Liposomal vaccine formulations as prophylactic agents: design considerations for modern vaccines

Open Access
Journal of Nanobiotechnology
*Correspondence: [e-mail] 
Department of Biomedical & Pharmaceutical Sciences and Center 
for Translational Medicine, University of Montana, 32 Campus Drive, 
Missoula, MT 59812, USA

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De Serrano and Burkhart  J Nanobiotechnol (2017) 15:83 
and as such are recognized by the first line of defense in 
the immune system, antigen presenting cells (APCs) such 
as dendritic cells (DCs), macrophages and neutrophils. 
The PAMPs are recognized by pattern recognition recep-
tors (PRRs) on the surface and in endosomes of APCs [
8
–
11
]. Vertebrates developed the adaptive immune system 
as a second line of defense that could ‘remember’ patho-
gens and fight back upon re-challenge. It is composed of 
cells such as T and B cells that employ de novo synthe-
sized antigen-specific receptors (T- and B cell receptors, 
TCRs and BCRs). TCR and BCRs are able to recognize 
pathogen-specific antigens when presented complexed 
with major histocompatibility complexes (MHC) on the 
surface of an APC. But polarization of the T or B cells 
to ensure it acts appropriately against the pathogen, 
relies on signals provided by the APC (such as co-stim-
ulatory molecules and precise cytokines) in response 
to the priming by PAMPs. These critical signals lead to 
differentiation of effector and eventually memory cells 
that are critical for driving the immune response against 
future infections with the same pathogen. While innate 
immune responses are broadly applicable and adaptive 
immune responses are antigen-specific, the two arms of 
the immune system work in close concert to mount an 
effective response to clear the pathogen.
The development of PRRs by the immune system rep-
resent a significant advancement in the fight for survival 
of the host. Therefore, an important question arises to 
that end: what type of PRRs have been discovered so far 
and which ligands (or PAMPs) do they tend to recognize? 
Some PRRs are secreted to the extracellular milieu and