Identification and Characterization of a Differentially Expressed Gene (07E12) in the Infective Larvae of the Parasitic Nematode Ascaris suum

BACKGROUND Parasitic nematodes cause animal and human diseases of major socio-economic importance worldwide. The suppression of parasite development at particular developmental stages could provide an alternative approach for nematode control. In this study, Ascaris suum was used as a model system in the study of the differentially expressed genes in the infective L3 stage. METHODS The gene (07E12) was screened and identified from the subtractive cDNA library for the infective larvae of Ascaris suum using real-time quantitative PCR. Then, the full-length cDNA of 07E12 was characterized by 3' and 5' rapid amplification of cDNA ends (RACE). The characteristics of the gene were further analyzed using bioinformatic analyses. RESULTS The results showed that the gene 07E12 was differentially expressed in the third-stage larvae of A. suum and its expression level in the infective larvae was much higher than in other stages. It was shown that the gene 07E12 had 99% identity with the corresponding sequences of the A. suum whole genome shotgun sequence containing the homologous sequences with conserved sequences of Neuropeptide-Like Protein family member. Likewise, by performing BLASTN and BLASTP searches in the GenBank™, it was shown that this gene had 99 % identity with A. suum cre-nlp-2 protein. CONCLUSION This gene 07E12 which is differentially expressed in the third-stage larvae of A. suum may encode a neuropeptide-like protein family member, a very important molecule in the process of infecting a host.