Differentiation of Schistosomes by Species, Strain, and Sex by Using Cloned Dna Markers

Proc. Nati. Acad. Sci. USA

Vol. 81, pp. 889-893, February 1984

Medical Sciences

Differentiation of schistosomes by species, strain, and sex by using

cloned DNA markers

(parasitic trematodes/speciation/ribosomal genes)

THOMAS F. MCCUTCHAN*, ANDREW J. G. SIMPSON*, JUDITH A. MULLINS*, ALAN SHER*,

THEODORE E. NASH*, FRED LEWISt, AND CHARLES RICHARDSt

*Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20205; and tBiomedical

Research Institute, 12111 Parklawn Drive, Rockville, MD 20852

Communicated by Richard M. Krause, September 15, 1983

ABSTRACT

We have detected species, strain, and sexspecific genetic markers for the genus Schistosoma by Southern blot analysis of its DNA using cloned DNA segments of the

Schistosoma mansoni ribosomal gene as probes. Restriction

analysis of DNA from eight different strains of S. mansoni,

from Africa and the Caribbean, revealed that the predominant

or major DNA fragment containing the ribosomal gene unit

was the same in each but that low copy number or minor fragments containing the gene varied. It was shown that the detection of these minor fragments could serve as the basis for both

strain differentiation and the analysis of individual differences

within a strain. Analysis of the parents and progeny of a genetic cross revealed sex-linked markers and suggested that these

markers are inherited in a Mendelian fashion. DNAs from the

species Schistosoma haematobium and Schistosoma japonicum

were also analyzed. Differences in the length of the major repeating unit of the ribosomal gene served to distinguish each

species. Furthermore, an array of minor bands was detected in

each species, suggesting that strains of S. haematobium and S.

japonicum could be differentiated in the same manner as S.

mansoni strains.

Schistosomes are parasitic trematodes and are a major cause

of human disease in parts of Africa, Asia, South America,...