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The Challenge of Parasite Control
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Several newer vaccine types have been developed, some of which are acellular vaccines in that they do not include whole organisms. An example is the subunit vaccine, in which the vaccine consists of particular immunostimulatory antigens only. The hepatitis B vaccine, for instance, is composed only of viral surface proteins. Our understanding of the stimulatory role of T cells in a humoral response has resulted in the development of conjugate vaccines (Figure 9.28). These vaccines rely on a combination of antigens that stimulate both B and T cells. The Haemophilus influenzae vaccine, for instance, combines polysaccharides found in the bacterial capsule with peptides recognized by antigen-specific T cells. The result is a much stronger antibody response then could be elicited with the polysaccharides alone. And most recently, used clinically only since late 2020, are the mRNA vaccines used against the SARS-CoV-2 virus that causes Covid-19. These vaccines consist of viral mRNA that encodes an antigenic viral peptide. The RNA is surrounded by a lipid-based vesicle, which fuses with host cells, allowing the RNA to enter these cells. The viral mRNA is subsequently translated by host translation machinery and the resulting viral peptide is released from the cell where it stimulates an immune response. See the web callout associated with this section to learn about other vaccine types, including those based on nucleic acid.
Vaccines Against COVID-19
Published in Hanadi Talal Ahmedah, Muhammad Riaz, Sagheer Ahmed, Marius Alexandru Moga, The Covid-19 Pandemic, 2023
Majid Khan, Muhammad Faheem, Najmur Rahman, Rizwan Ahmad, M. Zia-Ul-Haq, Muhammad Ria
Generally, these S-domain-based vaccines necessitate a conjunction or adjuvant with an immune-activator to increase the immunogenicity. Numerous studies in mice purports that fusion in vaccinated mice showed a potent systemic neutralizing antibody along with a cellular immune response. Interestingly, smallpox was the first eradicative vaccine produced via subunit concept [12, 16, 17]. Moreover, the pipelined projects for successful immunization plan against COVID-19 are mostly based on subunit protein vaccine [18]. The comparative advantages subunit vaccine is the safety, lesser adversities, potentiating immune system with enhanced T-cell immune response, high titer of neutralizing antibodies with lack of prone of immune system to auxiliary viruses. The Clover Biopharmaceuticals and the University of Queensland have utilized GSK’s adjuvant protocol and on the clinical studies for subunit vaccines are in in-continuation [18, 19].
Plant-Based Adjunct Therapy for Tuberculosis
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
Lydia Gibango, Anna-Mari Reid, Jonathan L. Seaman, Namrita Lall
The only vaccine currently on the market for the treatment of tuberculosis is the live attenuated BCG vaccine derived from Mycobacterium bovis (Khademi et al., 2019). This vaccine has been in use for over 100 years up until today. The vaccine, however, does not have the ability to prevent active pulmonary tuberculosis, latent TB or adult infections (Kaufmann et al., 2010). The BCG vaccine has shown fluctuating efficacy levels in adults, in part said to be due to the different BCG strains used in vaccine design in different countries, as well as exposure to non-tuberculous mycobacteria that mask the efficacy (Davenne and McShane, 2016). Various vaccines are in the preclinical and clinical stages of development, and include genetically modified live attenuated vaccines, which are virally vectored and are considered as a subunit vaccine (Gengenbacher and Kaufmann, 2012; Kaufmann et al., 2010). Subunit vaccines are effectively co-administered with an adjuvant to strengthen this sought-after desired immune response. It is found that combinations of adjuvants with different modes of action are more effective in eliciting both a humoral and cellular response to subunit vaccine antigens by the infected individual (Garçon et al., 2007).
Preclinical developments in the delivery of protein antigens for vaccination
Published in Expert Opinion on Drug Delivery, 2023
Dylan A. Hendy, Alex Haven, Eric M. Bachelder, Kristy M. Ainslie
Vaccination aims to mirror this process while not infecting a person with a potentially dangerous pathogen (Figure 1). With attenuated pathogen vaccines, this problem presents a delicate balance between delivering a vaccine that could cause disease with one potent enough to drive a protective immune response. Utilizing purified antigens from a pathogen (e.g. proteins and sugars) for vaccination (a subunit vaccine) is one method to ensure infection will not occur while simultaneously ensuring a response against a protective antigen is generated. While the use of subunit antigens is safer than attenuated pathogen vaccines, they often need to be delivered with immune stimulating molecules to activate the immune system as would happen in a natural infection and provide a balanced Th1/Th2 response [5]. Furthermore, these vaccines can be improved by delivery strategies that can protect the antigen from degradation, provide targeting to immune cells, reduce adjuvant toxicity, and present antigen to immune cells in a way that mimics natural infection.
Exploring Klebsiella pneumoniae capsule polysaccharide proteins to design multiepitope subunit vaccine to fight against pneumonia
Published in Expert Review of Vaccines, 2022
Jyotirmayee Dey, Soumya Ranjan Mahapatra, S Lata, Shubhransu Patro, Namrata Misra, Mrutyunjay Suar
Klebsiella pneumoniae has emerged as an urgent public health threat in many industrialized countries worldwide. Infections caused by K. pneumoniae are difficult to treat because these organisms are typically resistant to multiple drugs, and the patients have significant co-morbidities. Given the dearth of new antibiotics and the recent incidence of multidrug-resistant strains, there is a critical need for the development of a vaccine against K. pneumoniae infections [20]. The capsule polysaccharide (CPS) of K. pneumoniae has long been viewed as an important virulence factor that promotes resistance to phagocytosis and serum bactericidal activity. Experimental studies have demonstrated that anti-CPS IgG isolated from human volunteers protects mice against K. pneumoniae sepsis [65]. In present times, the multi-epitope subunit vaccine is preferable than the traditional vaccine for several advantages including safety, higher stability, less allergic, autoimmune responses, and a more convenient production process. High throughput next-generation sequencing and advanced genomics and proteomics technologies have brought about a significant change in the computational immunology approach. With the abundance of genomic data and a plethora of immunoinformatics tools available, a better understanding of the immune response of the human body against a multitude of infectious pathogens can be deciphered [66].
Microneedles enable the development of skin-targeted vaccines against coronaviruses and influenza viruses
Published in Pharmaceutical Development and Technology, 2022
Thuy Trang Nguyen, Thi Thuy Dung Nguyen, Nguyen-Minh-An Tran, Huy Truong Nguyen, Giau Van Vo
Subunit vaccines contain just the parts, or antigens, often fused to make them more stable and immunogenic, and formulated together with an adjuvant a substance that will boost the immune response to the proteins (Foged 2011). Subunit vaccines generally cause less adverse reactions than live or inactivated whole-organism vaccines, but they may be less immunogenic because they contain fewer antigens and the purification process often eliminates components that trigger innate immunity (Rappuoli et al. 2014). For instance, the subunit vaccine for SARS-CoV2 that contains spike (S), envelope (E), membrane (M), and nucleocapsid (N) from viral antigens. A residues 319–545 of the SARS-CoV-2 was used in a recent vaccine (Yang et al. 2020), providing a rationale for the development of a protective vaccine through the induction of antibodies against the receptor-binding domain.