HIV and COVID-19: A Tale of Two Pandemics.

In the last 5 decades, we have witnessed two major pandemics, AIDS caused by the Human Immunodeficiency Virus (HIV) and the CoronaVirus Disease-19 (COVID-19) caused by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). The emergence of COVID-19 has raised many concerns for researchers, doctors, patients, and other institutions associated with HIV. A lot of debate has persisted on clinical outcomes, the use of antiretrovirals, and vaccines on HIV patients infected with COVID-19. This note attempts to present different aspects of HIV and SARS-CoV-2 across themes like SARS-CoV-2 coinfections in people living with HIV, the psychological impact, treatments, vaccination, etc. We highlight how learnings from the COVID-19 pandemic can help us in tackling the HIV pandemic.

Computational design and clinical demonstration of a copper nanocluster based universal immunosensor for sensitive diagnostics.

Nanoparticle based sensors are good alternatives for non-enzymatic sensing applications due to their high stability, superior photoluminescence, biocompatibility and ease of fabrication, with the only disadvantage being the cost of the synthesis process (owing to the expensive precursors and infrastructure). For the first time, we report the design of an immunosensor employing streptavidin conjugated copper nanocluster, developed at a much lower cost compared to other nanomaterials like noble metal nanoparticles and quantum dots. Using in silico tools, we have tried to establish the dynamics of conjugation of nanocluster to the streptavidin protein, based on EDC-NHS coupling. The computational simulations have successfully explained the crucial role played by the components of the immunosensor leading to an efficient design capable of high sensitivity. In order to demonstrate the functioning of the Copper Nanocluster ImmunoSensor (CuNIS), HIV-1 p24 biomarker test was chosen as the model assay. The immunosensor was able to achieve an analytical limit of detection of 23.8 pg mL-1 for HIV-1 p24 with a linear dynamic range of 27-1000 pg mL-1. When tested with clinical plasma samples, CuNIS based p24 assay showed 100% specificity towards HIV-1 p24. With the capability of multiplexed detection and a cost of fabrication 100 times lower than that of the conventional metal nanoclusters, CuNIS has the potential to be an essential low-cost diagnostic tool in resource-limited settings.

Sub-picogram level sensitivity in HIV diagnostics achieved with the europium nanoparticle immunoassay through metal enhanced fluorescence.

We describe a novel application of Metal Enhanced Fluorescence (MEF) to immunoassays for boosting the signal through a single step modification of the europium nanoparticle based immunoassay with addition of gold nanoparticles. The new limit of detection was found to be 0.19 pg mL-1 which was much lower than that of the conventional assay which was around 1.80 pg mL-1, thus achieving a ten-fold increase in the limit of detection of p24, an early biomarker for HIV infections. Real world applications of the new technique were demonstrated with the commercially available Perkin Elmer Alliance kits greatly improving their sensitivity limits, thus demonstrating that the sensitivity and reproducibility of this approach are as good as those of high-end, sensitive immunoassays. The results of this study pave the way for the development of a highly sensitive screening protocol based on any fluorescent nanoparticle based immunoassay.

Cross-Subtype Detection of HIV-1 Capsid p24 Antigen Using a Sensitive Europium Nanoparticle Assay.

Accurate and early detection of diverse HIV-1 subtypes using currently available p24 antigen assays have been a major challenge. We report the development of a sensitive time resolved fluorescence (TRF) europium nanoparticle immuno assay for cross subtype detection of p24 antigen using broadly cross-reactive antibodies. Several antibodies were tested for optimal reactivity with antigens of diverse HIV-1 subtypes and circulating recombinant forms. We tested HIV strains using this assay for sensitivity and quantification ability at the pico-gram per millilter level. We identified two broadly cross-reactive HIV-1 p24 antibodies C65690M and ANT-152, which detected all strains of HIV tested. These two antibodies also yielded a better signal to cutoff ratio for the same amount of antigen tested in comparison to a commercial assay. Using an appropriate combination of C65690M and ANT-152 p24 antibodies capable of detecting all HIV types and highly sensitive TRF-based europium nano particle assay platform, we developed a sensitive p24 antigen assay that can detect HIV infection of all HIV subtypes and may be useful in early detection.

Streptavidin-conjugated gold nanoclusters as ultrasensitive fluorescent sensors for early diagnosis of HIV infection.

We have engineered streptavidin-labeled fluorescent gold nanoclusters to develop a gold nanocluster immunoassay (GNCIA) for the early and sensitive detection of HIV infection. We performed computational simulations on the mechanism of interaction between the nanoclusters and the streptavidin protein via in silico studies and showed that gold nanoclusters enhance the binding to the protein, by enhancing interaction between the Au atoms and the specific active site residues, compared to other metal nanoclusters. We also evaluated the role of glutathione conjugation in binding to gold nanoclusters with streptavidin. As proof of concept, GNCIA achieved a sensitivity limit of detection of HIV-1 p24 antigen in clinical specimens of 5 pg/ml, with a detection range up to1000 pg/ml in a linear dose-dependent manner. GNCIA demonstrated a threefold higher sensitivity and specificity compared to enzyme-linked immunosorbent assay for the detection of HIV p24 antigen. The specificity of the immunoassay was 100% when tested with plasma samples negative for HIV-1 p24 antigen and positive for viruses such as hepatitis B virus, hepatitis C virus, and dengue. GNCIA could be developed into a universal labeling technology using the relevant capture and detector antibodies for the specific detection of antigens of various pathogens in the future.

Application of nanotechnology in biosensors for enhancing pathogen detection.

Rapid detection and identification of pathogenic microorganisms is fundamental to minimizing the spread of infectious disease, and informing clinicians on patient treatment strategies. This need has led to the development of enhanced biosensors that utilize state of the art nanomaterials and nanotechnology, and represent the next generation of diagnostics. A primer on nanoscale biorecognition elements such as, nucleic acids, antibodies, and their synthetic analogs (molecular imprinted polymers), will be presented first. Next the application of various nanotechnologies for biosensor transduction will be discussed, along with the inherent nanoscale phenomenon that leads to their improved performance and capabilities in biosensor systems. A future outlook on characterization and quality assurance, nanotoxicity, and nanomaterial integration into lab-on-a-chip systems will provide the closing thoughts. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > Biosensing.

Femtogram Level Sensitivity achieved by Surface Engineered Silica Nanoparticles in the Early Detection of HIV Infection.

We have engineered streptavidin labelled Europium doped fluorescent silica nanoparticles which significantly increased sensitivity without compromising the specificity of the immunoassay. As a proof of concept, a time resolved fluorescence based sandwich immunoassay was developed to detect HIV-1 p24 antigen in clinical specimens. The detection range of the silica nanoparticle based immunoassay (SNIA) was found to be between 0.02 to 500 pg/mL in a linear dose dependent manner. SNIA offers 1000 fold enhancement over conventional colorimetric ELISA. Testing of plasma samples that were HIV negative showed no false positive results in the detection of HIV-1 p24 antigen. This highly sensitive p24 assay can help improve blood safety by reducing the antibody negative window period in blood donors in resource limited settings where nucleic acid testing is not practical or feasible. This technology can also be easily transferred to a lab-on-a-chip platform for use in resource limited settings and can also be easily adopted for the detection of other antigens.

Aqueous based reflux method for green synthesis of nanostructures: Application in CZTS synthesis.

The aqueous based reflux method useful for the green synthesis of nanostructures is described in detail. In this method, the parameters: the order of addition of precursors, the time of the reflux and the cooling rate should be optimized in order to obtain the desired phase and morphology of the nanostructures. The application of this method is discussed with reference to the synthesis of CZTS nanoparticles which have great potential as an absorber material in the photovoltaic devices. The highlights of this method are:•Simple.•Low cost.•Aqueous based.