After launching the successful anti-COVID-19 & SARS-CoV S glycoprotein antibody clone CR3022, we are pleased to announce two anti-SARS-CoV-2 nucleoprotein (nucleocapsid) antibodies for COVID-19 research and diagnostics. Our recombinant antibody technology allows us to offer these antibodies in various engineered formats – such as human IgG1, IgG3, IgM and IgA; antibody fragments; and species such as rabbit and mouse – for use as serological controls and evaluation of mono- and combination-therapy potential.
- Anti-Covid-19 & SARS-CoV Nucleoprotein [CR3018 (03-018)] (Ab01690)
- Anti-Covid-19 & SARS-CoV Nucleoprotein [CR3009 (03-009)] (Ab01691)
The SARS-CoV-2 nucleocapsid (N) protein plays a crucial role in viral infection through its involvement in RNA package and virus particle release. The N protein is highly expressed during viral infection and is widely used in vaccine development serological assays. It was demonstrated that COVID-19 patients’ sera contain IgG, IgM and IgA antibodies against the N protein, showing that SARS-CoV-2 nucleoprotein is a potent antigen useful for diagnostics purposes (PMID: 32416961). Furthermore, the crystal structure of the RNA-binding N-terminal fragment of the SARS-CoV-2 nucleocapsid protein has been established, which is especially valuable for anti-COVID-19 therapeutics development.
Competitive ELISA of both anti-nucleocapsid antibodies suggests that they bind different, non-overlapping epitopes of the N protein of SARS-CoV. Thus, a combination of these two antibodies is suggested for virus capture assays. Clone CR3018 (catalog # Ab01690) binds the amino acid residues between 11-19 of the N protein of SARS-CoV, while clone CR3009 (catalog # Ab01691) binds a non-linear/conformational epitope of the N protein of SARS-CoV, both of which are sufficiently conserved to permit binding of these antibodies to SARS-CoV-2.
Figure 1 shows the binding curve of both antibodies in rabbit IgG format to SARS-CoV-2 nucleoproteins, while Figure 2 shows both antibodies being used as positive controls in COVID-19 rapid diagnostic tests, in human IgG1 and IgM formats.
Implementation of lateral flow devices (LFDs) for rabies antigen detection is expected to improve surveillance through the efficient detection of rabid animals in resource-limited settings; however, the use of LFDs for diagnosis remains controversial because some commercially available kits show low sensitivity. Therefore, we compared the diagnostic efficacy of three LFDs (ADTEC, Bionote, and Elabscience kits) paralleled with the direct fluorescent antibody test (dFAT) using fresh samples and investigated the diagnostic accuracies. To do so, we evaluated rabies-suspected samples submitted to the Regional Animal Disease Diagnostic Laboratory III, Philippines. Furthermore, we conducted real-time RT-PCR and sequencing to measure the accuracy of field laboratory diagnosis.
The total number of animals submitted during this study period was 184 cases, including negative control samples. Of these, 53.9% (84 cases) were positive in the dFAT. Dogs were the most common rabies-suspected animal (n = 135). The sensitivities of the ADTEC and Bionote kits were 0.88 (74 cases) and 0.95 (80 cases), respectively. The specificity of both kits was 1.00 (100 cases).
Furthermore, the sensitivity and specificity of the ADTEC kit after directly homogenizing the samples in assay buffer without dilution in phosphate-buffered saline (ADTEC kit DM) were 0.94 (79 cases) and 1.00 (100 cases), respectively. By contrast, there were no positive results using the Elabscience kit among all dFAT-positive samples. The sensitivity and specificity of LFDs make these tests highly feasible if properly used. Therefore, LFD tests can be used to strengthen the surveillance of rabies-infected animals in endemic and resource-limited settings.
The tumor suppressor protein p53 is the protein associated with the viral cancer gene detected and classified in the field of cancer biology by Lane and Crawford in a study of converted cells and tumors in 1979 . The p53 gene family and its proteins are essential in preventing the malignant transformation of normal cells into cancer cells. It is known as the guardian of the genome, located on chromosome 17 in humans. Its coding gene is Tp53, and p53 is a transcription factor that is responsible for controlling cell division, DNA repair, and cancer suppression genes, ultimately playing a vital role in preventing gene mutations. During transformation of human cells, p53 is initially activated by a series of cell signals, including undernourishment, hypoxia, and activation of cancer-causing genes, thus preventing DNA damage during the G1/S phase of the cell cycle G1/S . Failure to repair DNA damage can trigger apoptosis, which prevents cells with abnormal genetic information from continuing to divide and growing into tumors . Once the p53 gene is mutated, these inhibitory functions are impaired.
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Therefore, p53 can be considered as a switch for the mechanism of cancer suppression. Clinically, the p53 protein in the normal human body has been shown in most studies to have a half-life of only about 5 to 20 min. In presence of mutations, protein degradation, or combinations with viral cancer genes, the half-life of the p53 protein is increased; in turn, this event induces the immune system to produce p53 autoantibodies . As a result, there is a clear correlation between the concentration of p53 antibodies in the body and tumor size, cell differentiation level, and lymph node metastasis . The p53 antibodies can be used as a prognostic and tracking indicator for lung, breast, head, and neck cancers. They also show a high diagnostic performance for various solid malignancies—inc
luding rectal cancer , prostate adenocarcinoma , cervical cancer, and oral cancer .