Analysis of TLR polymorphisms in typhoid patients and asymptomatic typhoid carriers among the schoolchildren

Abstract

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.