Dengue virus (DENV) and West Nile virus (WNV) are two well-documented mosquito-borne flaviviruses that cause significant health problems worldwide. Driven by this need, we have developed a bio-conjugated gold nanoparticle (AuNP)-based surface enhanced Raman spectroscopy (SERS) probe for the detection of both DENV and WNV. Reported data demonstrate anti-flavivirus 4G2 antibody conjugated gold nanoparticle (GNP) SERS probe can be used as a Raman fingerprint for the ultrasensitive detection of DENV and WNV selectively. Experimental data show that due to the plasmon coupling in nano-assembly, antibody conjugated GNP- based SERS is able to detect as low as 10 plaque-forming units (PFU)/ml of DENV-2 and WNV, which is comparable with the sensitivity of quantitative PCR-based assays. Selectivity of our probe was demonstrated using another mosquito-borne chikungunya virus (CHIKV) as a negative control. Experimental data demonstrate a huge enhancement of SERS intensity is mainly due to the strong electric field enhancement, which has been confirmed by the finite-difference time-domain (FDTD) simulation. Reported FDTD simulation data indicate the SERS enhancement factor can be more than 104 times, due to the assembled structure. Reported results suggest that bio-conjugated AuNP-4G2 based SERS probes have great potential to be used to screen viral particles in clinical and research-based laboratories.

West Nile virus (WNV) can cause severe human neurological diseases including encephalitis and meningitis. The mechanisms by which WNV enters the central nervous system (CNS) and host-factors that are involved in WNV neuroinvasion are not completely understood. The proinflammatory chemokine osteopontin (OPN) is induced in multiple neuroinflammatory diseases and is responsible for leukocyte recruitment to sites of its expression. In this study, we found that WNV infection induced OPN expression in both human and mouse cells. Interestingly, WNV-infected OPN deficient (Opn −/−) mice exhibited a higher survival rate (70%) than wild type (WT) control mice (30%), suggesting OPN plays a deleterious role in WNV infection. Despite comparable levels of viral load in circulating blood cells and peripheral organs in the two groups, WNV-infected polymorphonuclear neutrophil (PMN) infiltration and viral burden in brain of Opn −/− mice were significantly lower than in WT mice. Importantly, intracerebral administration of recombinant OPN into the brains of Opn −/− mice resulted in increased WNV-infected PMN infiltration and viral burden in the brain, which was coupled to increased mortality. The overall results suggest that OPN facilitates WNV neuroinvasion by recruiting WNV-infected PMNs into the brain.

Zika virus (ZIKV) is a globally emerging mosquito-transmitted flavivirus that can cause severe fetal abnormalities, including microcephaly. As such, highly sensitive, specific, and cost-effective diagnostic methods are urgently needed. Here, we report a novel electrogenerated chemiluminescence (ECL)-based immunoassay for ultrasensitive and specific detection of ZIKV in human biological fluids. We loaded polystyrene beads (PSB) with a large number of ECL labels and conjugated them with anti-ZIKV monoclonal antibodies to generate anti-ZIKV-PSBs. These anti-ZIKV-PSBs efficiently captured ZIKV in solution forming ZIKV-anti-ZIKV-PSB complexes, which were subjected to measurement of ECL intensity after further magnetic beads separation. Our results show that the anti-ZIKV-PSBs can capture as little as 1 PFU of ZIKV in 100 μl of saline, human plasma, or human urine. This platform has the potential for development as a cost-effective, rapid and ultrasensitive assay for the detection of ZIKV and possibly other viruses in clinical diagnosis, epidemiologic and vector surveillance, and laboratory research.

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The analytical performances of a novel DNA-ligand system using the time-resolved fluorescence (TRF) response of ochratoxin A (OTA)-terbium-DNA aptamer interaction were tested for the quantitative determination of OTA in wheat. Wheat was extracted with acetonitrile/water (60:40, v/v) followed by clean-up through affinity columns containing a DNA-aptamer-based oligosorbent. Then, OTA was detected by TRF spectroscopy after reaction with a terbium fluorescent solution containing the DNA-aptamer probe. The entire procedure was performed in less than 30 min, including sample preparation, and allowed analysis of several samples simultaneously with a 96-well microplate reader. The average recovery from samples spiked with 2.5-25 μg kg(-1) OTA was 77%, with a relative standard deviation lower than 6% and a quantification limit of 0.5 μg kg(-1). Comparative analyses of 29 naturally contaminated (up to 14 μg kg(-1)) wheat samples using the aptamer-affinity column/TRF method or the immunoaffinity column/high-performance liquid chromatography method showed good correlation (r = 0.985) in the range tested. The trueness of the aptamer-based method was additionally assessed by analysis of two quality control wheat materials for OTA. The DNA-ligand system is innovative, simple and rapid, and can be used to screen large quantities of samples for OTA contamination at levels below the EU regulatory limit with analytical performances satisfying EU criteria for method acceptability.