The extent of genomic variability of clones of Schistosoma mansoni obtained
from field isolates was compared with that of strains that have been
laboratory maintained. Analysis was undertaken using randomly amplified
polymorphic dNAs (RAPDs) generated with three primers. Phenograms showing
the similarity among the clones were constructed. The data showed that
while the laboratory strain is highly homogeneous the clones derived from
the field populations were highly variable with 43% of RAPDs exhibiting
polymorphisms among 23 clones. Clones isolated from the same infected
individual were always more closely grouped than clones from different
individuals. The data clearly demonstrated that earlier analyses of the
genomic variability in S. mansoni have underestimated this phenomenon due
to the failure to examine field isolates.
