CD11c⁺ cells primed with unrelated antigens facilitate an accelerated immune response to influenza virus in mice.

Recent evidence suggests that an individual's unique history and sequence of exposures to pathogens and antigens may dictate downstream immune responses to disparate antigens. We show that the i.n. delivery of nonreplicative virus-like particles (VLPs), which bear structural but no antigenic similarities to respiratory pathogens, acts to prime the lungs of both C56BL/6 and BALB/c mice, facilitating heightened and accelerated primary immune responses to high-dose influenza challenge, thus providing a nonpathogenic model of innate imprinting. These responses correspond closely to those observed following natural infection with the opportunistic fungus, Pneumocystis murina, and are characterized by accelerated antigen processing by DCs and alveolar macrophages, an enhanced influx of cells to the local tracheobronchial lymph node, and early upregulation of T-cell co-stimulatory/adhesion molecules. CD11c⁺ cells, which have been directly exposed to VLPs or Pneumocystis are necessary in facilitating enhanced clearance of influenza virus, and the repopulation of the lung by Ly-6C⁺ precursors relies on CCR2 expression. Thus, immune imprinting 72 h after VLP-priming, or 2 weeks after Pneumocystis-priming is CCR2-mediated and results from the enhanced antigen processing, maturation, and trafficking abilities of DCs and alveolar macrophages, which cause accelerated influenza-specific primary immune responses and result in superior viral clearance.

Regulation of IFN-γ by IL-13 dictates susceptibility to secondary postinfluenza MRSA pneumonia.

Superinfection in mice at day 7 postinfluenza infection exacerbates bacterial pneumonia at least in part via downstream effects of increased IFN-γ signaling. Here we show that up to 3 days postinfluenza infection, mice have reduced susceptibility to superinfection with methicillin-resistant Staphylococcus aureus (MRSA), but that superinfection during that time exacerbated influenza disease. This was due to IL-13 signaling that was advantageous for resolving MRSA infection via inhibition of IFN-γ, but was detrimental to the clearance of influenza virus. However, if superinfection did not occur until the near resolution of influenza infection (day 7), IL-13 signaling was inhibited, at least in part by upregulation of IL-13 decoy receptor (IL-13Rα2), which in turn caused increases in IFN-γ signaling and exacerbation of bacterial infection. Understanding these cytokine sequelae is critical to development of immunotherapies for influenza-MRSA coinfection since perturbations of these sequelae at the wrong time could increase susceptibility to MRSA and/or influenza.

The Role of Altruistic Values in Motivating Underrepresented Minority Students for Biomedicine.

Understanding how cultural values influence undergraduate students' science research experiences and career interest is important in efforts to broaden participation and to diversify the biomedical research workforce. The results from our prospective longitudinal study demonstrated that underrepresented minority student (URM) research assistants who see the altruistic value of conducting biomedical research feel more psychologically involved with their research over time, which, in turn, enhances their interest in pursuing a scientific research career. These altruistic motives are uniquely influential to URM students and appear to play an important role in influencing their interest in scientific research careers. Furthermore, seeing how research can potentially affect society and help one's community does not replace typical motives for scientific discovery (e.g., passion, curiosity, achievement), which are important for all students. These findings point to simple strategies for educators, training directors, and faculty mentors to improve retention among undergraduate URM students in biomedicine and the related sciences.

Virus-like particle-induced protection against MRSA pneumonia is dependent on IL-13 and enhancement of phagocyte function.

The importance of the priming of the lung environment by past infections is being increasingly recognized. Exposure to any given antigen can either improve or worsen the outcome of subsequent lung infections, depending on the immunological history of the host. Thus, an ability to impart transient alterations in the lung environment in anticipation of future insult could provide an important novel therapy for emerging infectious diseases. In this study, we show that nasal administration of virus-like particles (VLPs) before, or immediately after, lethal challenge with methicillin-resistant Staphylococcus aureus (MRSA) of mice i) ensures complete recovery from lung infection and near absolute clearance of bacteria within 12 hours of challenge, ii) reduces host response-induced lung tissue damage, iii) promotes recruitment and efficient bacterial clearance by neutrophils and CD11c(+) cells, and iv) protects macrophages from MRSA-induced necrosis. VLP-mediated protection against MRSA relied on innate immunity. Complete recovery occurred in VLP-dosed mice with severe combined immunodeficiency, but not in wild-type mice depleted of either Ly6G(+) or CD11c(+) cells. Early IL-13 production associated with VLP-induced CD11c(+) cells was essential for VLP-induced protection. These results indicate that VLP-induced alteration of the lung environment protects the host from lethal MRSA pneumonia by enhancing phagocyte recruitment and killing and by reducing inflammation-induced tissue damage via IL-13-dependent mechanisms.

Pneumocystis elicits a STAT6-dependent, strain-specific innate immune response and airway hyperresponsiveness.

It is widely held that exposure to pathogens such as fungi can be an agent of comorbidity, such as exacerbation of asthma or chronic obstructive pulmonary disease. Although many studies have examined allergic responses to fungi and their effects on pulmonary function, the possible pathologic implications of the early innate responses to fungal pathogens have not been explored. We examined early responses to the atypical fungus Pneumocystis in two common strains of mice in terms of overall immunological response and related pathology, such as cell damage and airway hyperresponsiveness (AHR). We found a strong strain-specific response in BALB/c mice that included recruitment of neutrophils, NK, NKT, and CD4 T cells. This response was accompanied by elevated indicators of lung damage (bronchoalveolar lavage fluid albumin and LDH) and profound AHR. This early response was absent in C57BL/6 mice, although both strains exhibited a later response associated with the clearance of Pneumocystis. We found that this AHR could not be attributed exclusively to the presence of recruited neutrophils, NKT, NK, or CD4 cells or to the actions of IFN-γ or IL-4. However, in the absence of STAT6 signaling, AHR and inflammatory cell recruitment were virtually absent. Gene expression analysis indicated that this early response included activation of several transcription factors that could be involved in pulmonary remodeling. These results show that exposure to a fungus such as Pneumocystis can elicit pulmonary responses that may contribute to morbidity, even without prior sensitization, in the context of certain genetic backgrounds.

Pneumocystis infection in an immunocompetent host can promote collateral sensitization to respiratory antigens.

Infection with the opportunistic fungal pathogen Pneumocystis is assumed to pass without persistent pathology in immunocompetent hosts. However, when immunocompetent BALB/c mice were inoculated with Pneumocystis, a vigorous Th2-like pulmonary inflammation ensued and peaked at 14 days postinfection. This coincided with a 10-fold increase in the number of antigen-presenting cells (APCs) in the lung, and these cells were capable of presenting antigen in vitro, as well as greater uptake of antigen in vivo. When mice were presented with exogenous antigen at the 14-day time point of the infection, they developed respiratory sensitization to that antigen, in the form of increased airway hyperresponsiveness upon a later challenge, whereas mice not infected but presented with antigen did not. Like other forms of collateral sensitization, this response was dependent on interleukin-4 receptor signaling. This ability to facilitate sensitization to exogenous antigen has been previously reported for other infectious disease agents; however, Pneumocystis appears to be uniquely capable in this respect, as a single intranasal dose without added adjuvant, when it was administered at the appropriate time, was sufficient to initiate sensitization. Pneumocystis infection probably occurs in most humans during the first few years of life, and in the vast majority of cases, it fails to cause any overt direct pathology. However, as we show here, Pneumocystis can be an agent of comorbidity at this time by facilitating respiratory sensitization that may relate to the later development or exacerbation of obstructive airway disease.

Type-I IFN signaling suppresses an excessive IFN-gamma response and thus prevents lung damage and chronic inflammation during Pneumocystis (PC) clearance in CD4 T cell-competent mice.

Immune-reconstitution after highly active antiretroviral therapy (HAART) is often incomplete, and some HIV-infected individuals fail to regenerate type-I interferon (IFN)-producing pDCs. We recently demonstrated that during Pneumocystis (PC) infection in CD4 T cell-competent mice the absence of type-I IFN signaling results in chronic pulmonary inflammation and fibrosis despite clearance. Because the mechanisms involved are poorly understood, we further characterized the role of type-I IFN signaling in immune responses to PC. We show that type-I IFN signaling around day 7 postinfection is critical to the outcome of inflammation. Microarray analysis of pulmonary CD11c(+) cells revealed that at day 7 post infection, wild-type cells up-regulated type-I IFN-responsive genes as well as SOCS1, which is a critical negative-regulator of type-I IFN and IFN-gamma signaling. This was associated with an eosinophilic lung inflammation, PC clearance, and complete restitution. However, pulmonary CD11c(+) cells from IFNAR(-/-) mice demonstrated increased tumor necrosis factor (TNF)-alpha production and lacked SOCS1-induction at day 7. This was followed by a transient lymphocytic and IFN-gamma response before switching to a chronic eosinophilic inflammation of the lung. Early neutralization of TNF-alpha did not prevent chronic inflammation in IFNAR(-/-) mice, but treatment with an anti-IFN-gamma antibody did. We propose that during PC lung infection type-I IFNs induce SOCS1-associated regulatory mechanisms, which prevent excessive IFN-gamma-mediated responses that cause chronic lung damage. Therefore, partial immune-reconstitution in AIDS, attributable to reduced type-I IFN actions, might disrupt regulatory aspects of inflammation, causing unexplained chronic pulmonary complications as seen in some patients during HAART.

Influenza virus infection decreases tracheal mucociliary velocity and clearance of Streptococcus pneumoniae.

Influenza virus infections increase susceptibility to secondary bacterial infections, such as pneumococcal pneumonia, resulting in increased morbidity and mortality. Influenza-induced tissue damage is hypothesized to increase susceptibility to Streptococcus pneumoniae infection by increasing adherence to the respiratory epithelium. Using a mouse model of influenza infection followed by S. pneumoniae infection, we found that an influenza infection does not increase the number of pneumococci initially present within the trachea, but does inhibit pneumococcal clearance by 2 hours after infection. To determine whether influenza damage increases pneumococcal adherence, we developed a novel murine tracheal explant system to determine influenza-induced tissue damage and subsequent pneumococcal adherence. Murine tracheas were kept viable ex vivo as shown by microscopic examination of ciliary beating and cellular morphology using continuous media flow for up to 8 days. Tracheas were infected with influenza virus for 0.5-5 days ex vivo, and influenza-induced tissue damage and the early stages of repair to the epithelium were assessed histologically. A prior influenza infection did not increase pneumococcal adherence, even when the basement membrane was maximally denuded or during the repopulation of the basement membrane with undifferentiated epithelial cells. We measured mucociliary clearance in vivo and found it was decreased in influenza-infected mice. Together, our results indicate that exposure of the tracheal basement membrane contributes minimally to pneumococcal adherence. Instead, an influenza infection results in decreased tracheal mucociliary velocity and initial clearance of pneumococci, leading to an increased pneumococcal burden as early as 2 hours after pneumococcal infection.

Role of CD4+ and CD8+ T cells in clearance of primary pulmonary infection with Coxiella burnetii.

The mechanisms of the primary adaptive immune response to Coxiella burnetii are not well known. Following inoculation of the lungs with C. burnetii Nine Mile phase I (NMI), SCID mice developed pneumonia and splenomegaly and succumbed to infection, whereas wild-type mice cleared the infection by 24 days. SCID mice reconstituted with either CD4+ T cells or CD8+ T cells alone were able to control the infection, indicating that the presence of either type of T cells was sufficient to control infection, and B cells were not necessary for primary immunity. Similarly, wild-type mice depleted of either CD4+ T cells or CD8+ T cells controlled infections in their lungs, but these mice were highly susceptible if they were depleted of both types of T cells. However, compared to CD4+ T-cell-dependent protection, CD8+ T-cell-dependent protection resulted in less inflammation in the lungs and less growth of bacteria in the spleens.

CD4 effector T cell subsets in the response to influenza: heterogeneity, migration, and function.

The immune response of naive CD4 T cells to influenza virus is initiated in the draining lymph nodes and spleen, and only after effectors are generated do antigen-specific cells migrate to the lung which is the site of infection. The effector cells generated in secondary organs appear as multiple subsets which are a heterogeneous continuum of cells in terms of number of cell divisions, phenotype and function. The effector cells that migrate to the lung constitute the more differentiated of the total responding population, characterized by many cell divisions, loss of CD62L, down-regulation of CCR7, stable expression of CD44 and CD49d, and transient expression of CCR5 and CD25. These cells also secrete high levels of interferon gamma and reduced levels of interleukin 2 relative to those in the secondary lymphoid organs. The response declines rapidly in parallel with viral clearance, but a spectrum of resting cell subsets reflecting the pattern at the peak of response is retained, suggesting that heterogeneous effector populations may give rise to corresponding memory populations. These results reveal a complex response, not an all-or-none one, which results in multiple effector phenotypes and implies that effector cells and the memory cells derived from them can display a broad spectrum of functional potentials.

Alveolar macrophage-mediated killing of Pneumocystis carinii f. sp. muris involves molecular recognition by the Dectin-1 beta-glucan receptor.

Innate immune mechanisms against Pneumocystis carinii, a frequent cause of pneumonia in immunocompromised individuals, are not well understood. Using both real time polymerase chain reaction as a measure of organism viability and fluorescent deconvolution microscopy, we show that nonopsonic phagocytosis of P. carinii by alveolar macrophages is mediated by the Dectin-1 beta-glucan receptor and that the subsequent generation of hydrogen peroxide is involved in alveolar macrophage-mediated killing of P. carinii. The macrophage Dectin-1 beta-glucan receptor colocalized with the P. carinii cyst wall. However, blockage of Dectin-1 with high concentrations of anti-Dectin-1 antibody inhibited binding and concomitant killing of P. carinii by alveolar macrophages. Furthermore, RAW 264.7 macrophages overexpressing Dectin-1 bound P. carinii at a higher level than control RAW cells. In the presence of Dectin-1 blockage, killing of opsonized P. carinii could be restored through FcgammaRII/III receptors. Opsonized P. carinii could also be efficiently killed in the presence of FcgammaRII/III receptor blockage through Dectin-1-mediated phagocytosis. We further show that Dectin-1 is required for P. carinii-induced macrophage inflammatory protein 2 production by alveolar macrophages. Taken together, these results show that nonopsonic phagocytosis and subsequent killing of P. carinii by alveolar macrophages is dependent upon recognition by the Dectin-1 beta-glucan receptor.

Melanoma and lymphocyte cell-specific targeting incorporated into a heat shock protein cage architecture.

Protein cages, including viral capsids, ferritins, and heat shock proteins (Hsps), can serve as nanocontainers for biomedical applications. They are genetically and chemically malleable platforms, with potential as therapeutic and imaging agent delivery systems. Here, both genetic and chemical strategies were used to impart cell-specific targeting to the Hsp cage from Methanococcus jannaschii. A tumor vasculature targeting peptide was incorporated onto the exterior surface of the Hsp cage. This protein cage bound to alpha(v)beta(3) integrin-expressing cells. Cellular tropism was also imparted by conjugating anti-CD4 antibodies to the exterior of Hsp cages. These Ab-Hsp cage conjugates specifically bound to CD4(+) cells. Protein cages have the potential to simultaneously incorporate multiple functionalities, including cell-specific targeting, imaging, and therapeutic agent delivery. We demonstrate the simultaneous incorporation of two functionalities, imaging and cell-specific targeting, onto the Hsp protein cage.

Neutrophils and inducible nitric-oxide synthase are critical for early resistance to the establishment of Tritrichomonas foetus infection.

Tritrichomonas foetus is the cause of trichomoniasis in cattle. Severe infection is often associated with heavy neutrophil and macrophage accumulation, although it is not known how this response protects during early parasite colonization. The goal of this study was to examine the effects of an early host response upon initial T. foetus colonization within the murine reproductive tract. Mice depleted of neutrophils before T. foetus infection had a significantly higher parasite burden within the reproductive tract compared with mock-depleted control mice. Additionally, gp91(phox-/-)/ iNOS(-/-), and iNOS(-/-) mice had substantially larger parasite burdens than C57BL/6 control mice, whereas gp91l(Phox-/-) mice had similar parasite burden to C57BL/6 control mice. Interestingly, phorbol 12-myristate 13-acetate-stimulated neutrophils and macrophages isolated from all groups of mice were unable to kill T. foetus in vitro. However, macrophages isolated from gp91l(phox-/-) and C57BL/6 mice stimulated with interferon-gamma and lipopolysaccharide were able to kill T. foetus in vitro, whereas macrophages isolated from gp91(phox(-/-)/ iNOS(-/-) and iNOS(-/-) mice were unable to kill T. foetus, suggesting the ability of macrophages to produce reactive nitrogen species but not reactive oxygen species (ROS) is critical for parasite killing during early infection in vivo and in vitro. Additionally, neutrophils seem to control early dissemination of T. foetus throughout the reproductive tract, although production of ROS is not critical for this process.

Bronchoalveolar immune defense in cattle exposed to primary and secondary challenge with bovine viral diarrhea virus.

To evaluate immune defense mechanisms against bovine viral diarrhea virus (BVDV), four calves received primary and secondary intrabronchial infections with the cytopathic, type I Singer strain of BVDV. The cellular and humoral responses to these site-specific infections with BVDV were monitored by sequential bronchoalveolar lavages (BAL) conducted prior to infection (day 0, non-infected controls) and on days 4, 7, 10, 17 (day 31, secondary infection), 35, 38, 41, 48 and 62 post-infection. Peak quantities of BVDV were recovered from BAL on day 4. BVDV clearance from the lung was complete between days 17 and 31. Immune clearance of BVDV from the lower airways upon secondary infection was swift, within 4 days, and sustained throughout a 1-month period. Total numbers of BAL CD4(+) and CD8(+) T-lymphocytes increased >200-fold by day 10, and increased to levels >70-fold higher than background by 4 days after a secondary BVDV infection. gammadelta(+) T-lymphocytes increased 100-fold by day 7 and remained at levels at least 10-fold higher than pre-infection throughout the study. B-lymphocytes increased to levels 30-fold greater than pre-infection levels by day 10, and further increased to levels 100-fold higher following secondary BVDV infection. Activation (defined by the phenotype CD25(+)/CD62L(-)) and memory (defined by the phenotype CD45RO(+)/CD45R(-)) profiles of lymphocytes in the lower airways were characterized. Activated subpopulations of CD4(+) and CD8(+) cells increased nearly 300- and 150-fold, respectively, by day 10, and to levels 100- and 50-fold 4 days after the secondary infection. Memory subpopulations of CD4(+) and CD8(+) cells increased to levels 170- and 120-fold, respectively, by day 10, and to levels approximately 400- and 300-fold, respectively, 7 days after the secondary infection. The primary antibody response consisted of increased titers of anti-BVDV-specific IgA in bronchoalveolar lavage fluid (BALF). A strong secondary antibody response with high levels of anti-BVDV-specific IgA and IgG in BALF before day 4 post-secondary BVDV infection, likely contributed, along with cellular defenses, to the rapid clearance of virus from the lung upon secondary exposure. These results demonstrate that primary infection of the bovine lung with BVDV initiates cell-mediated immune responses capable of clearing the virus within 2-3 weeks. Furthermore, populations of immune-activated and memory T-lymphocytes, combined with BVDV-specific antibody production, contribute to rapid BVDV clearance upon secondary exposure to the virus.

Antiviral memory T-cell responses in the lung.

Recent studies have identified distinct populations of memory T cells that persist in the lungs following respiratory virus infections, and contribute to the control of secondary virus infections. Here we discuss the establishment, maintenance and recall of memory T cells in the lung.

Cryptosporidium parvum infection in gene-targeted B cell-deficient mice.

The importance of B cells in host resistance to, and recovery from, Cryptosporidium parvum infection was examined in gene-targeted B cell-deficient (muMT-/-) mice. Neonatal muMT-/- mice infected with C. parvum at 5 days of age completely cleared the infection by day 20 PI. The kinetics of infection and clearance were similar to those seen with age-matched C57BL/6 control mice. Furthermore, B cells were not required to clear existing C. parvum infection in adult mice. Reconstitution of persistently infected Rag-1-/- adult mice with spleen cells from muMT-/- donor mice resulted in significant reduction of infection, as in the results seen with spleen cells from C57BL6 donors. These findings indicate clearly that B cells are not essential for host resistance to, and recovery from, C. parvum infection in mice.

Biomimetic antigenic nanoparticles elicit controlled protective immune response to influenza.

Here we present a biomimetic strategy toward nanoparticle design for controlled immune response through encapsulation of conserved internal influenza proteins on the interior of virus-like particles (VLPs) to direct CD8+ cytotoxic T cell protection. Programmed encapsulation and sequestration of the conserved nucleoprotein (NP) from influenza on the interior of a VLP, derived from the bacteriophage P22, results in a vaccine that provides multistrain protection against 100 times lethal doses of influenza in an NP specific CD8+ T cell-dependent manner. VLP assembly and encapsulation of the immunogenic NP cargo protein is the result of a genetically programmed self-assembly making this strategy amendable to the quick production of vaccines to rapidly emerging pathogens. Addition of adjuvants or targeting molecules were not required for eliciting the protective response.

Inducible bronchus-associated lymphoid tissue (iBALT) synergizes with local lymph nodes during antiviral CD4+ T cell responses.

BACKGROUND: Exposure of the lungs to an antigen or pathogen elicits the formation of lymphoid satellite islands termed inducible bronchus-associated lymphoid tissue (iBALT). However, little is known about how the presence of iBALT, induced by a stimulus unrelated to the subsequent challenge agent, influences systemic immunity in distal locations, whether it be independently, antagonistically, or synergistically. Here, we determined the kinetics of the influenza-specific responses in the iBALT, tracheobronchial lymph node (TBLN), and spleen of mice with and without pre-formed iBALT. METHODS AND RESULTS: Mice with VLP-induced iBALT or no pre-formed iBALT were challenged with influenza. We found that, as we have previously described, those mice whose lungs contained pre-formed iBALT were protected from morbidity, and furthermore, that these mice had increased dendritic cell, and alveolar macrophage accumulation in both the iBALT and TBLNs. This translated to similarly accelerated kinetics and intensified influenza-specific CD4(+), but not CD8(+) T cell responses in the iBALT, TBLN, and spleen. This expansion was then followed by a more rapid T cell contraction in all lymphoid tissues in the mice with pre-formed iBALT. CONCLUSIONS: Thus, iBALT itself may not be responsible for the accelerated primary immune response we observe in mice with pre-formed iBALT, but may contribute to an overall accelerated local and systemic primary CD4(+), but not CD8(+) T cell response. Furthermore, less damaging immune responses observed in mice with pre-formed iBALT may be due to a quicker contraction of CD4(+) T cell responses in both local and systemic secondary lymphoid tissue.

Resident alveolar macrophages are susceptible to and permissive of Coxiella burnetii infection.

Coxiella burnetii, the causative agent of Q fever, is a zoonotic disease with potentially life-threatening complications in humans. Inhalation of low doses of Coxiella bacteria can result in infection of the host alveolar macrophage (AM). However, it is not known whether a subset of AMs within the heterogeneous population of macrophages in the infected lung is particularly susceptible to infection. We have found that lower doses of both phase I and phase II Nine Mile C. burnetii multiply and are less readily cleared from the lungs of mice compared to higher infectious doses. We have additionally identified AM resident within the lung prior to and shortly following infection, opposed to newly recruited monocytes entering the lung during infection, as being most susceptible to infection. These resident cells remain infected up to twelve days after the onset of infection, serving as a permissive niche for the maintenance of bacterial infection. A subset of infected resident AMs undergo a distinguishing phenotypic change during the progression of infection exhibiting an increase in surface integrin CD11b expression and continued expression of the surface integrin CD11c. The low rate of phase I and II Nine Mile C. burnetii growth in murine lungs may be a direct result of the limited size of the susceptible resident AM cell population.

A virus-like particle vaccine platform elicits heightened and hastened local lung mucosal antibody production after a single dose.

We show that a model antigen, ovalbumin (OVA), can be chemically conjugated to the exterior of a small heat shock protein (sHsp) cage that has structural similarities to virus-like particles (VLPs). OVA-sHsp conjugation efficiency was dependent upon the stoichiometry and the length of the small molecule linker utilized, and the attachment position on the sHsp cage. When conjugated OVA-sHsp was delivered intranasally to naïve mice, the resulting immune response to OVA was accelerated and intensified, and OVA-specific IgG1 responses were apparent within 5 days after a single immunizing dose, illustrating its utility for vaccine development. If animals were pretreated with a disparate VLP, P22 (a non-replicative bacteriophage capsid), before OVA-sHsp conjugate immunization, OVA-specific IgG1 responses were apparent already by 4 days after a single immunizing dose of conjugate in OVA-naïve mice. Additionally, the mice pretreated with P22 produced high titer mucosal IgA, and isotype-switched OVA-specific serum IgG. Similarly, sHsp pretreatment enhanced the accumulation of lung germinal center B cells, T follicular helper cells, and increased polymeric Ig receptor expression, priming the lungs for subsequent IgG and IgA responses to influenza virus challenge. Thus, sHsp nanoparticles elicited quick and intense antibody responses and these accelerated responses could similarly be induced to antigen chemically conjugated to the sHsp. Pretreatment of mice with P22 further accelerated the onset of the antibody response to OVA-sHsp, demonstrating the utility of conjugating antigens to VLPs for pre-, or possibly post-exposure prophylaxis of lung, all without the need for adjuvant.