The Space Shuttle
Norman Begg in The Remarkable Story of Vaccines, 2023
An adjuvant is an important ingredient for some vaccines. These performance-enhancing substances are very useful from a manufacturing perspective. With an improved immune response, it is possible to lower the amount of the active component in the vaccine and make more doses. This can be critical when manufacturing needs to be ramped up quickly, for example in a response to a flu pandemic. The science of adjuvants has mushroomed in recent years. Many naturally derived products have been found to enhance the immune response to vaccines. Squalene is an oil found in many plants and animals, especially sharks. The oil that lubricates human skin and hair contains squalene. It is used as an adjuvant for some flu vaccines. Another adjuvant, monophosphoryl liquid (MPL) is isolated from the surface of a type of salmonella bacteria. The ingredients of these modern bespoke adjuvants are not so easy to come by. For example, one adjuvant is derived from a plant extract from a soap bark tree, Quillaja saponaria, which grows only in central Chile, in protected plantations.
Rationale and technique of malaria control
David A Warrell, Herbert M Gilles in Essential Malariology, 2017
However, due to the antigenic diversity of the malaria parasite, the identification and development of vaccine candidate antigens are complex and high-risk undertakings. A multi-stage, multi-component vaccine that targets several antigens from several stages of the life cycle would have the best chance of controlling the growth of the parasite in the host and eventually the community. Asexual blood-stage vaccines, which prevent the merozoite from entering or developing within red blood cells, would directly impact disease morbidity and death. At present, more than 10 promising candidate vaccines for P. falciparum are in various stages of research. The adjuvant (a neutral substance that enhances the body’s immune response to antigens) used with a vaccine is important and several novel adjuvants are also being studied.
Neurological events following immunizations
Avindra Nath, Joseph R. Berger in Clinical Neurovirology, 2020
There are several important determinants of vaccine efficacy, which modulate the intensity of peak antibody responses. The nature of the vaccine antigen and its intrinsic immunogenicity are important, with some antigens being inherently more immunogenic than others. Live vaccines generally elicit stronger innate immune responses and thus stronger antibody responses. Non-live vaccines frequently require the use of adjuvants, or agents which increase the stimulation of the immune system by enhancing antigen presentation; aluminum salts are frequently used as adjuvants [18]. Many vaccines, particularly inactivated vaccines, require multiple doses to induce high and sustained antibody responses, or may require repeated administration at particular intervals. Antibody persistence is critically important; for the vaccine immune response to last, memory B cells, which are capable of recognizing and responding to an antigen challenge and subsequently proliferating and differentiating into antibody producing plasma cells, must be produced. Antibody persistence may be dependent on several different determinants, including the nature of the vaccine (live vs. inactivated), interval between doses, and age at immunization.
Targeting strategies of liposomal subunit vaccine delivery systems to improve vaccine efficacy
Published in Journal of Drug Targeting, 2019
Rui Yu, Yaping Mai, Yue Zhao, Yanhui Hou, Yanhua Liu, Jianhong Yang
Adjuvants are key ingredients of vaccines that potentiate the immune response and/or modulate it toward a desired immune response. Adjuvants usually exhibit multiple mechanisms such as depot formation, increased antigen presentation by antigen presenting cells (APCs) and induced secretion of immune-modulatory cytokines. The first adjuvants used in humans were aluminium-based adjuvants, which rarely impart cytotoxic T lymphocyte (CTL) responses; other common adjuvants such as oil emulsions and saponins usually induce local side effects [4]. Therefore, to obtain the desired immune response and to treat many newly emerging diseases, more powerful, improved adjuvants need to be developed. In recent years, nanoparticles have been found to be potential candidate adjuvants for vaccine formulations. Among the various types of nanoparticles, liposome-based carriers have attracted much attention, owing to their enormous application potential.
Where are we and how far is there to go in the development of an Acinetobacter vaccine?
Published in Expert Review of Vaccines, 2021
Adjuvants enhance the immunogenicity and efficacy of the vaccine and are commonly used in most of the licensed human subunit vaccines. While alum remains the widely used and predominant adjuvant in current human vaccines, alternative novel adjuvants (such as MF-59, AS-01 to AS-04 etc.) have also been approved recently for human use [132]. Although detailed discussion on the vaccine adjuvant and delivery system is out of the scope of this review, it is encouraging to note that MF-59 and several experimental adjuvants (such as chitosan, flagellin etc.) have been evaluated in preclinical development of Acinetobacter vaccines during this period. On the hand, CFA/IFA have been used in several studies (Table 1). They are potent adjuvants but highly toxic, and their use even in the experimental vaccine studies have been discouraged for animal welfare consideration.
Nasal delivery of H5N1 avian influenza vaccine formulated with GenJet™ or in vivo-jetPEI® induces enhanced serological, cellular and protective immune responses
Published in Drug Delivery, 2018
Weiping Cao, Margarita Mishina, Samuel Amoah, Wadzanai P. Mboko, Caitlin Bohannon, James McCoy, Suresh K. Mittal, Shivaprakash Gangappa, Suryaprakash Sambhara
The spread of highly pathogenic AIV in birds and domestic poultry, the emergence of novel virus strains, and the increasing number of their direct transmission to humans have raised significant concern about the avian influenza pandemic threat (Poovorawan et al., 2013). Vaccination to prevent infection is no doubt the most cost-effective public health strategy. Unfortunately, the current avian influenza vaccines are poorly immunogenic even with high dose or alternative immunization route as shown in animal studies and human clinical trials (FDA, 2007; Layton et al., 2011a, 2011b; Cao et al., 2016; Jones et al., 2017). The manufacturing capacity is also limited to produce enough vaccine in a pandemic situation. Adjuvants have been shown to provide great advantages in enhancing the immunogenicity of vaccine, such as dose sparing, increased vaccine efficacy in elder and immunocompromised populations, and a broader protective immunity (Reed et al., 2013). Aluminum salts are the most commonly used adjuvants in human vaccines (Reed et al., 2013). In recent years, influenza vaccines formulated with two squalene-based oil-in-water emulsions have been approved for use in human in the US and Europe for seasonal and pandemic influenza (FDA, 2015). Although both adjuvants hold great promise for enhancing the immunogenicity of vaccine, AS03 has been associated with narcolepsy (Ahmed et al., 2014) and these are proprietary adjuvants. Therefore, challenges remain for developing new adjuvants and alternative delivery systems for avian influenza vaccine.
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