Alternative Methods of Vaccine Delivery: An Overview of Edible and Intradermal Vaccines

Abstract

Vaccines are recognized worldwide as one of the most important tools for combating infectious diseases. Despite the tremendous value conferred by currently available vaccines toward public health, the implementation of additional vaccine platforms is also of key importance. In fact, currently available vaccines possess shortcomings, such as inefficient triggering of a cell-mediated immune response and the lack of protective mucosal immunity. In this regard, recent work has been focused on vaccine delivery systems, as an alternative to injectable vaccines, to increase antigen stability and improve overall immunogenicity. In particular, novel strategies based on edible or intradermal vaccine formulations have been demonstrated to trigger both a systemic and mucosal immune response. These novel vaccination delivery systems offer several advantages over the injectable preparations including self-administration, reduced cost, stability, and elimination of a cold chain. In this review, the latest findings and accomplishments regarding edible and intradermal vaccines are described in the context of the system used for immunogen expression, their molecular features and capacity to induce a protective systemic and mucosal response.

Dissolving Microneedles for Intradermal Vaccination against Shigellosis

“…In recent years, there has been an increasing requirement for alternative vaccine delivery systems to avoid the use of injectable devices, which need trained personnel for their administration and may require specialized storage and transport conditions [24]. This is especially important in the developing world, where numerous infectious diseases are endemic [25].…”

“…This is especially important in the developing world, where numerous infectious diseases are endemic [25]. Furthermore, from an immunological point of view, although injectable vaccines are capable of eliciting robust systemic responses, they sometimes suffer from a lack of mucosal protection, which is essential to protect against specific infectious agents, such as enteropathogens [24]. The main alternative routes of vaccine delivery without needles capable of eliciting both mucosal and systemic immune responses are mucosal and intradermal ones [26].…”

Escape or Fight: Inhibitors in Hemophilia A

“…Oral administration of antigens presents different advantages, including low costs, stability and self-administration, avoiding the discomfort of injectable preparations. This approach can be used for both immunization and tolerance induction according to the correct administration regimen (timing and dosage) (107). For these reasons, bioencapsulation of FVIII in plant cells and its oral administration would be an ideal alternative to current ITI protocols, giving the possibility of avoiding frequent injections (up to twice a day according to the protocol) and treatmentrelated high costs.…”

“…For these reasons, bioencapsulation of FVIII in plant cells and its oral administration would be an ideal alternative to current ITI protocols, giving the possibility of avoiding frequent injections (up to twice a day according to the protocol) and treatmentrelated high costs. One of the disadvantages of this strategy is that production of glycosylated antigens is not suitable in plastids (107), which are used to achieve high FVIII antigens production (42). Additional studies are necessary in order to better evaluate the efficacy of and the optimal dosage for this strategy in tolerance induction.…”

Edible Vaccines: Promises and Challenges

“…Particularly in the developing world, edible vaccine offer exciting possibilities of reducing the burden of diseases such as hepatitis b and diarrhoea where storing and administering vaccine are often major problems. For production of edible vaccines or antibodies, it is desirable to select suitable plants, algae, yeast, insect cells and lactic acid bacteria whose products are consumed raw to avoid degradation [12,13].…”