Novel chip-based isoelectric focusing device for fractionation of bacteria prior to their mass spectrometry identification.

We have developed a planar chip utilizing divergent geometry of separation channel capable of vertical free-flow electrophoresis of particles at flows of lower hundreds of microliters per minute. The divergent flow isoelectric focusing (DF-IEF) chip consists of two sheets of clear polystyrene glass which serve as a base with working channels and a top cover sealing the separation channel. Optimization showed that the chip is capable to form pH gradient within 1 h and separation is completed in 5 or more minutes depending on the sample volume. The vertical position of the chip enabled analysis of sedimenting particles including microorganisms. Four different common bacteria species inactivated with H2O2 vapors were analyzed in a series of experiments. Isoelectric points were determined with capillary isoelectric focusing with following fractionation using DF-IEF with intact cell matrix-assisted laser desorption/ionization mass spectrometry detection. The DF-IEF chip fractionation proved promising for bacterial sample preparation from complex matrices for subsequent identification of whole cells by mass spectrometry.

Rapid separation and identification of the subtypes of swine and equine influenza A viruses by electromigration techniques with UV and fluorometric detection.

Influenza A is viral disease, which is a cause of yearly epidemics and, potentially, pandemics. The conventional techniques used today are equipment-demanding, time-consuming and laborious. Recently, we have confirmed that the capillary isoelectric focusing is a suitable fast alternative for the verifying of virus purity. In the wide pH gradient of pH range 2.0-7.5 the isoelectric points for subtypes of equine (H3N8) and swine (H1N2) influenza A viruses were determined approximately as 6.6 and 6.5, respectively. In this contribution we have verified these findings using different isolates of different viral subtypes of swine influenza, H1N1, H1N2, and of equine influenza, H3N8, H7N7, which were separated by capillary zone electrophoresis (CZE) and capillary isoelectric focusing (CIEF) in the narrow pH gradient pH range from 6.0 to 7.0. It was found that the isoelectric points of different isolates and subtypes of equine and swine influenza are almost independent of their origin. The electromigration velocities of subtypes of equine or swine influenza viruses were dependent on the antigenic subtypes of their surface glycoproteins. The detection sensitivity of the influenza viruses labeled by the fluorescent non-ionogenic tenside based on poly(ethylene glycol)pyrenebutanoate for fluorometric detection was increased and down to ten labeled viruses were detected. The isoelectric points of the native and labeled equine and swine influenza A viruses and their subtypes do not differ. According to our experiments these methods appear to be useful for the fast preliminary differentiation of influenza viruses in future.

Testing of the influenza virus purification by CIEF.

In virological practice, the pre-concentration, purification and subsequent determination of the purity and concentration of the viruses from the cultural medium and/or from the real sample are required. The conventional techniques used today are equipment demanding, time-consuming and laborious. In this study, the CIEF of influenza viruses with UV detection has been developed and subsequently used to test the purification of the virus from the biological samples. The equine and swine influenza viruses present in infected allantoic fluid of specific pathogen free embryonated chicken eggs were precipitated by using PEG 6000 and sodium chloride. The precipitated viruses were centrifuged at 14 000 x g, and the impurities of different densities were removed by using the sucrose gradients. The efficiency of the virus purification technique was examined by the CIEF and compared to the results of real-time PCR. The pIs of both influenza viruses were determined. Simultaneously, the CIEF was found to be a suitable method for the rapid testing of the efficiency of the virus purification.

Comparison of three template preparation methods for routine detection of beak and feather disease virus and avian polyomavirus with single and nested polymerase chain reaction in clinical specimens.

Direct comparisons are important when assessing the value of DNA extraction methods for diagnostic virology as the inhibitors present and the efficiency of extraction vary with the target infectious agent as well as the species and the site from which the clinical sample was obtained. Three DNA extraction methods were compared for routine polymerase chain reaction (PCR) detection of beak and feather disease virus (BFDV) in whole blood and feather samples and of avian polyomavirus (APV) in feather samples. Boiling in Chelex 100 Resin was found to be the most sensitive method for detection of BFDV or APV DNA in both feather and blood samples. In combination with nested PCR it enabled detection of BFDV DNA in 13/13 positive whole blood samples and in 22/23 positive feather samples. It also enabled detection of APV in 31/31 samples detected as positive in this study. NucleoSpin kits enabled detection of BFDV DNA in only 9/13 blood samples and in 18/23 feather samples. The lower rate of BFDV DNA detection when using NucleoSpin kits was not a result of inhibition of PCR in most cases. The NucleoSpin Tissue Kit enabled detection of APV DNA in 29/31 feather samples. Inhibition of DNA amplification was observed when using the DNAzol Direct kit. Therefore, of the methods evaluated here, Chelex 100 Resin treatment of samples was the best option for routine testing for BFDV and APV DNA in clinical samples.