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The Invisible Army
Published in Norman Begg, The Remarkable Story of Vaccines, 2023
The part of the pathogen that the immune system recognises is known as the antigen. The antigens in vaccines are derived from either bacteria or viruses (apart from the malaria vaccine, which contains antigen derived from a single-celled parasite, called plasmodium). Come and meet these amazing invisible creatures.
Nanomaterials in COVID-19 Drug Development
Published in Debmalya Barh, Kenneth Lundstrom, COVID-19, 2022
Alaa A. A. Aljabali, Ángel Serrano-Aroca, Kenneth Lundstrom, Murtaza M. Tambuwala
Antigens from microbe/virus, toxins, or surface proteins are generally used as vaccine components. Antigens trigger the body’s immune system to produce antibodies, which in case of microbial, toxin, or cancer cell invasion recognize the invasion and kill the relevant target. Antigen proteins, generally combined with adjuvants, are administered directly to induce immune responses. Nanomaterials can also function as antigen carriers and, in some cases as adjuvants Nanomaterial-based vaccines can protect anti-antigens from premature degradation, and guarantee controlled delivery, improved antigen stability and controlled immunogen distribution, and increase the time of antigenic exposure to antigen-presenting cells (APCs) [44].
Respiratory Diseases
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Aref T. Senno, Ryan K. Brannon
Antigen tests have additionally been developed with the goal of providing rapid, point-of-care testing. Antigen-based testing has had mixed results, with poor average sensitivity of 56% (range 0–94%) but with excellent sensitivity (99.5%) [146]. However, antigen-based testing may improve over time and provide a low-cost, rapid alternative to NAAT.
Pitfalls of SARS-CoV-2 antigen testing at emergency department
Published in Infectious Diseases, 2022
Eleonora Cottone, Frederik Van Hoecke, Geert Antoine Martens, Emmanuel De Laere, Roos De Smedt, Steven Vervaeke, Merijn Vanhee, Dieter De Smet
In general, SARS-CoV-2 rapid antigen tests demonstrate high specificity, but variable sensitivity [7]. Many questions have been raised about their diagnostic performance in a hospital setting. In its statement on antigen detection for diagnosis of SARS-CoV-2, WHO does not specify how these tests should be used in hospitals [6]. Besides diagnostic use for COVID-19, antigen tests are also used in asymptomatic patients to detect contagious individuals, both in medical and non-medical settings. A patient is considered contagious if the SARS-CoV-2 viral load equals or exceeds 5 log10 (=105) copies/mL [9–14]. In this study, the diagnostic performance of the Roche SARS-CoV-2 rapid antigen test was evaluated as compared with RT-PCR results for 464 COVID-19 suspected patients admitted to the hospital ER department.
Point-of-care COVID-19 testing in the emergency department: current status and future prospects
Published in Expert Review of Molecular Diagnostics, 2021
Larissa May, Nam Tran, Nathan A. Ledeboer
Immunoassays are used to detect SARS-CoV-2 viral antigens such as the spike and nucleocapsid proteins. Antigen testing offers a compromise between clinical performance (e.g. sensitivity and specificity) versus speed and accessibility. Unlike molecular approaches, immunoassay reagent production is less constrained and testing platforms can range from point-of-care formats to full-sized automated analyzers that are commonly available in hospital laboratories. Antigen testing may be limited to testing in symptomatic individuals only, but more recently, some tests have received FDA authorization for testing in asymptomatic populations. Negative antigen results in symptomatic patients may require follow-up testing via molecular approaches. Results may be qualitatively or quantitatively reported.
Targeting the spectrum of immune checkpoints in prostate cancer
Published in Expert Review of Clinical Pharmacology, 2021
Laura A. Sena, Samuel R. Denmeade, Emmanuel S. Antonarakis
Antigens are molecules that are recognized and elicit an immune response in the context of inflammation. Cancer antigens are often derived from mutated self-peptides against which the immune system has not been tolerized and are called “neoantigens.” Production and presentation of neoantigens are likely required for a tumor adaptive immune response. Neoantigen burden loosely correlates with tumor mutational burden (TMB), which is an important biomarker of response to ICB [58]. High TMB can be driven by loss of function of one or more of the DNA mismatch repair proteins (MSH2, MSH6, MLH1, and PMS2), i.e. mismatch repair deficiency (dMMR)[59], or by POLE or POLD1 polymerase gene mutations affecting the proofreading/exonuclease domains. Advanced dMMR solid tumors exhibit high response rates to ICI [60] and case reports indicate that solid tumors with POLE or POLD1 mutations (which are much more rare) may behave similarly [61–63]. Both high TMB (>10 mutations per megabase (mut/Mb)) and dMMR are FDA-approved indications for use of ICB in patients with advanced solid tumors, irrespective of histologic type.