Table 3.

Particulate delivery systems as vaccine adjuvant.

Adjuvant type	Representing examples	General description	Mechanism of action	Advantages	Disadvantages
Particulate delivery vehicle	ISCOM	It contains a triterpenoid saponins obtained from Quillaia saponins, a sterol and optionally a phospholipid. The saponins are Quil A or QS-21	1.Generate CTL response, induce cytokines 2.Directly phagocytosed by macrophages	Induces strong immune response	1.Severe pain at the site of injection 2.Severe toxicity includes severe haemolysis, granulomas
	Liposomes	Contains synthetic phospholipids. Liposomes based hepatitis A vaccine approved in Europe	Fuse with cell membrane of macrophages, enable antigen in to the cyto plasma, enter MHC class I path way and activate CD8 CTL response	Induces strong immune response	1.Manufacturing difficulties due to stability 2.High cost 3.Severe pain at the site of injections
	Polymeric microparticle	1.It is made by biodegradable polymers 2.Antigens encapsulated inside the microparticles 3.It is considered as next generation of adjuvants 4.Potential for single shot vaccines	1.Long term depot effect from weeks to months 2.Pulsatile release of antigens 3.Target to antigen presenting cells	1.It can mimic the priming and boosting effect of conventional vaccine 2.Potential for single shot vaccines and can reduces the cost of vaccination	1.Issues on stability of antigens during micro encapsulation and storage 2.Issues on dose optimization