BA-ELISA isolation of cytosolic Salmonella and vacuolar Salmonella

Salmonella is a pathogenic Gram-negative bacterium and important zoonotic pathogen survive in host cell, which is well known to cause gastrointestinal infections and even death in human through food contamination. Salmonella survives and reproduces within cells in two forms of cytosolic Salmonella and vacuolar Salmonella. However, the current researches on the mechanism of Salmonella infection was mostly based on the total numbers, and there is no clear distinction between cytosolic Salmonella and vacuolar Salmonella. This article combined biotin-streptavidin-amplified enzyme-linked immunosorbent assay(BA-ELISA) and Flat colony counting method to separate and quantify cytosolic Salmonella and vacuolar Salmonella. The results showed that the anti-Salmonella antibody with a dilution ratio of 1:500 can bind ~1700 Salmonella, and the binding rate reached to~70%. In terms of bacterial counts, vacuolar Salmonella dominates in the early stage of Salmonella infection, and cytosolic Salmonella dominates in the later stage, the reproduction rate of vacuolar Salmonella is significantly lower than cytosolic Salmonella during Salmonella infection, the dynamic growth curve of cytosolic Salmonella and vacuolar Salmonella intuitively reflected the proliferation status of the two forms of Salmonella during the entire process of Salmonella infection.