• Intranasal vaccination with recombinant outer membrane protein CD and adamantylamide dipeptide as the mucosal adjuvant enhances pulmonary clearance of Moraxella catarrhalis in an experimental murine model.

      Becker, Pablo D; Bertot, Gustavo M; Souss, David; Ebensen, Thomas; Guzmán, Carlos A; Grinstein, Saúl; Virology Laboratory, Ricardo Gutiérrez Children's Hospital, Gallo 1330, 1425 Buenos Aires, Argentina. (2007-04)
      Moraxella catarrhalis causes acute otitis media in children and lower respiratory tract infections in adults and elderly. In children the presence of antibodies against the highly conserved outer membrane protein CD correlates with protection against infection, suggesting that this protein may be useful as a vaccine antigen. However, native CD is difficult to purify, and it is still unclear if recombinant CD (rCD) is a valid alternative. We performed a side-by-side comparison of the immunogenicities and efficacies of vaccine formulations containing native CD and rCD with adamantylamide dipeptide as the mucosal adjuvant. Intranasal vaccination of mice stimulated the production of high CD-specific antibody titers in sera and of secretory immunoglobulin A in mucosal lavages, which cross-recognized both antigens. While vaccination with native CD increased the number of interleukin-2 (IL-2)- and gamma interferon-producing cells, rCD mainly stimulated IL-4-secreting cells. Nevertheless, efficient bacterial clearance was observed in the lungs of challenged mice receiving native CD and in the lungs of challenged mice receiving rCD (96% and 99%, respectively). Thus, rCD is a promising candidate for incorporation in vaccine formulations for use against M. catarrhalis.
    • An SopB-mediated immune escape mechanism of Salmonella enterica can be subverted to optimize the performance of live attenuated vaccine carrier strains.

      Link, Claudia; Ebensen, Thomas; Ständner, Lothar; Déjosez, Marion; Reinhard, Elena; Rharbaoui, Faiza; Guzmán, Carlos A; Department of Vaccinology, Division of Microbiology, GBF-German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany. (2006-07)
      Salmonellae have evolved several mechanisms to evade host clearance. Here, we describe the influence on bacterial immune escape of the effector protein SopB, which is translocated into the cytosol through a type III secretion system. Wild-type bacteria, as well as the sseC and aroA attenuated mutants exerted a stronger cytotoxic effect on dendritic cells (DC) than their SopB-deficient derivatives. Cells infected with the double sseC sopB, phoP sopB and aroA sopB mutants also exhibited higher expression of MHC, CD80, CD86 and CD54 molecules, and showed a stronger capacity to process and present an I-E(d)-restricted epitope from the influenza hemagglutinin (HA) to CD4+ cells from TCR-HA transgenic mice in vitro. The incorporation of an additional mutation into the sopB locus of the attenuated sseC, phoP and aroA mutants resulted in the stimulation of improved humoral and cellular immune responses following oral vaccination. The obtained results define a new potential immune escape strategy of this important pathogen, and also demonstrate that this mechanism can be subverted to optimize the immune responses elicited using Salmonella as a live vaccine carrier.
    • Virus-like particle production with yeast: ultrastructural and immunocytochemical insights into Pichia pastoris producing high levels of the hepatitis B surface antigen.

      Lünsdorf, Heinrich; Gurramkonda, Chandrasekhar; Adnan, Ahmad; Khanna, Navin; Rinas, Ursula; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2011-06-26)
      A protective immune response against Hepatitis B infection can be obtained through the administration of a single viral polypeptide, the Hepatitis B surface antigen (HBsAg). Thus, the Hepatitis B vaccine is generated through the utilization of recombinant DNA technology, preferentially by using yeast-based expression systems. However, the polypeptide needs to assemble into spherical particles, so-called virus-like particles (VLPs), to elicit the required protective immune response. So far, no clear evidence has been presented showing whether HBsAg assembles in vivo inside the yeast cell into VLPs or later in vitro during down-stream processing and purification.