CHARACTERIZATION OF OESOPHAGOSTOMUM-BIFURCUM AND NECATOR-AMERICANUS BY PCR-RFLP OF RDNA

Esophagostomiasis in humans due to infection with Oesophagostomum bifu rcum (nodular worm) is of major human health significance in northern Togo and Ghana, where Necator americanus (human hookworm) also exists at high prevalence. Yet, very little is known about the transmission p atterns of O. bifurcum, which is in part due to the difficulties in di agnosis and in differentiating some life-cycle stages of O. bifurcum f rom N. americanus using morphological features. As a first step toward developing a molecular-diagnostic assay, it was evaluated whether rib osomal (r)DNA could provide genetic markers for the identification of O. bifurcum and N. americanus to species. Internal transcribed spacer rDNA (plus flanking and intervening sequences) was analyzed by polymer ase chain reaction-linked restriction fragment length polymorphism (PC R-RFLP) using several restriction endonucleases. The analysis showed t hat there was no detectable intraspecific difference in the size of th e PCR products among multiple samples, that there was a consistent siz e difference in the products (of 110 bp or 350 bp, depending on region amplified) between the species, and that there was no significant var iation in restriction patterns within each species. These results indi cate that the rDNA spanning the internal transcribed spacers provides useful genetic markers for the identification of 0. bifurcum and N. am ericanus to species, which has important implications for developing P CR-based tools to study the epidemiology and population biology of O. bifurcum.