Chlamydia pneumoniae is an important pathogen which is etiologic agent of acute and chronic infection. The diagnosis of chlamydial infection is based on serology. Current gold standard of diagnosis is MIF(microimmunoflurescence), but it is subjective and time-consuming. Recently, protein microarray using SPR(surface plasmon resonance) sensor is suggested to be a method for detection of infection. For development of protein chip for diagnosis of chlamydial infection, we investigated the morphology of surface with AFM(atomic force microscopy) on gold chip and detected interaction between antibody for Chlamydia pneumoniae and EB(elementary body) immobilized on surface by wavelength shift using SPR sensor.
For surface antigen, EBs of Chlamydia pneumoniae LKK1 were purified after they were grown in Hep-2 cells. For chip surface, gold arrays on glass slides were prepared and cleaned with NH4OH/H2O2/H2O at 80°C for 10 min. Charged arrays were prepared by PDDA(polydiallyldimethylammonium chloride) which has a positive charge and PSS(poly(sodium 4-styrenesulfonate) which has negative charge. After immobilization of chlamydial EB on PDDA surface and PSS surface, we investigated the surface using atomic force microscopy. After immobilization of EB of Chlamydia pneumoniae on surface, antibody for Chlamydia was applied on chip. We monitored the SPR wavelength-shift to detect antigen-antibody interaction using self-assembled SPR sensor.
The chlamydial EBs on positively charged PDDA were visible on surface by atomic force microscopy but EBs on PSS surface were not detected. SPR wavelength increased after interaction of antibody for Chlamydia pneumoniae with EBs immobilized on charged gold surface. The wavelength-shift was correlated with concentration of antigens.
We identified surface immobilization of EBs on gold surface with charged arrays and antigen-antibody interaction on gold chip. More researches are needed to apply to clinical implication.
It may possible that protein chip would be used to diagnosis the atypical pneumonia using SPR sensor.
Woo Kim, None.