Characterisation of polymorphic DNA and its application to typing of Entamoeba histolytica and Entamoeba dispar
Zaki, Mehreen;
(2002)
Characterisation of polymorphic DNA and its application to typing of Entamoeba histolytica and Entamoeba dispar.
PhD thesis, London School of Hygiene & Tropical Medicine.
DOI: https://doi.org/10.17037/PUBS.00682254
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A key question in amoebiasis is whether
the
variable
symptoms
of amoebic
infections
are a reflection of different strains of
E. histolytica.
To
address
this, tools that
allow
typing of E. histolytica isolates are needed and this
objective
formed the
basis
of
the
present study. A method for PCR-based DNA typing
of
E. histolytica isolates has
been developed using multiple loci with
internal
short tandem
repeats
(STRs)
as
the
polymorphic markers. It has been shown that
E. dispar isolates
can also
be typed
by
this approach and species-specific primers
have
been
developed for two loci.
E. histolytica and E. dispar samples
from
a
wide
geographic
range
were studied to
validate the general utility of these loci.
Results
revealed that
E. histolytica is
genetically highly variable. This was evident
in
all
the
communities
studied.
E. dispar
also displays intra-species variation.
The
patterns
seen
for individual
strains
of
both
species were stable over time in the same
infection. With few
exceptions
a single
E. histolytica or E. dispar strain was identified in
samples
from infected family
groups
and outbreaks. Our results show both the
existence
of mixed
species
infection
as
well
as the possibility of co-infection with
different
strains
of
the
same
species.