Numbers above branches indicate the relative frequency in which bipartitions were observed (only values above 50% are shown). Sequences used in the final alignment are labelled according to their accession number at UNIPROT. Organisms are indicated after the accession numbers, as followed: Ac, Ancylostoma caninum; Ace, Ancylostoma ceylanicum; Bm, Brugia malayi; Cb, Caenorhabditis briggsae; Ce, Caenorhabditis elegans; Hc, Haemonchus contortus; Mi, Meloidogyne incognita; Na; Necator americanus; Ov, Onchocerca volvulus; Sr, Strongyloides ratti; Ss, Strongyloides stercoralis. Major groups I-III referred to in the text and coloured differently. All the sequences which present the Cys-rich insertion are labelled with a star.