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Specific Host Restance: The Effector Mechanisms
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Antibody alone does not bring about the osmotic lysis of bacteria. When antibody binds to the surfaces of parasites, however, the immune complexes that are formed will bind and activate complement. It is the products released by the activated complement that lyse the bacteria. Gram-negative bacilli are particularly susceptible to complement-mediated lysis. Antibodies of the IgA, IgM, and IgG classes activate complement. In addition to blocking microbial attachment to mucosal surfaces, secretory IgA also functions by activating complement. Bacteriolysis probably occurs rarely in vivo since complement components generated early in the reaction provide such potent opsonins that microbes are likely to undergo phagocytosis before they can be lysed.
Role of Bacteria in Urinary Tract Infections
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
JebaMercy Gnanasekaran, Kannan Balaji, K. Balamurugan
Lipoteichoic acid (LTA) is a surface-associated adhesion amphiphile from gram-positive bacteria made up of a polymer of repetitive 1,3-phosphodiester-linked glycerol-I-phosphate units with a glycolipid anchor (Leopold & Fischer, 1992). It gets released from the gram-positive bacterial cells during bacteriolysis induced by host factors like lysozyme, cationic peptides from leucocytes, or during the antibiotic treatment. It binds to target cell receptors like CD14 or toll-like receptors. LTA can interact with antibodies and activate the passive immune kill phenomenon. LTA is similar to the endotoxin lipopolysaccharide and shares several of its pathogenetic properties (Dishon et al., 1967). Chemotaxis of human neutrophils and phagocytosis were also inhibited by LTA (Raynor et al., 1981; Card et al., 1994). LTA also induced expression of macrophage inflammatory protein 1 alpha. These findings suggest that LTA may have a role in the regulation, recruitment, and activation of leukocytes in inflammatory sites (Nonogaki et al., 1995). LTA, teichoic acid, and peptidoglycan each inhibit proliferation of fibroblasts by a still undefined mechanism and also act on T cells to activate nuclear factor kappa B. LTA, therefore, seems to be a versatile immunomodulator that can alter cell responses in inflammatory conditions (Elgavish et al., 2000).
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Published in Anton Sebastian, A Dictionary of the History of Medicine, 2018
Antibody [Greek: anti, against + bodig, body] An immunoglobulin that binds to a specific antigen. Their presence in blood of atopic or allergic individuals was demonstrated by a British immunologist of German origin, Otto Carl Willy Prausnitz (1876–1973) and Heinz Kustner in 1921. They were shown to be gamma globulins by Arne Wilhelm Kaurin Tiselius (1902–1971) and Elvin Abraham Kabat in 1939. Prausnitz transferred fish hypersensitivity of his partner Kustner to his own skin by a method of sensitization and the hypersensitive reaction of the skin was named the Prausnitz–Kustner reaction. His finding was subsequently used clinically to diagnose atopic hypersensitivity Antibodies in the IgA globulin fraction of atopic individuals were discovered by J.F. Heremans and co-workers in Belgium. IgE antibodies were identified in serum by Kimishige Ishizaka and co-workers in Denver in 1970.The presence of a higher concentration of IgE antibodies in the serum of patients with hay fever and asthma was also demonstrated by Ishizaka and this contributed to further research in the pathogenesis of immediate hypersensitivity reactions. See immunoglobulins, bacteriolysis.
Factors determining phage stability/activity: challenges in practical phage application
Published in Expert Review of Anti-infective Therapy, 2019
Ewa Jończyk-Matysiak, Norbert Łodej, Dominika Kula, Barbara Owczarek, Filip Orwat, Ryszard Międzybrodzki, Joanna Neuberg, Natalia Bagińska, Beata Weber-Dąbrowska, Andrzej Górski
Endolysins (also known as phage lysozymes, lysins, or muralytic/mureolytic enzymes) are bacteriophage-encoded peptidoglycan hydrolases, synthesized in phage-infected bacterial cells at the end of the multiplication cycle [209]. These enzymes target the integrity of the cell wall and are designed to attack one of the four major bonds in the peptidoglycan [210]. As a result they weaken the mechanical strength and resistance of the bacterial cell wall, which is needed to withstand the internal cytoplasmic turgor (osmotic) pressure, causing bacteriolysis and the subsequent release of the bacteriophage progeny [211]. Phage endolysins constitute an enormously diverse group of proteins with respect to their primary structures and enzymatic properties. Generally, endolysins infecting Gram-positive bacteria contain both an enzymatic active domain (EAD) and a cell binding domain (CBD), while most endolysins from a Gram-negative background possess an EAD and, usually, they lack a specific CBD [212].
Synergistic activity of antibodies in the multicomponent 4CMenB vaccine
Published in Expert Review of Vaccines, 2022
Viola Viviani, Alessia Biolchi, Mariagrazia Pizza
The mechanism of SBA relies on the activation of the complement classical pathway (CP). In particular, the outcome of the SBA assay is influenced by multiple factors: the concentration of the complement and of the bactericidal antibodies in the serum sample, the avidity of the antigen-specific antibody binding, and finally the density and the levels of expression of the targeted antigen on the bacterial surface. Indeed, the CP begins when the density of antigen–antibody complexes is enough to enable the proximity of the Fc regions of immunoglobulins, which in turn recruit the C1q present in the C1 complex. This binding triggers the activation of the entire complement pathway that ultimately leads to bacteriolysis.
Current and emerging drug treatment strategies to tackle invasive community-associated methicillin-resistant Staphylococcus aureus (MRSA) infection: what are the challenges?
Published in Expert Opinion on Pharmacotherapy, 2023
Antonio Vena, Nadia Castaldo, Laura Magnasco, Martina Bavastro, Alessandro Limongelli, Daniele Roberto Giacobbe, Matteo Bassetti
Inadequate prompt management of CA-MRSA has a significant impact on clinical outcomes. Although several anti-MRSA molecules are now available in the antimicrobial pipeline, the optimization of the antimicrobial strategy is crucial, especially in critical settings. Notably, some strains might continue to exert tissue damage through PVL and other virulence effectors for a certain time after the administration of an anti MRSA antibiotic. In these cases, antitoxin antimicrobials should be selected, to contemporary achieve bacteriolysis and removal of the toxins [64,68].