Highly sensitive detection of Staphylococcus aureus α-Hemolysin protein (Hla or α-toxin) by Apta-qPCR

Abstract α-toxin of Staphylococcus aureus is belonging to pore-forming toxins (PFTs) which can lyse red and white blood cells except neutrophils. In addition to existence of the hla gene in the majority of S. aureus strains (about 95%), higher expression exert enhanced pathogenicity to the bacteria. Various methods such as aptamer-based ones could serve for detection of the toxin. In the current study, an apta-qPCR assay is developed based on the murine polyclonal antibodies and a specific aptamer to detect wide range of α-toxin amounts. A recombinant α-toxin was administered to mice in denature form to trigger specific antibodies. The specific antibodies were purified from immune sera. These antibodies served as capture where an aptamer employed as detector in the designed apta-qPCR assay. The results showed that spiked α-toxin in the sera samples was detected alpha toxin between 300 to 0.5 ng/mL with no cross reactivity. The coefficient of variation (CV) percent of intra- and inter assays were 0.84 and 1.06 respectively. Since in apta-qPCR assay, combination of specific polyclonal antibodies as capture, and specific aptamer along with real-time PCR (qPCR) sensitivity is employed, this robust method could be used in diagnostic laboratories to detect various levels of the toxin in human sera samples.