Biology Reference
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Archaea domain of life [1], produced a strong humoral response in mice [2]. Archaeal
lipids exhibit radically different hydrocarbon backbones and polar head groups, as
compared to polar lipids synthesized by organisms from Eukarya and Bacteria do-
mains. Archaeal lipid backbones possess ether linkages and isoprenoid chains, mainly
phytanyl and bysphythanediyl--archaeols and caldarchaeols--in sn-2,3 enantiomeric
confi guration, in contrast to the ester linkages, straight fatty acyl chains and sn-1,2
confi guration of the glycerophospholipids from Eukarya and Bacteria domains [3].
Ether links are more resistant to acid hydrolysis than esters and the backbone/head
group cross section of archaeal lipids is almost two folds higher than that of glycero-
phospholipids from Eukarya and Bacteria domains [4, 5]. The same as liposomes,
ARC can be prepared by self association of archaeal lipids upon a small input of en-
ergy in aqueous media (thin fi lm hydration). However, beyond those apparent similari-
ties, there are remarkable structural differences: the ARC surface is highly entropic,
possessing half the surface tension than that of liposomes [5, 6] and its permeability to
protons and sodium cation is nearly one-third of that determined for liposomes; the in-
clusion of macrocyclic archaeols and caldarchaeols further impairs ARC permeability
to water and small solutes [7, 8].
Those structural features make the ARC capable of establishing unique interac-
tions with the biological environment, specifi cally eliciting adjuvancy to foreign pro-
teins upon sc administration in preclinical models by strongly stimulating both the
humoral as well as the cellular response, together with a sharp memory recall. Addi-
tionally, lipopolysaccharides are absent in Archaea [9] and, opposite to conventional
immunomodulators that usually must be included into the liposomal structure [10,
11], no toxicity has been found after parenteral administration of ARC, even at high or
multiple dosage [12, 13].
For strategic development of Third World countries, it is of crucial importance
to count on vaccines of unproblematic storage-conservation, with high resistance to
hydrolysis, oxidation and mechanical destruction, or easily reconstitutable upon ly-
ophilization [14]. Adjuvants should preferably be biodegradable, non toxic, abundant,
cheap, and available from sustainable sources. Because ARCs are suitable candidates
to fulfi ll those requirements, it is relevant to survey the adjuvant properties of ARC
made of TPL extracted from unexplored archaeal genera and species. In such context,
we determined the cytotoxicity, intracellular transit, and adjuvant activity of ARC pre-
pared with TPLs of two
H. tebenquichense
strains isolated from Argentine Patagonia,
upon two sc BSA doses followed by a single boosting inoculation in C3H/HeN mice.
Strain Isolation, Growth, and Characterization
Halophilic archaea isolated from the upper
GC
and the deeper
BM
strata grown in
enriched medium were characterized as disc-shaped (0.2 × 0.8 mm), motile Gram-
negative microorganisms. Differentially,
GC
and
BM
colonies exhibited orange-red
and reddish pigmentation, respectively. However, when grown in basal medium, a
mixture of pleomorphic rods and disc-shaped motile archaebacteria displaying unde-
fined gram staining was observed.
