Evaluation of wondfo rapid diagnostic kit (Pf-HRP2/PAN-pLDH) for diagnosis of malaria by using nano-gold immunochromatographic assay.

Prompt and accurate diagnosis is necessary to start adequate treatment for different affecting species including P. falciparum and P. vivax. Here we described the Wondfo Rapid diagnostic Kit (Pf-HRP2/PAN-pLDH) for the detection of P. falciparum and pan-plasmodium in patient specimen by using a nano-gold immunochromatographic assay. Our rapid assay adapted nano-gold labeling techniques and the monoclonal antibodies (mAbs) against both histidine rich protein-2 (Pf HRP-2) of P. falciparum and pan plasmodium-specific pLDH (pan pLDH). The established two-antibody sandwich immunochromatographic assay could detect P. falciparum and pan-plasmodium. The sensitivity and specificity of Wondfo rapid diagnostic kit were determined by comparing with the "gold standard" of microscopic examination of blood smears. In this study1023 blood samples were collected from outpatient clinics in China and Burma, and detected by both Wondfo kit and microscopic examination. The detection sensitivity and specificity of Wondfo rapid diagnostic kit were 96.46% and 99.67% for P. falciparum (HRP2), 95.03% and 99.24% for pLDH, 96.83% and 99.74% for non-falciparum species, 96.70% and 99.74% for P. vivax, respectively. These results indicate that Wondfo rapid diagnostic assay may be useful for detecting P. falciparum and non-P. falciparum (especially P.v.) in patient specimen.

Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples.

Evaluation of Wondfo influenza A&B fast test based on immunochromatography assay for rapid diagnosis of influenza A H1N1.

Influenza viruses cause significant morbidity and mortality in both children and adults during local outbreaks or epidemics. Therefore, a rapid test for influenza A&B would be useful. This study was conducted to evaluate the clinical performance of the Wondfo influenza A&B test for rapid diagnosis of influenza A H1N1 Infection. The rapid testing assay could distinguish infection of influenza A and B virus. The reference viral strains were cultured in MDCK cells while TCID50 if the viruses were determined. The analytical sensitivity of the Wondfo kit was 100TCID50/ml. The Wondfo kit did not show cross reactivity with other common viruses. 1928 suspected cases of influenza A (H1N1) virus infection were analyzed in the Wondfo influenza A&B test and other commercially available products. Inconsistent results were further confirmed by virus isolation in cell culture. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 100%, 98.23%, 92.45%, and 100% for flu A, and 96.39%, 99.95%, 98.77%, and 99.84% for flu B respectively. 766 suspected cases of influenza A (H1N1) virus infection were analyzed in the Wondfo influenza A&B test and RT-PCR. The sensitivity, specificity, PPV and NPV were 56.5%, 99.75%, 99.52% and 71.04% for flu A, 25.45%, 99.86%, 93.33% and 94.54% for flu B respectively. These results indicate that the Wondfo influenza A&B test has high positive and negative detection rates. One hundred fifty-six specimens of influenza A (H1N1) confirmed by RT-PCR were analyzed by the Wondfo influenza A&B test and 66.67% were positive while only 18.59% were positive by the reference kit. These results indicate that our rapid diagnostic assay may be useful for analyzing influenza A H1N1 infections in patient specimen.

[Interaction between latex microspheres and antibody proteins revealed by fluorescence spectroscopy].

Latex-antibody complexes were prepared by the method of covalent coupling and the properties of the complexes were studied by fluorescence spectrophotometric method for the purpose of revealing the interaction between latex microspheres and antibody proteins. Analysis of intrinsic fluorescence spectra showed that after being coupled with latex microspheres, the emission maximum of antibody protein showed an obvious blue shift, the intensity of emission maximum decreased significantly, the tertiary structure of antibody protein changed to some extent, the interaction between latex microspheres and antibody proteins had a great quenching effect on the intrinsic fluorescence spectra of antibody proteins, the quenching effect was enhanced along with the increasing pH value and latex concentration, and the quenching mechanism was static quenching. Results of exogenous fluorescence spectra showed that the fluorescence intensity of emission maximum was enhanced significantly after being coupled with latex microspheres, the hydrophobicity of antibody protein was decreasing with the increase in the pH values, however, due to the increasing latex concentration, the hydrophobicity antibody protein was increasing.

[FTIR analysis of the impact of covalent coupling on the secondary structure of antibody protein].

The immunolatex was prepared by covalent coupling. FTIR technology combined with substractive spectroscopy, deconvolution, derivation and curve-fitting methods were used to study the structure of the antibody protein on the immunolatex. The result demonstrates that the alpha-helix strcture of antibody increases with the increase in the pH value and the concentration of latex. So it is concluded that covalent coupling has a great impact on the secondary structure of antibody protein.

Study and evaluation of Wondfo rapid diagnostic kit based on nano-gold immunochromatography assay for diagnosis of Plasmodium falciparum.

Malaria has been recognized as a human disease for thousands of years and remains one of the most common diseases affecting humans worldwide. Therefore, a method for rapidly detecting Plasmodium falciparum is necessary and useful. We have developed Wondfo rapid diagnostic kit based on nano-gold immunochromatography assay for the detection of P. falciparum in patient specimen. In the present study, we demonstrated the sensitivity and specificity of the rapid diagnostic kit in which nano-gold labeling techniques and the monoclonal antibodies against histidine-rich protein-2 of P. falciparum were used to establish two-antibody sandwich immunochromatographic assay for detecting P. falciparum. By using microscopic examination of blood smears as control, the sensitivity, specificity, and feasibility of Wondfo rapid diagnostic kit was determined in the prompt and accurate diagnosis of malaria. In this study, 1,558 blood samples were collected from outpatient clinics in China and detected by both Wondfo kit and microscopic examination. The Wondfo kit did not show cross-reaction with microfilaria, Toxoplasma gondii, and other parasites in the blood. The patient samples positive for rheumatoid factor, HIV, tuberculosis, and syphilis did not show false positivity when testing with Wondfo kit. The detection sensitivity and specificity of Wondfo rapid diagnostic kit were 95.49% and 99.53%, respectively. These results indicate that our rapid diagnostic assay may be useful for detecting P. falciparum in patient specimen.

[Application of ELISA for microcystins detection].

Microcystins (MCs) may be group of closely related toxic cyclic heptapeptides produced by common cyanobacteria (blue-green algae). Their toxicity could be associated with specific inhibition of intracellular protein phosphatases type-1 and type-2A (PP1 and PP2A, respectively). There are some methods for analyzing and detecting MCs in aquatic environment, such as HPLC, LC-MS, PPIA, and ELISA. This review introduces advances on MCs determined by enzyme-linked immunosorbent assay (ELISA), and estimates the prospective development of ELISA for monitoring MCs in natural waters.