Preparation and in-vitro characterization of alginate microspheres incorporating leptospiral antigens as a delivery system and adjuvant

Document Type: Original Articles

Authors

1 Department of Microbiology, Faculty of Basic Sciences, Islamic Azad University, Karaj Branch, Karaj, Iran

2 Department of Microbiology, Razi Vaccine and Serum Research Institute, Karaj, Iran

3 Department of Venom and Human Sera, Razi Vaccine and Serum Research Institute, Karaj, Iran

Abstract

Leptospirosis is one of the most prevalent zoonotic diseases worldwide. Currently, multivalent whole-cell leptospiral vaccines can induce protection against leptospirosis. Therefore, preparation and formulation of new generations of vaccines that can stimulate long-term immunity for leptospirosis control are essential. The aim of this study was to prepare and characterize alginate microspheres as an antigen delivery system for immunization against leptospirosis. We used five Leptospira interrogans serovars, namely, Icterohaemorrhagiae, Grippotyphosa, Serjo harjo, Pomona, and Canicola, for antigen preparation. Alginate microspheres containing leptospiral antigen (LA) were prepared by an emulsification method and evaluated with respect to morphology, size distribution, loading efficiency (LE), loading capacity (LC), and release profile. The effects of concentration of alginate and emulsifiers and stirring rate on characteristics of microspheres were investigated. The optimal condition parameters for the preparation of LA-loaded alginate microspheres were estimated. The optimum concentrations obtained for alginate and emulsifiers were 3.65% (w/v), Span 80 (0.24% w/v), and Tween 80 (3.85% w/v), respectively. Moreover, the appropriate homogenization rate was 500 rpm. Our results showed mean particle size of 200 μm, 97.41% LE, and 8% LC for the microspheres. Sufficient release profile was observed for in-vitro release test of LA from alginate microspheres over an extended period of time (216 hour). Therefore, alginate microspheres technologically seem to be a promising antigen delivery system for leptospiral vaccine.

Keywords

Main Subjects


Article Title [French]

Préparation et caractérisation in-vitro des microsphères d’alginate chargées d’antigènes leptospiraux en tant que système de délivrance et adjuvant

Abstract [French]

La leptospirose est l’une des zoonoses les plus courantes à travers le monde. Actuellement, la protection contre la leptospirose peut être induite par un vaccin constitué de germes leptospiraux entiers. De ce fait, la préparation et la formulation d’une nouvelle génération de vaccins capable de favoriser une immunité à long terme sont essentielles pour le contrôle de cette maladie. L’objectif de cette étude était de préparer et caractériser un nouveau système de délivrance composé de microsphères d’alginate pour l’immunisation contre la leptospirose. Pour la préparation des antigènes, 5 sérotypes de Leptospira interrogans à savoir Icterohaemorrhagiae, Grippotyphosa, Serjo harjo, Pomona, et Canicola on été utilisés. Les microsphères d’alginate contenant les antigènes leptospiraux (AL) ont été préparées par émulsification et ensuite analysées en termes de morphologie, granulométrie, efficacité de chargement (EC), capacité de chargement (CC) et profil de libération. De plus, l’influence des concentrations en alginate et en émulsifiant a également été étudiée. Enfin, les conditions optimales de préparation pour les microsphères d’alginate chargées d’AL ont été déterminées. Selon nos résultats, les concentrations optimales de préparation étaient respectivement de 3,65% p/v (pourcentage de poids par volume) d’alginate dans l’émulsifiant, 0,24% v/v de Span 80 et 3,85% v/v de Tween 80. De plus, le taux d’homogénéisation approprié a été obtenu à 500 rpm. La taille moyenne des particules générées était de 200 nm avec un EC de 97,41% et un CC de 8%. Les testes de libération des AL à partir des microsphères d’alginate montrent un profil de libération étendu sur une période prolongée de 216 heures. Pa conséquent, sur le plan technique, les microsphères d’alginate semblent représenter un système de délivrance prometteur pour le vaccin leptospiral.

Keywords [French]

  • Leptospira spp
  • Antigène leptospiral
  • Alginate
  • Microsphères
  • Délivrance d’antigène
  • Immunisation
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