چکیده (انگلیسی):

Background: Toll like receptor (TLR) plays a critical role in recognition and activation
of both innate and adaptive immune responses against microbial pathogens. Several studies have
implicated the genetic variations (polymorphisms) in TLR genes to influence the host susceptibility
to infectious diseases. However, the available literature on TLR polymorphism and susceptibility to
typhoid fever is unclear.
Aim: This study aimed to investigate the polymorphism of TLRs 1, 2, 4 and 5 in typhoid patients
and convalescent phase asymptomatic typhoid carriers among the schoolchildren.
Subjects and methods: TLR genes were amplified by PCR from peripheral blood leukocytes of
schoolchildren with typhoid (n=20) or asymptomatic typhoid carrier (n= 30) state, and normal
healthy individuals (n=50). The RFLP analyses for TLR1, 2, 4 and 5 genes using restriction
enzymes such as AluI, AciI, NcoI and DdeI, respectively, were performed to determine the single
nucleotide polymorphism.
Results: TLR1 polymorphism was observed in 5% (1/20) of typhoid patients and 6.6% (2/30) of
typhoid carriers. TLR2 polymorphism was observed in 10% (2/20) of typhoid patients and 6.6%
(2/30) of carriers. TLR4 polymorphism was not observed in typhoid patients, but 6.6% (2/30) of
typhoid carriers exhibited a polymorphism. As well, TLR5 polymorphism was not observed in
typhoid patients, while 13.3% (4/30) of typhoid carriers had polymorphism. None of the control
healthy individuals had evidence for TLR polymorphisms.
Conclusion: The study reports polymorphisms of TLR genes in a lower proportion among the
schoolchildren with typhoid or convalescent typhoid carrier state.

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