Female-specific genomic PCR sequences from Schistosoma mansoni as probes for hybridization histochemistry.

Rapid methods for sexing single larval or egg stages of schistosomes have been difficult to establish. Such methods would be of value for assessing changes in sex ratios at different stages of the life cycle and studying diseases processes of schistosomiasis. We describe the use of hybridization histochemistry for identification of female eggs of Schistosoma mansoni in sections of infected mouse liver using a highly repetitive genomic DNA sequence generated by the polymerase chain reaction with primers spanning a known female-specific sequence (W1) of S. mansoni. In an initial study, approximately half of the eggs in each liver section from mice infected for 50 days labelled heavily with this probe. Further studies will evaluate the sensitivity and specificity of the probe on clonal populations (either male or female) or larvae in host tissue.