Novel protein microarray for the detection of avian influenza virus antibodies and simultaneous distinction of antibodies against H5 and H7 subtypes

Multiplex gradient immunochip for detection of post-vaccinal antibodies in poultry

Multiplex analysis as an immunochip-in-a well format for simultaneous detection of post-vaccinal antibodies to three poultry infections (Newcastle disease, infectious bronchitis and bursal disease) in one chicken sera was developed. The immunochip had a microarray format printed on the bottom of a standard microtiter plate well and consisted of 36 microspots (d = 400 μm each) with three lines of viral antigens absorbed in a gradient of five decreasing concentrations. Optimization of assay conditions revealed the necessity of careful choice of the reaction buffer due to the high tendency of chicken IgY to exhibit unspecific binding. The best results were obtained for PBS buffer (pH 6.0) supplied with 0.1% Tween 20. Assay results were visualized by a number of coloured microspots that were correlated with the specific antibody titre in the analysed serum. High (> 8000), medium (3000-8000) or low (1000-3000) antibody titre level for each of three infections could be quickly assessed in one probe visually or with the help of smartphone. ELISA results (antibody titres) and visual gradient immunochip results interpretation (high, medium, low antibody level/titre) for 63 chicken sera with multiple levels of post-vaccinal antibodies against Newcastle disease, infectious bronchitis and bursal disease were in good correlation.

The development of droplet-based microfluidic virus detection technology for human infectious diseases

Virus-based human infectious diseases have a significant negative impact on people's health and social development. The need for quick, accurate, and early viral infection detection in preventive medicine is expanding. A microfluidic control is particularly suitable for point-of-care-testing virus diagnosis due to its advantages of low sample consumption, quick detection speed, simple operation, multi-functional integration, small size, and easy portability. It is also thought to have significant development potential and a wide range of application prospects in the research on virus detection technology. In an effort to aid researchers in creating novel microfluidic tools for virus detection, this review highlights recent developments of droplet-based microfluidics in virus detection research and also discusses the challenges and opportunities for rapid virus detection.

Development of a recombinase-aided amplification combined with a lateral flow dipstick assay for rapid detection of H7 subtype avian influenza virus

Avian influenza viruses (AIV) pose a significant persistent threat to the public health and safety. It is estimated that there have been over 100 outbreaks caused by various H7 subtypes of avian influenza viruses (AIV-H7) worldwide, resulting in over 33 million deaths of poultry. In this study, we developed a recombinase-aided amplification combined with a lateral flow dipstick assay for the detection of hemagglutinin (HA) genes to provide technical support for rapid clinical detection of AIV-H7. The results showed that the assay can complete the reaction within 30 min at a temperature of 39°C. Specificity tests demonstrated that there was no cross-reactivity with other common poultry pathogens, including Newcastle disease virus (NDV) and infections bronchitis virus (IBV). The detection limit of this assay was 1 × 101 copies/μL, while RT-qPCR method was 1 × 101 copies/μL, and RT-PCR was 1 × 102 copies/μL. The κ value of the RT-RAA-LFD and RT-PCR assay in 132 avian clinical samples was 0.9169 (p < 0.001). These results indicated that the developed RT-RAA-LFD assay had good specificity, sensitivity, stability and repeatability and may be used for rapid detection of AIV-H7 in clinical diagnosis.

Development and application of a novel triplex protein microarray method for rapid detection of antibodies against avian influenza virus, Newcastle disease virus, and avian infectious bronchitis virus

Avian influenza virus (AIV), Newcastle disease virus (NDV), and avian infectious bronchitis virus (IBV) inflict immense damage on the global poultry industry annually. Serological diagnostic methods are fundamental for the effective control and prevention of outbreaks caused by these viruses. In this study, a novel triplex protein microarray assay was developed and validated for the rapid and simultaneous visualized detection of antibodies against AIV, NDV, and IBV in chicken sera. The AIV nuclear protein (NP), NDV phosphoprotein (P), and IBV nonstructural protein 5 (nsp5) were produced in a prokaryotic expression system, purified, and immobilized onto an initiator integrated poly(dimethylsiloxane) (iPDMS) film as probes to detect antibodies against these viruses in chicken sera. After optimization of the reaction conditions, no cross-reactivity was detected with infectious bursal disease virus, avian leukosis virus subgroup J and chicken anemia virus antisera. The lowest detectable antibody titers in this assay corresponded to hemagglutination inhibition (HI) titers of 2⁴ and 2¹ for AIV and NDV, respectively, and to an IDEXX antibody titer of 10³ for IBV, using the HI assay and IDEXX commercial ELISA kit as the reference methods. When156 serum samples were tested using the new assay, the HI test and the IBV IDEXX ELISA kit, the assay showed 96.8% (151/156), 97.4% (152/156) and 99.4% (155/156) diagnostic accuracy for detection of AIV, NDV and IBV antibody, respectively. The current study suggests that the newly developed triplex microarray is rapid, sensitive, and specific, providing a viable alternative assay for AIV, NDV, and IBV antibody screening in epidemiological investigations and vaccination evaluations.

Development and evaluation of a monoclonal antibody-based competitive ELISA for the detection of antibodies against H7 avian influenza virus

BACKGROUND

H7 subtype avian influenza has caused great concern in the global poultry industry and public health. The conventional serological subtype-specific diagnostics is implemented by hemagglutination inhibition (HI) assay despite lengthy operation time. In this study, an efficient, rapid and high-throughput competitive enzyme-linked immunosorbent assay (cELISA) was developed for detection of antibodies against H7 avian influenza virus (AIV) based on a novel monoclonal antibody specific to the hemagglutinin (HA) protein of H7 AIV.

RESULTS

The reaction parameters including antigen coating concentration, monoclonal antibody concentration and serum dilution ratio were optimized for H7 antibody detection. The specificity of the cELISA was tested using antisera against H1 ~ H9, H11 ~ H14 AIVs and other avian viruses. The selected cut-off values of inhibition rates for chicken, duck and peacock sera were 30.11, 26.85 and 45.66% by receiver-operating characteristic (ROC) curve analysis, respectively. With HI test as the reference method, the minimum detection limits for chicken, duck and peacock positive serum reached 20, 21 and 2- 1 HI titer, respectively. Compared to HI test, the diagnostic accuracy reached 100, 98.6, and 99.3% for chicken, duck and peacock by testing a total of 400 clinical serum samples, respectively.

CONCLUSIONS

In summary, the cELISA assay developed in this study provided a reliable, specific, sensitive and species-independent serological technique for rapid detection of H7 antibody, which was applicable for large-scale serological surveillance and vaccination efficacy evaluation programs.