Background
With the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses.
Results
Conductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection of WSSV over a wide linear range of concentration from 1.45 × 102 to 1.45 × 105 DNA copies/ml, with a detection limit as low as 48.4 DNA copies/ml.
Conclusion
The engineered sensor electrode can retain the detection activity up to 5 weeks, to confirm its long-term stability, required for disposable sensing applications. This is the first demonstration of the detection of WSSV by a nanofabricated sensing electrode with high sensitivity, selectivity, and stability, providing as a potential diagnostic tool to monitor WSSV in the aquaculture industry.
Nucleic acids are the blueprint of life. They are not only the construction plan of the single cell or higher associations of them, but also necessary for function, communication and regulation. Due to the pandemic, the attention shifted in particular to their therapeutic potential as a vaccine. As pharmaceutical oligonucleotides are unique in terms of their stability and application, special delivery systems were also considered. Oligonucleotide production systems can vary and depend on the feasibility, availability, price and intended application. To achieve good purity, reliable results and match the strict specifications in the pharmaceutical industry, the separation of oligonucleotides is always essential. Besides the separation required for production, additional and specifically different separation techniques are needed for analysis to determine if the product complies with the designated specifications. After a short introduction to ribonucleic acids (RNAs), messenger RNA vaccines, and their production and delivery systems, an overview regarding separation techniques will be provided. This not only emphasises electrophoretic separations but also includes spin columns, extractions, precipitations, magnetic nanoparticles and several chromatographic separation principles, such as ion exchange chromatography, ion-pair reversed-phase, size exclusion and affinity.
Purification of recombinant proteins is often a challenging matter because high purity and high recovery are desired. If the expressed recombinant protein is also in a complex matrix, such as from the silkworm expression system, purification becomes more challenging. Even if purification from the silkworm expression system is troublesome, it benefits from a high capacity for the production of recombinant proteins. In this study, magnetic nanoparticles (MNPs) were investigated as a suitable tool for the purification of proteins from the complex matrix of the silkworm fat body. The MNPs were modified with nickel so that they have an affinity for His-tagged proteins, as the MNP purification protocol itself does not need special equipment except for a magnet. Among the three different kinds of investigated MNPs, MNPs with sizes of 100 nm to 200 nm and approximately 20 nm-thick nickel shells were the most suitable for our purpose. With them, the total protein amount was reduced by up to at least approximately 77.7%, with a protein recovery of around 50.8% from the silkworm fat body. The minimum binding capacity was estimated to be 83.3 µg protein/mg MNP. Therefore, these MNPs are a promising tool as a purification pretreatment of complex sample matrices.
White spot syndrome virus (WSSV) is one of the most devastating pathogens in penaeid shrimp and can cause massive damage in shrimp aquaculture industries. Previously, the WSSV structural protein VP15 was identified as an antigenic reagent against WSSV infections. In this study, we truncated this protein into VP15(1–25), VP15(26–57), VP15(58–80), and VP15(1–25,58–80). The purified proteins from the E. coli expression system were assayed as potential protective agents in Kuruma shrimp (Marsupenaeus japonicus) using the prime-and-boost strategy. Among the four truncated constructs, VP15(26–57) provided a significant improvement in the shrimp survival rate after 20 days of viral infection. Subsequently, four peptides (KR11, SR11, SK10, and KK13) from VP15(26–57) were synthesized and applied in an in vivo assay. Our results showed that SR11 could significantly enhance the shrimp survival rate, as determined from the accumulated survival rate. Moreover, a multiligand binding protein with a role in the host immune response and a possible VP15-binding partner, MjgC1qR, from the host M. japonicus were employed to test its binding with the VP15 protein. GST pull-down assays revealed that MjgC1qR binds with VP15, VP15(26–57), and SR11. Taken together, we conclude that SR11 is a determinant antigenic peptide of VP15 conferring antiviral activity against WSSV.
Genetic fusion and chemical conjugation
are the most
common approaches
for displaying a foreign protein on the surface of virus-like particles
(VLPs); however, these methods may negatively affect the formation
and stability of VLPs. Here, we aimed to develop a modular display
platform for protein decoration on norovirus-like particles (NoV-LPs)
by combining the NoV-LP scaffold with the SpyTag/SpyCatcher bioconjugation
system, as the NoV-LP is an attractive protein nanoparticle to carry
foreign proteins for various applications. The SpyTagged-NoV-LPs were
prepared by introducing SpyTag peptide into the C-terminus of the
norovirus VP1 protein. To increase surface exposure of the SpyTag
peptide on the NoV-LPs, two or three repeated extension linkers (EAAAK)
were inserted between the SpyTag peptide and VP1 protein. Fluorescence
proteins, EGFP and mCherry, were fused to SpyCatcher and employed
as SpyTag conjugation partners. These VP1-SpyTag variants and SpyCatcher-fused
EGFP and mCherry were separately expressed in silkworm fat bodies
and purified. This study reveals that adding an extension linker did
not disrupt the VLP formation; instead, it increased the particle
size by 4–6 nm. The conjugation efficiency of the VP1-SpyTag
variants with the extended linker improved from ∼15–35
to ∼50–63% based on the densitometric analysis, while
it was up to 77% based on an optical quantification of EGFP and mCherry.
Results indicate that the linker causes the SpyTag peptides to be
positioned further away from the C-termini of VP1 and potentially
increases the exposure of the SpyTag to the outer surface of the NoV-LPs,
allowing more SpyTag/SpyCatcher complex formation on the VLP surface.
Our study provides a strategy for enhancing the conjugation efficiency
of NoV-LP and demonstrates the platform’s utility for developing
vaccines or functional nanoparticles.
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