ISCOM: a delivery system for neonates and for mucosal administration

Discrepancies in the German Pharmacopoeia procedure for quality control of Quillaja saponin extracts

This study focused on the evaluation of Quillaja saponin extracts with the additional quality designation DAB-which means the abbreviation of the German Pharmacopoeia (Deutsches Arzneibuch). This label suggests that Quillaja saponin extracts marked in this way are of pharmacopoeial quality and thus stand out from other Quillaja saponin extracts. The DAB ninth edition listed Quillaia saponin as a reagent. According to DAB, its quality must be checked by thin-layer chromatography (TLC), and three closely spaced zones in a defined retention factor (Rf) interval specify the saponin reagent. All the Quillaja saponin extracts obtained from different manufacturers and labeled as DAB quality complied with the TLC test. However, the analysis with high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (HPLC-Q-ToF-MS) clearly showed additionally an intense peak pattern of Madhuca saponins in all measured samples. The TLC test for Mahua seed cake, which is the press residue from Madhuca longifolia, surprisingly showed the same three closely spaced zones in the defined Rf interval. The three zones could be identified as Mi-saponins from Madhuca after scraping and extracting them from the stationary phase of the TLC plate and subsequent measurement by HPLC-Q-ToF-MS. Therefore, the specification of the saponin reagent in DAB characterizes erroneously Madhuca saponins that are not listed as a saponin plant source for the saponin reagent.

Evaluation of ISCOM vaccines for mucosal immunization against hepatitis B

Immune stimulating complexes (ISCOMs) incorporating recombinant hepatitis B surface antigen (HBsAg) was prepared for induction of humoral, cellular and mucosal immunity by intranasal administration. Prepared ISCOMs were characterized for its size, shape, incorporation efficiency, zeta potential, and antigen integrity. Designed ISCOMs possessed negative zeta potential (-21.7 mV) and an average size of 44.1 nm with antigen incorporation efficiency approximately 39 %. Serum anti-HBsAg IgG titer after three high nasal doses of ISCOMs was comparable with titer recorded after alum-HBsAg administered subcutaneously. Similarly, modest but higher cellular response (cytokines level in spleen homogenates) and significantly higher secretory sIgA response in mucosal secretions was observed (P < 0.001) in case of HBsAg ISCOM vaccines. Whereas, alum-HBsAg vaccine did not elicit considerable cellular or mucosal response. Thus, ISCOMs produced humoral, mucosal, and cellular immune responses upon nasal administration although high and multidose administrations were required to elicit potent immune responses. These data demonstrate potential of ISCOMs in their use as a carrier adjuvant for nasal subunit vaccines against hepatitis B.

Nanoparticles for nasal vaccination

The great interest in mucosal vaccine delivery arises from the fact that mucosal surfaces represent the major site of entry for many pathogens. Among other mucosal sites, nasal delivery is especially attractive for immunization, as the nasal epithelium is characterized by relatively high permeability, low enzymatic activity and by the presence of an important number of immunocompetent cells. In addition to these advantageous characteristics, the nasal route could offer simplified and more cost-effective protocols for vaccination with improved patient compliance. The use of nanocarriers provides a suitable way for the nasal delivery of antigenic molecules. Besides improved protection and facilitated transport of the antigen, nanoparticulate delivery systems could also provide more effective antigen recognition by immune cells. These represent key factors in the optimal processing and presentation of the antigen, and therefore in the subsequent development of a suitable immune response. In this sense, the design of optimized vaccine nanocarriers offers a promising way for nasal mucosal vaccination.

Vaccines for tuberculosis: novel concepts and recent progress

Three-quarters of a century after the introduction of Mycobacterium bovis BCG, the first tuberculosis vaccine, new vaccines for tuberculosis are finally entering clinical trials. This breakthrough is based not only on advances in proteomics and genomics which have made the construction of new vaccines possible, but also on a greatly expanded knowledge of the immunology of tuberculosis. Here we review our current understanding of how Mycobacterium tuberculosis subverts or survives the host's immune response to cause disease and why the current vaccination strategy, which relies on BCG, is only partially successful in countering the pathogen. This provides a background for describing the new generation of vaccines designed to supplement or replace the current vaccine and the different approaches they take to stimulate immunity against M. tuberculosis.

ISCOMATRIX adjuvant: a potent inducer of humoral and cellular immune responses

ISCOMATRIX adjuvant is capable of inducing broad and potent humoral and cellular immune responses. The components are well defined and the manufacturing process is simple and robust. Many vaccines containing the ISCOMATRIX adjuvant have been tested in a range of animal models, including human and non-human primates. Strong antibody and T cell responses have been induced in these studies. The antibody response is often achieved with lesser amounts of antigen than other adjuvant systems and the maximal responses have also been reached more quickly. Both CD4+ and CD8+ T cell responses are induced with the cytotoxic T lymphocyte responses being very long lived. Additionally, ISCOMATRIX adjuvant can be used in vaccines for induction of mucosal immune responses. This review provides an overview of the immune responses that can be elicited using ISCOMATRIX vaccines and the current state of knowledge regarding the mechanism of action of this adjuvant.

Equine influenza virus infections: an update

Equine influenza is one of the most economically important contagious respiratory diseases of horses. In this paper the current state of knowledge of equine influenza virus and the most important aspects of these virus infections, e.g. epidemiology, clinical aspects, pathogenesis and pathology, immunity, diagnosis, treatment, management and vaccination, are reviewed with an emphasis on epidemiology, diagnosis and vaccinology. Many questions have remained and with the advent of improved technology new questions have arisen. Consequently, research priorities should be set in an attempt to answer them. Therefore, this review ends with some personal recommendations for important priorities for future research.

Immunostimulating complexes (ISCOMs) for nasal vaccination

The immunostimulating complex (ISCOM) is documented as a strong adjuvant and delivery system for parenteral immunization. Its effectiveness for mucosal immunization has also been proven with various incorporated antigens. Lövgren et al. were the first to demonstrate the capacity of influenza virus ISCOMs to induce mucosal immune response and protection after one comparatively low nasal dose. Further studies show that similar to Cholera toxin (CT) and Escherichia coli heat-labile toxin (LT), ISCOMs break immunological tolerance and exert strong mucosal adjuvant activity, resulting in secretory IgA and systemic immune responses. Striking is the capacity of ISCOMs to induce CTL response also after nasal administration. In contrast to CT, ISCOMs initiate mucosal as well as systemic immune responses in an IL-12 dependent manner but independently of IL-4. The recombinant B subunit of cholera toxin (rCTB) was incorporated in the same ISCOM particle to explore symbiotic effects. The IgA response to rCTB in lungs was increased 100-fold when rCTB was administered nasally in ISCOMs and more than 10-fold in the remote mucosa of the genital tract. An enhanced IgA response to a passenger antigen OVA was recorded in the remote genital tract. After i.n. administration of the envelope proteins of respiratory syncytial virus in ISCOMs, high serum antibodies were induced, almost at the same levels as those following parenteral immunization and potent IgA responses were also evoked both at the local respiratory mucosa, and in the cases tested at the distant mucosae of the genital and intestinal tracts. Similar results have also been recorded with ISCOMs containing envelope proteins from Herpes simplex virus, Influenza virus and Mycoplasma mycoides. The mucosal targeting property of envelope proteins of RSV was utilized in an HIV-gp120 RSV ISCOM formulation. After nasal administration an enhanced mucosal IgA response to gp120 was observed in the female reproductive tract. In general, antigens derived from envelope viruses or cell membranes incorporated into ISCOMs retain their biological activity and conformation, encompassing the mucosal targeting and virus neutralizing properties.

A comparison of oral and parenteral routes for therapeutic vaccination with HSV-2 ISCOMs in mice; cytokine profiles, antibody responses and protection

It is likely that recurrent infections with HSV-2 (or HSV-1) are influenced by local levels of immunity at mucosal surfaces, when virus reactivated from the latent state is infecting mucosal epithelial cells. Increasing the levels of cellular and humoral immunity through immunisation and maintaining such increased levels, may reduce establishment and spread of reactivated virus at the local site, thereby ameliorating recurrent disease symptoms. The use of HSV-2 antigens incorporated into immunostimulating complexes (ISCOMs) for immunisation of mice previously infected with HSV-2 was investigated in the present study. Prophylactic administration of HSV-2 ISCOM vaccine to mice elicits local antibody detectable in nasal washings, serum antibody and the presence of cytokines IL-2, IFN-gamma and IL-4 in supernatants from spleen cell cultures stimulated in vitro with HSV-2 antigens. Use of the same vaccine in mice infected previously with HSV-2, results in increased levels of total and subclass serum ELISA antibody and also increased levels of serum neutralising antibody. Treatment of HSV-2 infected mice with the HSV-2 ISCOM vaccine also induces higher levels of the cytokines IL-2, IFN-gamma and IL-4, in in vitro stimulated spleen cell cultures. Challenge with a lethal dose of HSV-1 showed that mice previously infected with HSV-2 and subsequently given two doses of HSV-2 ISCOMs vaccine were protected.

Equine vaccination

Equine infectious disease remains a constant and important threat to the health of domesticated horses. Vaccination plays a critical role in protecting against such disease, but at the present time the efficacy of some equine vaccination strategies is in doubt. The best strategy for resolving these concerns is an improved knowledge of the immunologic basis of successful vaccination, combined with the appropriate integration of effective vaccines into well-designed disease control policies.