IgA levels in serum induced by i.n. immunization were around one to two orders of magnitude higher than those induced by i.d. immunization, suggesting that the NP themselves do not inherently drive IgA switching. We believe it is more likely that the route of immunization has an important role at inducing serum IgA as has been previously suggested  and . TSA HDAC supplier We speculate that gp140-specific IgA plasma cells induced in the nasal cavity may home to spleen or bone marrow. It is worth noting
that levels of gp140-specific IgG and IgA were also enhanced in the nasal cavity. This suggests that wax NP may also have utility for delivering of immunogens against respiratory pathogens. M-cells of NALT are thought to play an important role in the uptake of NP in rodents and humans and are absent in vaginal and rectal mucosa ,  and . The nasal route has been extensively studied not only for vaccination purposes , ,  and  but also for the delivery of drugs , and NP have been used nasally to induce immune responses to TT Selleck Thiazovivin  and HIV . Induction of systemic and mucosal immune responses to HIV after nasal immunization of mice  and , guinea pigs  and macaques  with HIV-gp120 Ag has been described previously.
In the latter, serum and vaginal Ab responses were induced after nasal immunization only when followed by one or two intramuscular boosts. These levels were highly enhanced in vagina after challenge with SHIV, suggesting that the nasal priming induced effective memory responses at mucosal level . In our mouse model, three nasal immunizations were enough to induce high levels of IgG and IgA in serum and vagina. It remains to be confirmed whether this immunization protocol with NP will work similarly in macaques or humans, or whether these Abs would be neutralizing.
secondly Therefore, further studies are warranted that assess homologous and heterologous immunization protocols to determine the feasibility of using these NP, as effective delivery systems of HIV Ags, in the development of mucosal vaccination in humans. Particle Science Inc has IP rights and economical interests in carnauba wax based nanoparticles mentioned in this article. This work was funded by a grant to SGUL by the Bill & Melinda Gates Foundation and the Wellcome Trust, under the Grand Challenges in Global Health Initiative. We are indebted to the Fondation Dormeur for funding of equipment used in the course of this study. We thank Professors Ralf Wagner and Hans Wolf, University of Regensburg and GENEART AG for the CN54-expressing plasmid. We thank Simon Jeffs, Sueli Vieira and Saba Hussein for work on gp140 cloning and expression. CN54-gp140 used in this study was produced under contract by Polymun Scientific GmbH. Griet Van Roey is supported by a EUROPRISE studentship funded by the European Union.