Work with LifeSpan to design a custom immunohistochemistry to address your specific biological question. Outsource the entire localization process without having to worry about finding and characterizing target specific antibodies, sourcing and validating difficult-to-find tissues, and having the ability to interpret the resulting immunostaining in relation to complex human pathologies.TCR Screening Services
Test your therapeutic antibodies in immunohistochemistry against a broad panel of normal frozen human tissue types in order to determine potential unintended binding. Our non-GLP TCR services are designed on the FDA recommendation outlined in their "Points to Consider in the Manufacture and Testing of Monoclonal Antibody Products for Human Use".
In response to the global COVID-19 pandemic, LSBio offers the following SARS-CoV-2 specific detection kits and research reagents.
Real-Time qPCR is a technique that allows researchers to quantitatively detect the presence of specific RNA, such as that of SARS-CoV-2, within a sample. Following reverse transcription of RNA to DNA, the polymerase chain reaction is used to amplify the target DNA using fluorescently labeled highly-specific primers. As the reaction progresses, the fluorescence can be monitored, providing a means of quantifying the target. In response to the COVID-19 pandemic, SARS-CoV-2 specific primers have been designed so that the following Real-Time qPCR kits can be made available.
Lateral Flow tests are commonly used for the detection of analytes that are predictive for specific conditions. Pregnancy tests are a common example of Lateral Flow tests. Pathogen-specific IgG and IgM antibodies are commonly used as markers of infection. IgM is predictive of acute infection because it is the first antibody type produced during an immune response. Over time, IgM levels decline and IgM is replaced by IgG, an indicator of prolonged or past infection. Lateral Flow kits are beneficial because they are fast and don’t require specialized equipment.
In response to the COVID-19 pandemic, the global scientific community has accelerated its research to better understand SARS-CoV-2. To support this effort, LSBio offers SARS-CoV-2-specific research reagents, including viral gene cDNAs, recombinant forms of viral proteins, and antibodies for viral detection.
The spike (S) protein is responsible for attachment to and fusion with the host cell. For both SARS-CoV and SARS-CoV-2, the host receptor is known to be angiotensin converting enzyme 2 (ACE2) (Hoffman, 2020). The spike protein is proteolytically cleaved into two subunits, S1 and S2. The S1 subunit binds to ACE2 presented on the host cell surface, and the S2 subunit is responsible for fusion with the host cell. Target cells include pneumocytes and macrophages expressing ACE2 in the lung, as well as ACE2-positive epithelial cells in the lung, gastrointestinal tract, and liver (cholangiocytes) (Xiaoqiang, 2020). The spike protein subunits are of interest as targets of vaccines; the S2 subunit is highly conserved and may be an effective pan-coronavirus target. SARS-CoV studies in monkeys immunized with full-length Spike protein showed successful protection against subsequent infection (Shang, 2020).
The envelope (E) protein is the smallest of the SARS-CoV-2 structural proteins, and it is incorporated into the virion envelope, but this represents only a small amount of total expressed envelope protein. A high proportion is also expressed inside the infected cell, where it is involved in viral assembly, budding, maturation, and propagation (Schoeman,2019; Chang, 2020).
The membrane (M) protein determines the shape of the SARS-CoV-2 viral envelope and organizes viral assembly through interaction with each additional structural protein. (Chang, 2014).
The nucleocapsid (N) protein expressed by SARS-CoV-2 binds to the viral genome and is responsible for packaging it into the ribonucleoprotein complex (capsid).
The ORF3a protein expressed by SARS-CoV-2 has 72% sequence homology with SARS-CoV ORF3a. In SARS-CoV, the ORF3a protein activates NF-κB and the NLRP3 inflammasome by inducing TRAF3-dependent ubiquitination of p105 and ASC (Kam-Leung Siu, 2019). There is evidence that the SARS-CoV-2 virus is less effective in activating the NLRP3 inflammasome and in suppressing the antiviral response when compared to SARS-CoV. More studies are needed to fully understand how the SARS-CoV-2 ORF3a protein influences the immune and inflammatory response as it pertains to COVID-19 disease progression (Yuen, 2020; Zeng, 2004).
NSP12 RNA-dependent RNA polymerase (RdRP, RDR, RNA replicase) is an enzyme that catalyzes the replication of RNA from an RNA template. RdRp is a crucial viral enzyme in the life cycle of RNA viruses. In all positive-strand RNA viruses, including SARS-CoV and SARS-CoV-2, RdRP constitutes the central catalytic subunit of the machinery involved in RNA synthesis and catalyzes the replication and transcription of the RNA genome (te Velthuis, 2010).
There are two types of proteases expressed by SARS-CoV and SARS-CoV-2, the papain-like protease (PLpro, NSP3), and the CL-like protease (NSP5A & B, 3CLpro, Mpro). These proteases are responsible for cleaving the viral polyprotein and releasing nonstructural proteins (NSPs). These NSPs are vital for SARS-CoV-2 viral replication, maturation, and its overall life-cycle. In SARS-CoV, the papain-like protease (PLpro) inhibits type I interferon (IFN) by blocking IRF3 phosphorylation, which results in downstream inhibition of interferon induction and a reduction in the host’s innate immune response. This is thought to contribute to higher viral titer and leads to an increase in cell death and damage to infected and surrounding tissue (Matthews, 2014). The SARS-CoV-2 papain-like protease is thus of interest as a drug target to prevent viral replication and potentially reduce tissue damage (Báez-Santos, 2015)
These represent the major host proteins that are thought to be involved with SARS-CoV-2 infection and COVID-19 disease progression.
Angiotensin-Converting Enzyme 2 (ACE2) is a transmembrane protein found in the lungs, intestines, heart, kidney, liver, and arteries that plays a central role in vascular, renal, and myocardial physiology. The normal function of ACE2 is to convert the inactive vasoconstrictor angiotensin I (AngI) to Ang1-9 and the active form AngII to Ang1-7. It is involved in controlling vascular function, including blood pressure. Absence of ACE2 expression in ace2-/ace2- mice leads to severely reduced cardiac contractility, indicating its importance in regulating heart function (Tikellis, 2012). ACE2 is also the primary attachment receptor for HCoV-N63, SARS-CoV, and SARS-CoV-2 (Zhou, 2020). The S1 portion of the coronavirus spike protein attaches to ACE2 presented on the host cell surface. SARS-CoV-2 targets pneumocytes and macrophages expressing ACE2 in the lung, and it is believed to infect ACE2-positive cells in other tissues, including the gastrointestinal tract and liver (cholangiocytes) (Wrap, 2020; Xiaoqiang, 2020; Hoffman, 2020).
Furin is a proprotein convertase that processes precursor proteins into active products. It has been found to activate the envelope glycoproteins of a variety of viruses and enhances membrane fusion and infectivity. A polybasic furin cleavage site has been discovered in the SARS-CoV-2 spike protein, and it is postulated that this may lead to greater pathogenicity by allowing for cleavage by furin-like enzymes. Furin displays high expression in the lungs, and it is possible that this is exploited by SARS-CoV-2 for spike protein activation. This has been shown for other coronaviruses with furin-like cleavage sites (Coutard, 2020).
TACE is a membrane-bound metalloprotease-disintegrin in the ADAM family of proteins. TACE processes cell surface proteins such as TNF alpha, a proinflammatory cytokine that contributes to a variety of inflammatory disease responses and programmed cell death, as well as ACE2, the receptor that binds SARS-CoV and SARS-CoV-2. TACE was found to be required for SARS-CoV viral entry, and it is of interest as an inhibition target using compounds like TAPI-2 to prevent SARS-CoV and SARS-CoV-2 viral entry (Fu Y., 2020; Lambert, 2005).
Transmembrane protease, serine 2 (TMPRSS2) is required for priming of the both the SARS-CoV and SARS-CoV-2 virus spike proteins prior to entry into the host cell. Viral membrane fusion to the host cell surface requires the cleavage of the spike protein at the S1/S2 and S2’ sites, and TMPRSS2 expression greatly promotes fusion and replication of these viruses in vitro and in vivo. TMPRSS2 may be a useful antiviral drug target, since inhibition of TMPRSS2 with camostat mesylate was found to suppress SARS-CoV-2 infection of lung cells (Matsuyama S, 2020; Hoffmann, 2020).
IRF3 is a core transcriptional regulator of type I IFN-dependent immune responses. It plays a vital role in the innate immune response against both DNA and RNA viruses. IRF3 has been found to be involved with SARS disease progression, as the SARS-CoV viral papain-like protease (PLpro) inhibits type I interferon (IFN) by blocking IRF3 phosphorylation. This leads to downstream inhibition of interferon induction and reduces the host’s innate immune response to the infection (Kopecky-Bromberg, 2007). This is thought to contribute to higher viral titer and lead to an increase in cell death and damage to infected and surrounding tissue (Matthews, 2014).
Cathepsin L (CTSL) is a lysosomal cysteine proteinase involved in intracellular protein catabolism. Its substrates include collagen and elastin, as well as alpha-1 protease inhibitor, a major controlling element of neutrophil elastase activity. Cathepsin L has been found to be crucial for SARS-CoV viral entry into host cells, and recent data suggest that SARS-CoV-2 also depends on CTSL for spike protein priming prior to entry. Inhibiting CTSL was found to significantly reduce SARS-CoV-2 viral entry in 293/hACE2 cells (Hoffmann, 2020; Ou 2020).
LSBio offers a range of research-use-only biochemicals which have potential inhibitory action against SARS-CoV-2 infection.Explore Disease Inhibitors