Nano- and microparticles as adjuvants in vaccine design: Success and failure is related to host natural antibodies
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Vaccine 24 (2006) 65346541
Nano- and microparticles as adjuvanhos
myl b, R, Ramat, Rama
Bovine se pical stwere covale icity ogoldfish. Di presenanti-AP anti even sthe levels of respective natural antibodies in the host and are discussed in context of problems related to fish vaccination. The work reinforcesthe instructive role of natural antibodies in adaptive immune response. 2006 Elsevier Ltd. All rights reserved.
Keywords: Natural antibodies; Acquired antibodies; Aeromonas salmonicida
Inefficiefrequentlygenerationtides (isolanant DNAthesis, or eweakly immimmunostispecificallyantigen. Seto be an urg
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ncy of currently used conventional vaccines isdue to lack of appropriate adjuvants. The new-vaccines consisting of purified proteins and pep-ted from microorganisms, produced by recombi-technology or by direct chemical peptide syn-xpressed by relevant DNA constructs) are oftenunogenic. To be effective, these vaccines require
mulating compounds, adjuvants, which act non-to increase the immune response to a defined
arch for harmless and effective adjuvants remainsent need in modern vaccinology.
inds of the most frequently used adjuvants canished: (i) particulate (exemplified by aluminumulsions and liposomes), (ii) non-particulate (such
ding author. Tel.: +972 3 5318205; fax: +972 3 5351824.dress: email@example.com (M.S. Sinyakov).d.
as saponins, lipid A and muramyl dipeptide derivatives),and (iii) combined adjuvant compositions (Syntex adjuvantformulation, Ribi adjuvant system, and immune stimulatingcomplexes), each one exerting its own type of immune mod-ulation . The adjuvant effect of a particular system canbe mediated via three different mechanisms: (i) slow releaseof antigens at the injection site (a depot effect), (ii) target-ing of antigens to the relevant antigen-presenting cells of theimmune system, i.e. macrophages, and (iii) direct activationof cells in the immune system, e.g. bacterial adjuvants andcytokines . The former two mechanisms underlie theadjuvanticity of microparticles [4,5]. Microparticles (mostfrequently, synthetic polymer microspheres) offer a promis-ing option to oil emulsions and mineral salt adsorbents, andtheir beneficial use as carriers for vaccine delivery has beendiscussed . An association of antigen(s) with micropar-ticles can be achieved by covalent linkage or physical entrap-ment. Compared to the latter technique, where the antigenis non-covalently, physically incorporated in the micropar-ticles interior, covalent coupling offers distinct advantages:
see front matter 2006 Elsevier Ltd. All rights reserved..vaccine.2006.06.021Success and failure is related toMichael S. Sinyakov a,, Moti Dror a, Tam
Samuel Salzberg a,, Shlomo Margea Faculty of Life Sciences, Bar-Ilan University
b Department of Chemistry, Bar-Ilan UniversityReceived 9 February 2006; received in revised form 30
Available online 28 June
rum albumin (BSA) and the surface A-layer protein (AP) of an atyntly linked with polymeric nano- and microparticles, and antigenstinct albeit different levels of natural BSA and AP antibodies werebody response in mice strikingly contrasted to unresponsiveness orts in vaccine design:t natural antibodiesLublin-Tennenbaum b,amy R. Avtalion a
-Gan 52900, Israelt-Gan 52900, Israel
006; accepted 14 June 2006
rain of fish bacterial pathogen Aeromonas salmonicidaf the resulted conjugates was compared in mice andt in both animal species. Significant stimulation of the
uppression in fish. The results negatively correlate with
M.S. Sinyakov et al. / Vaccine 24 (2006) 65346541 6535
fewer antigens is required, processing and presentation byantigen-presenting cells is more efficient, stability duringstorage, and any excess of material can easily be regained. Wantigen can
The struchange mations, whicresponse elsubmicrondevelopedNanoparticducible mation accumtance of theover micro
Fish vaencountereA wide raeases. Amcausal ageand one oeconomicativated fishsalmonicid. Lackexemplifies.
We aimbased on avanticity anto nano- orwanted to cfish with ththis end, aformed in mas a modelA. salmonicessful adjwould alsoAeromonasto negativeantibodies
Sepharo(Sigma, M(Aldrich, 9(Sigma), cyaminopropmedia BHIporous ce
molecular weight cut-off (Spectra/Por), incomplete Freundsadjuvant (IFA, Sigma), ELISA microplates (Greiner),alkaline phosphatase labeled goat anti-mouse IgG (Sigma),
rophenhosphS (Mrs (Biamide
ethyol (M), Coocular w
agnetzed ese and auspenduce an waseraturwere
e magtakinere e
phatelternatP) witdiatioas a su
onjugaonjugaer ofany ao ligan
BSA sd to 2ed ovl of 2re theing re
e witheightith the use of microparticles, a very low dose ofgive rise to an optimal humoral response.cture and the properties of microparticles may
rkedly with slight alterations in production condi-h can lead to significant differences in the immuneicited. For this reason, adjuvants on the basis ofpolymeric particles, so-called nanoparticles, wereand suggested for use as potent adjuvants .les can be prepared in a physico-chemically repro-nner within narrow size limits . The informa-ulated in the last years has emphasized the impor-size and revealed the advantages of nanoparticles
spheres [21,22].ccinology faces the problems similar to thosed in vaccine design for humans and mammals.nge of pathogens is associated with fish dis-ong the bacteria, Aeromonas salmonicida, thent of furunculosis, is one of the oldest knownf the most important fish pathogens due to itslly devastating impact on both marine and cul-
. Extracellular A-layer protein (AP) of A.a has been suggested to be a major virulent factorof efficient vaccines against A. salmonicida justthe problems related to the fish vaccines design
ed to develop a candidate vaccine formulationparticulate antigen preparation with built-in adju-d consisted of the isolated AP covalently linkedmicroparticles as adjuvants. At the same time weompare the antigenicity of this conjugated AP inat in a known mammalian model, the mouse. Topreliminary search for efficient adjuvant was per-
ice with the use of bovine serum albumin (BSA)antigen. The AP was isolated from an atypical
cida strain and conjugated thereafter to the suc-uvant in expectation that the resulting conjugate
be successful in immunization of goldfish, an-susceptible fish species. The results were foundly correlate with the level of respective naturalin the host.
ls and methods
nts and chemicals
se 4B (Pharmacia Biotech Inc.), polylysineW of 50 kDa), BSA (Sigma), vinyl sulfone7%), aluminum potassium sulfate dodecahydrateanogen bromide (Fluka), 1-ethyl-3-(3-dimethyl-
yl)-carbodiimide (EDC, Pierce), complex culturebroth (Difco), bovine hemin (Sigma), molecular-
llulose ether dialysis membrane of 300 kDa
introvatiotempticlesin thAftercles wphos
A(paN-irraSDSpletioand stilledsuspefor cfor cnumbneedamin
Theaddeproce100mixtublocksalinlar wyl phosphate disodium hexahydrate (Sigmaatase substrate tablets), magnetic columns Midi
iltenyi Biotec GmbH), glycine (Sigma), salts foro-Lab Ltd., Israel), sodium dodecyl sulfate (SDS),, N,N-methylene-bis-acrylamide, N,N,N,N-lene diamine (TEMED, Sigma), -mercapto-erck), Bromo-Thymol Blue (pH range 6.07.6,massie Brilliant Blue R-250 and the standard loweight markers (Biorad) were used throughout.
sis of polymeric nanoparticles
ic nanoparticles (mNP, ca. 100150 nm) were syn-sentially according to procedure described else-. The mNP beads were coated with polylysinectivated with divinyl sulfone (DVS) in the aque-sion (at pH 10.5 and the ratio PL:DVS of 1:50) toctive double bonds onto the particles surface. Acti-carried out with constant shaking for 6 h at roome. To remove the excess of DVS, the activated par-washed thereafter (5) with 3 ml bidistilled waternetic column Midi MACS attached to a magnet.g the column off the magnet, the modified parti-xtracted from the column 10 min later with 0.1 Mbuffer (PB, pH 7.6).ively, monodispersed polyacrolein nanoparticlesh average diameter of 200 nm were prepared byn of acrolein in aqueous solution in the presence ofrfactant as described elsewhere . Upon com-
polymerization, the excess of the free monomerant was removed by extensive dialysis against dis-. The concentration of the paNP beads in the finalwas estimated to be 1.9% (w/v) when preparedtion with BSA, and 3.2% (w/v) when preparedtion with AP. This type of beads contains a largereactive functional aldehyde groups and does notdditional activation prior to use for coupling ofds.
conjugated with nanoparticles (BSA-mNPaNP)t immobilization of BSA on the activated mNPout at room temperature with constant shaking.
olution containing 5 mg BSA in 0.3 ml PB wasml mNP suspension and reaction was allowed toernight. To block the residual functional groups,% glycine solution were added to the reactionreafter. The unbound BSA and the excess of theagent were removed by extensive dialysis againstthe use of dialysis bags with 300 kDa molecu-cutoff. Completion of removal of the unbound
6536 M.S. Sinyakov et al. / Vaccine 24 (2006) 65346541
BSA was verified by SDS-polyacrylamide gel electrophore-sis (SDS-PAGE) of the final suspension using 10% separat-ing gel run under reducing conditions.