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Pathogenicity and Virulence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The staphylococci, more commonly the virulent strains, produce several cyto-toxins that act on a variety of cells. The staphylococcal hemolysins kill both erythrocytes and leukocytes, while the leukocidin is cytotoxic only for leukocytes. Though there is evidence that the hemolysin can function to impair both chemotaxis and subsequent lysosomal fusion, the actual significance of these toxins in production of disease is not yet clearly defined. However, the production of a leukocidin by strains of E. coli correlates well with their virulence.
Choerospondias axillaris (Hog plum)
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Wild Plants, 2020
The study of the mononuclear phagocyte system, thymus, and serum hemolysin gives information about the immunity system. The mononuclear phagocyte system has phagocytosis and bactericidal action and antitumor effects. The thymus is the central immune organ for the differentiation and maturation of T lymphocytes. Serum hemolysin is a sensitive marker to reflect and test the humoral immune function. TFC may influence cellular immunity and humoralimmunity by enhancing the phagocytic function of mononuclear macrophage. TFC may enhance cellular immunity and increase the thymus weight. TFC increased the content of serum hemolysin in normal mice and the antibody titer induced by contact again antigen, indicating that TFC could enhance humoral immunity, relating to IgM and IgG. Thus, TFC could improve the celiac macrophage activity and specific immunity of mice (Liu et al. 2013). C. axillaries could enhance cellular, humoral immune function, and sports endurance of mice (Deng and Ji 2002).
Radiation Immunology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
Primary response is generally more radiosensitive than the secondary response. Ionizing radiation reduces the formation of antibody. The extent of decrease is associated with the dose, time of antigenic stimulus, and nature of the antigen. It has been reported3 that depression of the primary hemolysis response occurred in rats when 300 R was given at various times during the week, before and 5 days after a single injection of sheep erythrocytes. An X-ray exposure of 175 R given 3 days before the antigen caused a greater depression of the hemolysin response than 600 R given 2 days after the antigenic stimulus.3,4 The relationship between the effect of irradiation on hemolysin formation and the time of antigen is summarized below:5The maximum reduction of antibody formation occurs when irradiation was given 12–24 hr before the administration of the antigen.When the antigen is administered just after irradiation, the amount of antibodies produced is almost equal to normal values, but the production rate is less.On administering the antigen shortly before irradiation, the results are similar, but the antibody production rate is higher than normal.
Immunomodulatory activity of puerarin in RAW264.7 macrophages and cyclophosphamide-induced immunosuppression mice
Published in Immunopharmacology and Immunotoxicology, 2021
Yuexing Chang, Ailing Guo, Yanlin Jing, Junjie Lin, Yuanyuan Sun, Lulu Kong, Haohang Zheng, Yun Deng
The serum hemolysin level was assessed, as described previously [5]. On the first day of continuous administration for 10 days, 5% of the chicken erythrocytes were intraperitoneally injected with 0.2 ml for 3 days. The same intragastric administration remained as before for 3 days. Simultaneously, 5% of the chicken erythrocytes were intraperitoneally injected with 0.2 ml. On the first day of the last injection of the 5% of chicken erythrocytes, blood samples were collected from the orbital venous plexus and centrifuged at 5000 r/min and 4 °C for 5 min. The serum was 100 times diluted with normal saline. Then 0.5 ml of the diluted serum, 0.5 ml of 5% chicken erythrocytes, and 0.5 ml 10% guinea pig serum were mixed at 37 °C for 30 min. The reaction was terminated with an ice water bath. Similarly, the suspension of the blank serum was obtained by adding 0.25 ml of 5% chicken erythrocytes and 0.5 ml 10% guinea pig serum to 1.25 ml of normal saline. After centrifugation of the suspension, the absorbance of the supernatants was measured at 540 nm. The serum half hemolysis value (HC50) was calculated according to the following formula: 1 is the absorbance value of the diluted mouse serum, A2 is the absorbance of the blank serum, and B is the dilution factor of the mouse serum.
Inhibitory effect of norharmane on Serratia marcescens NJ01 quorum sensing-mediated virulence factors and biofilm formation
Published in Biofouling, 2021
Huai-Zhi Luo, Jin-Wei Zhou, Bing Sun, Huan Jiang, Shi Tang, Ai-Qun Jia
To identify the anti-QS activity of ILEE on S. marcescens NJ01, the virulence factors and biofilm formation by S. marcescens were assayed. Intracellular prodigiosin pigment production is directly regulated by the QS-signaling mechanism of S. marcescens strains from environmental or clinical origins (Slater et al. 2003). Generally, the pigments produced by pathogenic microbes such as Staphylococcus aureus and Pseudomonas aeruginosa are necessary virulence factors for their invasion, survival and lethality, but the prodigiosin produced by S. marcescens is not an essential virulence factor (Liu and Nizet 2009; Zhou et al. 2016). In this study, the prodigiosin was significantly reduced from 87.6% to 94.3% at 0.5 and 2.0 mg ml−1 of ILEE, respectively (Figure 3a). Hemolysin, which is produced by various pathogenic bacteria and has been proposed to be responsible for their pathogenesis (Shimuta et al. 2009), was also significantly reduced from 63.9% to 78.3% (Figure 3d). In addition, the productions of protease, lipase, EPS and biofilm were inhibited by ∼ 38.9%, 37.1%, 39.8% and 54.7% after being exposed to 2.0 mg ml−1 ILEE (Figure 3b, c, e, f).
Mycotic infections – mucormycosis and oral candidiasis associated with Covid-19: a significant and challenging association
Published in Journal of Oral Microbiology, 2021
Manjusha Nambiar, Sudhir Rama Varma, Mohamed Jaber, S. V. Sreelatha, Biju Thomas, Arathi S. Nair
Candida releases certain extracellular enzymes that have a locally destructive effect on host tissues.7 The Secreted Aspartyl Proteinases (SAPs) produced by C. albicans can directly cause host cell damage, induce growth of hyphae for tissue invasion, increase adherence following receptor site exposure, and it also causes destruction of host immunoglobulins and other defense proteins [6,10]. Hemolysins produced by Candida are substances that break down red blood cells, and are an important attribute that helps in its survival within the host through its increased ability for iron sequestration. Hemolysin production by candida increases with increased glucose concentration, and this could be a predisposing factor for candidiasis in uncontrolled diabetics [8]. Under normal health conditions, the multiplication, and growth of candida are prevented by other organisms present in the oral microbiota, and therefore, at lower levels, it cannot bring about pathological alterations in the oral mucosa [11]. Reduced production of antimicrobial proteins such as lysozyme and lactoferrin in patients with hyposalivation can also result in decreased antifungal properties, leading to the development of oral candidiasis. The downregulation of the immune system in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, therefore, could be a causal pathway for the increased oral manifestations associated with COVID-19, mainly the ones of fungal origin [11].