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

Table 4 Promising formulations for the treatment of bacterial infections
Cell cultures and no vaccination in animal models were employed
N/A not applicable
Lipid(s) and sterol used
Bacteria or disease Cell line/animal model 
used
Administration route Promising liposome 
formulation
References
PC/PG/Chol, PC/PG/Chol/
Man-PE, PC/PS/Chol, PC/
DMTAP/Chol
Meningitis
Monocyte-derived human 
DCs and murine bone 
marrow-derived DCs
N/A
PC/PG/Chol/Man-PE and 
PC/DMTAP/Chol
[
94
]
PC/Chol/SA, PC/Chol/PA and 
PC/Chol
Diphteria toxin
BALB/c, C57BL/6 and ddY 
mice; P815, P13.1 and 
CD8OVA cells
Subcutaneous
PC/Chol/SA
[
93
]
DOTAP and DOPC
Melioidosis
Neutrophils and splenocytes 
from BALB/c mice
Intramuscular
DOTAP
[
2
]
DOPE/DOTAP
E. coli
Mouse embryonic fibroblasts 
(MEF) and RAW 264.7 
macrophages
N/A
DOPE/DOTAP
[
92
]
DDA/Chol/Man-C6-Chol and 
DDA/Chol
E. coli
DC 2.4 cells
N/A
DDA/Chol/Man-C6-Chol
[
19
]

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Page 13 of 23
De Serrano and Burkhart  J Nanobiotechnol (2017) 15:83 
inoculation. Vaccinated mice challenged with C. albicans 
presented lower CFUs (110 ± 38 × 10
3
CFU/g of vaginal 
tissue) when compared to non-mannan vaccine approach 
(240 ± 44 × 10
3
CFU/g of vaginal tissue). Both article 
demonstrated the capacity of the vaccine to protect at 
local or systemic infections of C. albicans.
Further studies investigated zwitterionic and cationic 
liposomes utilizing ribosomes and recombinant Hsp90 
protein as antigens from C. albicans [
108
–
110
]. Eck-
stein et al. prepared anionic DMPC:DMPG liposomes 
co-lyophilized with RNA obtained from cell lysates of C. 
albicans cultures or by lipid film formation. Mice protec-
tion in a subcutaneous vaccination (60% survival) against 
the fungal challenge demonstrated the effectiveness of 
the vaccine prepared by the co-lyophilization method 
in the presence of C. albicans ribosomes. Subsequently, 
neutrally charged metalloliposomes with incorporated 
recombinant Hsp90 (heat shock) protein from C. albi-
cans were developed. Nickel-chelating liposomes were 
prepared with EPC and 1,2-dioleoyl-sn-glycero-3-[(N-
(5-amino-1-carboxypentyl)iminodiacetic acid)succinyl] 
(nickel salt) (DOGS-NTS-Ni) at molar ratios of 95:5. 
A non-pyrogenic MDP was used as an adjuvant in the 
liposomal system and the protein was surface attached 
by metallochelating bonds. DCs interacted with the 
liposomes and phagocytosed the nanoparticles in vitro. 
T
H
1 and T
H
2 immune responses were induced after 
intradermal mice vaccination in comparable levels to the 
Freund’s complete adjuvant vaccine. Following the pre-
vious report, Knotigová et al. employed nickel-chelating 
liposomes with different MDP-derivatives (norAbuMDP/
GMDPs) and tested their adjuvant vaccine potential 
[
110
]. Also, Hsp90 from C. albicans was employed as the 
model antigen. Adaptive and innate immune responses 
were induced by the developed vaccine systems in intra-
dermal vaccinated rabbits and mice.
Recently, cationic liposomes studies incorporated 
cell wall surface proteins (CWSPs) of C. albicans and 
their immunostimulatory properties analyzed during 
subcutaneous administration [
111
, 
112
]. Both studies 
employed DDA:monooleoylglycerol (MO) at 33:67 molar 
ratio. Liposomes were not toxic to macrophages and were 
internalized within 20 min of exposure. In the first study, 
immunized mice displayed strong humoral- and cell-
mediated immune responses. Antibodies were produced 
against cell wall proteins Cht3p and Xog1p. In the second 
report, two CWSP-loaded cationic liposomal formula-
tion (ADS1 and ADS2) were tested against disseminated 
candidiasis. ADS1 immunized mice presented signifi-
cantly higher levels of C. albicans antibodies, contrasting 
with the ADS2 formulation. This antibody titer produc-
tion induced the phagocytosis of the fungus. Elevated 
levels of the cytokines IL-4, IL-17 and IL-10 were signifi-
cantly higher than control groups, suggesting T
H
2, T
H
17 
and anti-inflammatory immune responses, respectively.
Future studies on fungal infections and their prophy-
lactic treatment with vaccines should be performed not 
only in C. albicans, but also other ethiological agents 
(e.g. Aspergillus). The literature review revealed a field 
with potential for growth and development of novel 
approaches to treat fungal infections, which benefit 
immunocompromised patients (elderly or HIV-seropos-
itive patients). Additionally, further studies must employ 
further cationic lipids and their effects on immune 
response induction. Studies comparing physicochemical 
properties of liposomes to treat fungal infections must 
take place to optimize the vaccine strategy and avoid 
unwanted responses and results. In the studies presented 
above, the intravenous administration was investigated 
and revealed affirmative results (~ 60% survival of mice). 
However, we recommend further studies that compare 
immunomodulatory responses against mucosal vaccine 
administration for vaginal candidiasis infections. Similar 
survival rates were observed for subcutaneous and intra-
dermal administration routes, but future studies should 
investigate a particular set of liposomes against the dif-
ferent administration to observe if survival rates are 
affected.