Document Type : Primary Research paper
Biology dept. - Collage of science - University of Thi-Qar. Iraq
Collage of Nursing - University of Thi-Qar . Iraq
Collage of medicine - University of Thi-Qar . Iraq
is well known that many bacterial species exhibit noticeable genetic variations as a result of the differences in the clinical sources from which they were isolated. Within these bacterial species, Salmonella enterica serovar Typhi represents crucial bacterial organisms that can be used to adapt to the differences of the clinical sources by altering the genetic sequences of BapA (biofilm-associated protein A) locus. This study was conducted to identify the genetic polymorphisms Salmonella enterica serovar Typhi that were isolated from the gallbladder in Al-Nasiryia city. hospitals of. A genetic fragment of 651 bp length that partially covered a coding portion of the BapA gene within twenty-six bacterial samples (assigned S1 to S26) was amplified in this study. A direct sequencing strategy was performed for the observed PCR amplicons in the amplified genetic locus. Subsequently, a comprehensive phylogenetic tree was constructed in the observed variants to assess the accurate phylogenetic distances alongside other relative bacterial sequences. Our results indicated the presence of about 99% homology between our investigated samples with S. Typhi sequences. Six genetic variations were identified in this study, C114A, G173A, A190G, C209A, C210A, and C252T. These variations were variably distributed in the majority of the investigated samples. Meanwhile, S18 had not exhibited any detectable variation. According to this observation, the investigated bacterial samples were positioned in a particular phylogenetic position within the phylogenetic clade of this species in the currently generated comprehensive tree. It was shown that the investigated S. Typhi isolates having these variations were positioned into several adjacent phylogenetic clades, while S18 was taken another adjacent phylogenetic position in the same tree. Based on these identified BapA variations, S18 was positioned in the vicinity to multi-national strains of S. Typhi, while the other variations in the other samples were slightly tilted from the wild S18. Therefore, the utilization of PCR-sequencing strategy in all analyzed bacterial isolates has presented confirmed the presence of multiple sources of these isolates and showed a distinct pattern of their phylogenetic distribution within the S. Typhi sequences. In this study, the majority of identified variations have a missense effect on the BapA protein, which may suggest various degrees of sensitivity to the host immunity interaction. This observation may imply potential adaptation of the analyzed BapA locus to the host immunity. Thus, the majority of investigated isolates have different forms of biologically altered BapA protein, which may show considerable alteration to innate host immunity.