Oral Vaccines: A Better Future of Immunization

Kwong, Keith Wai-Yeung; Xin, Ying; Lai, Nelson Cheuk-Yin; Sung, Johnny Chun-Chau; Wu, Kam-Chau; Hamied, Yusuf Khwaja; Sze, Eric Tung-Po; Lam, Dominic Man‐Kit

doi:10.3390/vaccines11071232

Cited by 10 publications

(4 citation statements)

References 139 publications

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“…A novel delivery system that can carry cargo antigens and adjuvant to the GALT to induce local protective responses would be a game changer for the development of new oral vaccines. Aside from their mucosal immunological benefits over injected vaccines, their practicality (being needle-free) from a cost, administration and safety perspective makes oral vaccines extremely desirable for mass immunisation and pandemic preparedness [ 3 ].…”

Section: Discussionmentioning

confidence: 99%

“…There is an urgent need for new and improved vaccines that can directly target the initial infection site, which, for 90% of infections, are mucosal sites [ 2 ]. To this end, immunising via the oral route is attracting interest, as not only does it induce protective responses in the intestinal tract, but also in distal mucosal sites and systemically [ 3 ]. Furthermore, without the need for needles, oral vaccines are safer and cheaper and can be self-administered.…”

Section: Introductionmentioning

confidence: 99%

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Fasting before Intra-Gastric Dosing with Antigen Improves Intestinal Humoral Responses in Syrian Hamsters

Wood,

Hughes,

Trussell

et al. 2024

Vaccines

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Oral vaccines, unlike injected, induce intestinal secretory immunoglobulin A (sIgA) mimicking our natural defense against gut pathogens. We previously observed sIgA responses after administering the Clostridioides difficile colonisation factor CD0873 orally in enteric capsules to hamsters. Enteric-coated capsules are designed to resist dissolution in the stomach and disintegrate only at the higher pH of the small intestine. However, the variable responses between animals led us to speculate suboptimal transit of antigens to the small intestine. The rate of gastric emptying is a controlling factor in the passage of oral drugs for subsequent availability in the small intestine for absorption. Whilst in humans, food delays gastric emptying, in rats, capsules can empty quicker from fed stomachs than from fasted. To test in hamsters if fasting improves the delivery of antigens to the small intestine, as inferred from the immune responses generated, 24 animals were dosed intragastrically with enteric capsules containing recombinant CD0873. Twelve hamsters were fasted for 12 h prior to each dose and the other 12 fed. Significantly higher sIgA titres, with significantly greater bacterial-adherence-blocking activity, were detected in small intestinal lavages in the fasted group. We conclude that fasting in hamsters improves intestinal delivery leading to more robust responses.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fasting before Intra-Gastric Dosing with Antigen Improves Intestinal Humoral Responses in Syrian Hamsters

Wood,

Hughes,

Trussell

et al. 2024

Vaccines

View full text Add to dashboard Cite

show abstract

“…Oral vaccines present challenges in clinical trials. Unlike injectable vaccines, which are typically administered in one or multiple doses depending on the vaccine type, individual age, weight and immune system, oral vaccines require additional testing to study their tolerance to the acidic environment of the stomach and their ability to remain intact and activate an immune response during the digestive process ( 124 ).…”

Section: Feasibility and Challenges Of Oral Vaccinesmentioning

confidence: 99%

Recent development of oral vaccines (Review)

Liu,

Lam,

Luan

et al. 2024

Exp Ther Med

Self Cite

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Oral immunization can elicit an effective immune response and immune tolerance to specific antigens. When compared with the traditional injection route, delivering antigens via the gastrointestinal mucosa offers superior immune effects and compliance, as well as simplicity and convenience, making it a more optimal route for immunization. At present, various oral vaccine delivery systems exist. Certain modified bacteria, such as Salmonella , Escherichia coli and particularly Lactobacillus , are considered promising carriers for oral vaccines. These carriers can significantly enhance immunization efficiency by actively replicating in the intestinal tract following oral administration. The present review provided a discussion of the main mechanisms of oral immunity and the research progress made in the field of oral vaccines. Additionally, it introduced the advantages and disadvantages of the currently more commonly administered injectable COVID-19 vaccines, alongside the latest advancements in this area. Furthermore, recent developments in oral vaccines are summarized, and their potential benefits and side effects are discussed.

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“…In orally induced immune responses, the production of secretory immunoglobulin A (IgA) in GALT is amplified, acting as a barrier to mucosal surface pathogens, whereas injected vaccines predominantly yield immunoglobulin G (IgG) for systemic protection [100]. Secretory IgA, prevalent in mucous secretions, is crucial for robust mucosal immunity, serving as the primary defense at mucosal sites to ward off pathogen infections [101].…”

Section: The Immune System: An Overview Of the Response To Vaccinationmentioning

confidence: 99%

Vaccine Responses in Patients with Liver Cirrhosis: From the Immune System to the Gut Microbiota

Airola,

Andaloro,

Gasbarrini

et al. 2024

Vaccines

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Vaccines prevent a significant number of deaths annually. However, certain populations do not respond adequately to vaccination due to impaired immune systems. Cirrhosis, a condition marked by a profound disruption of immunity, impairs the normal immunization process. Critical vaccines for cirrhotic patients, such as the hepatitis A virus (HAV), hepatitis B virus (HBV), influenza, pneumococcal, and coronavirus disease 19 (COVID-19), often elicit suboptimal responses in these individuals. The humoral response, essential for immunization, is less effective in cirrhosis due to a decline in B memory cells and an increase in plasma blasts, which interfere with the creation of a long-lasting response to antigen vaccination. Additionally, some T cell subtypes exhibit reduced activation in cirrhosis. Nonetheless, the persistence of memory T cell activity, while not preventing infections, may help to attenuate the severity of diseases in these patients. Alongside that, the impairment of innate immunity, particularly in dendritic cells (DCs), prevents the normal priming of adaptive immunity, interrupting the immunization process at its onset. Furthermore, cirrhosis disrupts the gut–liver axis balance, causing dysbiosis, reduced production of short-chain fatty acids (SCFAs), increased intestinal permeability, and bacterial translocation. Undermining the physiological activity of the immune system, these alterations could impact the vaccine response. Enhancing the understanding of the molecular and cellular factors contributing to impaired vaccination responses in cirrhotic patients is crucial for improving vaccine efficacy in this population and developing better prevention strategies.

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Oral Vaccines: A Better Future of Immunization

Cited by 10 publications

References 139 publications

Fasting before Intra-Gastric Dosing with Antigen Improves Intestinal Humoral Responses in Syrian Hamsters

Fasting before Intra-Gastric Dosing with Antigen Improves Intestinal Humoral Responses in Syrian Hamsters

Recent development of oral vaccines (Review)

Vaccine Responses in Patients with Liver Cirrhosis: From the Immune System to the Gut Microbiota

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