Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/10/2003
Publication Date: 7/20/2003
Citation: Sreekumar, C., Hill, D.E., Fournet, V.M., Rosenthal, B.M., Lindsay, D.S., Dubey, J.P. 2003. Detection of hammondia heydorni-like organisms and their differentiation from Neospora caninum using RAPD-PCR. Journal of Parasitology. 89:1082-1085. Interpretive Summary: Neospora caninum is a single-celled parasite of livestock and companion animals. It causes abortion in livestock and paralysis in dogs. Dogs are the only reservoir hosts for this parasite because they pass a resistant stage (oocyst) in their feces. Differentiation of N. caninum oocysts is a problem. Scientists at Beltsville Agriculture Research Center and Virginia Tech, Blacksburg, Virginia, have developed a method to distinguish N. caninum oocysts from a related parasite, Hammondia heydorni. These results will be of interest to parasitologists, biologists and veterinarians.
Technical Abstract: Neospora caninum and Hammondia heydorni are morphologically and phylogenetically related coccidians that are found in dogs. New diagnostic genetic loci, based on random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR), were developed to aid in the detection of H. heydorni-like parasites and to discriminate them from N. caninum and other related coccidians of dogs. Based on the data obtained from 5 random decamers, H. heydorni (Manhattan-1) and N. caninum (NC1) were characterized by distinct banding patterns (similarity index = 0.068). High stringency PCR assays were developed from the sequences of 2 cloned bands (Genbank accession numbers BZ592549 and BZ592593), uniquely amplified from H. heydorni. Interestingly, using these primers, PCR amplification was achieved only from 2 of the 5 isolates presumed to represent H. heydorni. The same result was obtained from these 5 isolates using a recently described PCR assay directed to the H. heydorni internal transcribed spacer (ITS)-1. It is concluded that H. heydorni and N. caninum are genetically distinct and that such tools may be useful for more detailed characterization of the diversity of related parasites occurring in dogs.