Prevalence of Salmonella Pathogenisity Island (SPI1, SPI2, SPI3 and SPI5) Genes in Salmonella species Isolated from fresh Broiler Chicken Meat in Sri Lanka

Abstract

Purpose: Salmonella is a significant pathogen affecting wider range of animals and one of the main causes of diarroeal diseases leading to millions of human cases globally. Pathogenicity islands of Salmonella (SPI) are imperative in invasion of host cell and pathogenesis within the cell. It is found that SPI from 1 to 5 are present in every serovars of S. enterica and these are laterally acquired virulence regions.Research Method: This study investigated the presence of some virulence genes that belong to the SPI1, SPI2, SPI3 and SPI5 within 23 Salmonella isolates from broiler chicken meat in Sri Lanka using PCR method and further some virulence genes (gene encoding the invasion-associated protein, structural gene for attachment and invasion, regulatory gene for invasion and like nucleoid structuring gene) were quantified using RT-PCR. Findings:The study revealed the presence of Pathogenicity Island 1 genes such as hilA, invH, invF, invA and hns in all the isolates. Among the SPI 2 genes investigated, all the isolates of Salmonella showed the presence of ssaO, ssaQ, ssaP and ssaS (genes encoding for T3SS apparatus proteins), sscB and sscA (gene for secretion system chaperon proteins), sseF, sseD (genes coding for secreted effector proteins). In all isolates, SPI 3 genes, responsible in magenisum transport (mgtB and mgtC) were found. The rhuM gene (that supposed to code for a cytoplasmic protein) was absent in four isolates whereas the gene cigR (which predicted as codes for membrane protein) was absent in two isolates. The SPI 5 genes pipB was present in all the isolates except in one isolate whereas sopB was absent in one isolate.Originality/Value: This study found that some SPI genes are conserved in most of the Salmonella isolates from fresh broiler chicken meat in Sri Lanka and the expression of different virulence genes vary with the isolate. This molecular basic will pave the way to explore more on local isolates of Salmonella, detection methods and control methods.