Increased Immunoaccessibility of MOMP Epitopes in a Vaccine Formulated with Amphipols May Account for the Very Robust Protection Elicited against a Vaginal Challenge with Chlamydia muridarum

Abstract

There is a need to implement a vaccine to protect against Chlamydia trachomatis infections. To test a new vaccine mice were immunized with the C. muridarum native major outer membrane protein (nMOMP) solubilized with either amphipol A8-35 or the detergent Z3-14. Ovalbumin was used as a negative control and mice inoculated intranasally with C. muridarum as positive controls. Animals vaccinated with nMOMP mounted strong Chlamydia-specific humoral and cell mediated immune responses. Mice vaccinated with nMOMP/A8-35 had a higher ratio of antibodies to denatured EB over live EB, recognized more synthetic MOMP peptides and had higher neutralizing titers than sera from mice immunized with nMOMP/Z3-14. T-cell lymphoproliferative responses and levels of IFN-γ were also higher in mice vaccinated with nMOMP/A8-35 than with nMOMP/Z3-14. Following immunization animals were challenged intravaginally with C. muridarum. Based on the number of mice with positive vaginal cultures, length of vaginal shedding, total number of positive vaginal cultures and number of Chlamydia inclusion forming units recovered, nMOMP/A8-35 elicited a more robust protection than nMOMP/Z3-14. By depleting T-cells with antibodies we determined that CD4+ and not CD8+ T-cells, mediated the protection elicited by nMOMP/A8-35. Mice were subsequently mated and based on the number of pregnant mice and number of embryos, animals vaccinated with nMOMP/A8-35 or nMOMP/Z3-14 had fertility rates equivalent to the positive control group immunized with live EB and the fertility controls. In conclusion, increased accessibility of epitopes in the nMOMP/A8-35 preparation may account for the very robust protection against infection and disease elicited by this vaccine.

Labeling and Functionalizing Amphipols for Biological Applications

“…Attempts are under way to use APols to deliver either immunogens (Feinstein et al 2014; Tifrea et al 2011, 2014), in vaccine preparations, or therapeutic peptides (Fernandez et al 2014; Popot et al 2011). In order to examine how, following an injection, A8-35 distributes in the body, where it accumulates, and how it is eliminated, FAPols that absorb and emit in the red and far-red were developed, carrying as fluorophores either Atto-647 or Alexa Fluor 647.…”

“…The rationale behind tagging A8-35 particles with ODNs is twofold. First, vaccination studies show an increased protection from the pathogenic bacterium Chlamydia trachomatis when the major outer membrane protein of this organism, used as an immunogen, is trapped and stabilized in A8-35 rather than kept in detergent solution (Tifrea et al 2011, 2014). Because adjuvants are known to be most effective when co-delivered along with the antigen (Krieg 2006), it seemed worthwhile to developan APol coupled to an adjuvant, such as the CpG-1826 ODN (Krieg et al 1995), so as to ensure co-delivery of the two molecules.…”

Folding and stability of integral membrane proteins in amphipols

“…Homopolymeric 160 NAPols (Fig. 1B) are synthesized by homotelomerization of a 161 monomer carrying two glycosyl residues [77]. Heteropolymeric 162 NAPols (Fig.…”

“…[60,91,158,159] [64], which may be related to stabilization. In vaccination, better 1072 protection against a bacterial disease is obtained following immu-1073 nization against an APol-trapped than a detergent-solubilized 1074 outer TMP used as immunogen, which may be related either to 1075 its stabilization and/or to a better presentation to the immune 1076 system [53,55,161]. Also worth noting is the developing use of 1077 tagged APols for immobilizing TMPs onto solid surfaces 1078 [141,142,[162][163][164].…”

Long-Term Stability of a Vaccine Formulated with the Amphipol-Trapped Major Outer Membrane Protein from Chlamydia trachomatis

“…Specifically, when groups of mice were immunized using nMOMP or misfolded, recombinant MOMP in complex with either detergent or A8–35, the mice vaccinated with nMOMP/A8–35 complexes were significantly better protected against an intranasal challenge with C. trachomatis than the other groups of animals. This higher protection most likely results from a better preservation of the native structure of nMOMP and/or from a more efficient presentation of the antigen to the immune system, rather than from any adjuvant effect of the APol (Tifrea et al 2014, 2011). APols by themselves do not elicit antibodies [(Popot et al 2003) and unpublished observations].…”