China 
Africa 
Explore chapters and articles related to this topic
Controlled Vaccine Delivery
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
The most common form of single-injection vaccines is biodegradable particles that exhibit degradation-mediated antigen release over the course of weeks or months. By delivering antigen over time, these vaccines seek to promote the formation of antigen-specific memory B cells, affinity maturation, long-lived plasma cells, and ultimately protective levels of neutralizing antibodies. More recently, the potential role of cellular immunity has also become better understood and appreciated, though current vaccines are largely considered to work by establishing humoral immunity. Lymph node-targeting nanoparticles have also been explored as an alternative delivery strategy to enhance the magnitude of the immune response via antigen persistence in an immune cell-rich environment, albeit delivering antigen over shorter time periods.14,15 In order for single-injection vaccines to be clinically and ethically viable, they must confer immunity that is noninferior to current multidose regimens. Although there has been substantial preclinical work using controlled-release vaccines, this technology has yet to be commercialized due to challenges associated with biologics. The two key challenges facing single-injection vaccines today are release kinetics and antigen stability. These challenges are a consequence of multiple factors, including the type of vaccine, formulation method, encapsulating material, adjuvant load, and stabilizing excipients, which together determine the success of a controlled-release vaccine.
Hybrid System by AINFS and AINFNNS for Robust Control of Nonlinear System
Published in Dong Hwa Kim, Tuning Innovation with Biotechnology, 2017
The immune system has two types of response: primary and secondary. The primary response is the reaction when of the immune system when it first encounters the antigen. At this point, the immune system learns about the antigen, thus preparing the body for any further invasion from that antigen. This learning mechanism creates the immune system’s memory. The secondary response occurs when the same antigen is encountered again. This response is characterized by a more rapid and more abundant production of antibody resulting from the priming of the B-cells (B-lymphocytes) as in the primary response. When a naive B-cell encounters an antigen molecule through its receptor, the cell gets activated and begins to divide rapidly; the progenity derived from these B-cells differentiate into memory B-cells and effector B-cells or plasma cells. The memory B-cells has a long life span and they continue to express membrane bound antibody with the same specificity as the origin parent B-cell [221, 222, 225].
Wrong Resemblance? Role of the Immune System in the Biocompatibility of Nanostructured Materials
Published in Dan Peer, Handbook of Harnessing Biomaterials in Nanomedicine, 2021
Following the initial recognition of an antigen a B cell produces mainly IgM antibody. Further B cell stimulation in the lymph node may change the isotype of the secreted antibody (“class switching”) to either IgA, IgG, or IgE, all with the same antigen specificity as the initially produced IgM. There is conflicting data concerning the role of T cells in this process, probably due to that the cytokines required for class switching may be produced by other cells than T cells [5, 6]. This is important since it implies that class-switching also occurs for antibodies directed to T-cell independent antigens, i.e., antibodies produced without the involvement of T cells. Equally important is that the B cells expressing a receptor with high affinity for antigen are expanded and that the maturation also involves the formation of so-called memory B cells. Thus, the recognition of antigen selects B cell clones that express a receptor appropriate for such recognition and hence is able to produce secreted antibody also recognizing that antigen. Memory B cells enable a quick formation of antibodies to microbial antigens when these are encountered a second time, which effectively serves to limit the spread of an infectious agent in the body. The observation that cells of the immune system support recall response is a hallmark of adaptive immunity. As a consequence, the function of the immune system is dependent on past exposures to antigens, which obviously introduces a significant variability in the immune responses among any group of individuals. Although antibodies are selected on the basis of their ability to form complexes with an antigen, this does not imply that such antibodies may only bind to this antigen. Cross reactivity often permits antibodies to bind substances structurally similar to their cognate antigen [7–10]. While to some extent it is possible to predict the antigenicity of proteins with a known structure [11], the considerable variation between healthy individuals in the reactivity of antibodies [12] makes it essentially impossible to predict if antibodies to antigens, e.g., in formulations involving nanomaterials, may have been preformed. Fortunately, several tests are now possible to broadly investigate if antibody reactivity would allow for the binding of Ig to chosen materials [12].
Polymer-based nano-therapies to combat COVID-19 related respiratory injury: progress, prospects, and challenges
Published in Journal of Biomaterials Science, Polymer Edition, 2021
From the history of vaccine development, it is well established that vaccination is one of the most effective strategies to prevent and control the spread of infectious diseases, where naturally developed immunity induces protective long-term immune memory in patients.[132] In general, vaccines introduce specific viral antigens on the cell surface of antigen-presenting cells (APCs), particularly dendritic cells, embodied in the major histocompatibility complex (MHC) I and II.[133] Such an event triggers the adaptive immune system by recognizing these antigens as invaders and induces antibodies production or T cells to eliminate these unwanted invaders. Consequently, memory B cells in the body develop virus-specific antibodies on its cell surface, which triggers a fast immune response to clear the similar viral infection in the future. There are three different generations of vaccine formulations currently used to trigger immune responses against infection, including live attenuated (whole inactivated pathogen) vaccines or first-generation vaccines, recombinant subunit vaccines (second-generation), and RNA/DNA vaccines or third-generation vaccines.[134,135] Since the outbreak of COVID-19, several different vaccine candidates have been developed and reached clinical phases due to a high urgency to halt the pandemic.[136]
A complete immunoglobulin-based artificial immune system algorithm for two-stage assembly flowshop scheduling problem with part splitting and distinct due windows
Published in International Journal of Production Research, 2019
The adaptive immunity consists of two stages: primary and secondary responses. For the primary response, B-cell receptors and T-cell receptors are produced by different combinations of V and J gene segments, named gene rearrangement, in the primary lymphoid organ. Then the B cells will leave the bone marrow and go into the peripheral lymphoid tissue while the T cells will leave the thymus and go into the second lymphoid tissue. By B-cell receptors, B cells capture the pathogen and take it into the nearest peripheral lymphoid tissue. As the circulating B cells pass through the T-cell zones, they make transient interactions that the T cells use its receptors to screen the pathogens presented by the B cells. When the B cells present pathogens recognised by T cells, called cognate interactions, these B cells are subject to somatic hypermutation and isotype switching, and they will eventually produce plasma cells that make high-affinity antibodies of three isotypes, IgG, IgA and IgE, with the help of T cells. However, if the cognate interactions do not happen, only IgM is produced. During a primary response, the pathogen-specific B cells and T cells give rise both to short-lived effector cells that work to stop the infection and to long-lived memory B cells and memory T cells. These memory cells will be easily activated by pathogen to proliferate and differentiate into effector cells. More effective antibodies will be produced to bind and destroy the same pathogen. This stronger and quicker immune response is called secondary response. The details of primary response and secondary response are presented based on the book by Parham (2014).