Enhanced growth of recombinant human adenovirus type 41 (HAdV-41) carrying ADP gene

Human adenovirus type 41 (HAdV-41) has the potential to be constructed as a gene transfer vector for oral vaccine or gene therapy targeting gastrointestinal tract. Block in release of progeny virus from host cell severely affects the yield during virus amplification. In this study, HAdV-5 adenovirus death protein (ADP) gene was used to replace the open reading frames (ORFs) of the HAdV-41 E3 region to construct a backbone plasmid pAdbone41ADP. Recombinant adenoviral plasmids harboring ADP and GFP genes (pAd41ADP-GFP) were generated. Plaques were formed and HAdV-41-ADP-GFP virus was rescued after transfecting pAd41ADP-GFP into the packaging cell line 293TE32. When amplified on 293TE32 cells, HAdV-41-ADP-GFP virus released to the culture medium was 10-50 times more than control virus HAdV-41-GFP, which did not carry ADP gene. The results demonstrated that incorporation of the ADP gene substantially increased the yield of recombinant HAdV-41 virus through enhancing spread of progeny virus among packaging cells.

Monitoring Therapeutic Treatments against Burkholderia Infections Using Imaging Techniques

Burkholderia mallei, the etiologic agent of glanders, are Category B select agents with biothreat potential, and yet effective therapeutic treatments are lacking. In this study, we showed that CpG administration increased survival, demonstrating protection in the murine glanders model. Bacterial recovery from infected lungs, liver and spleen was significantly reduced in CpG-treated animals as compared with non-treated mice. Reciprocally, lungs of CpG-treated infected animals were infiltrated with higher levels of neutrophils and inflammatory monocytes, as compared to control animals. Employing the B. mallei bioluminescent strain CSM001 and the Neutrophil-Specific Fluorescent Imaging Agent, bacterial dissemination and neutrophil trafficking were monitored in real-time using multimodal in vivo whole body imaging techniques. CpG-treatment increased recruitment of neutrophils to the lungs and reduced bioluminescent bacteria, correlating with decreased bacterial burden and increased protection against acute murine glanders. Our results indicate that protection of CpG-treated animals was associated with recruitment of neutrophils prior to infection and demonstrated, for the first time, simultaneous real time in vivo imaging of neutrophils and bacteria. This study provides experimental evidence supporting the importance of incorporating optimized in vivo imaging methods to monitor disease progression and to evaluate the efficacy of therapeutic treatment during bacterial infections.

Production of IL-8, IL-17, IFN-gamma and IP-10 in human astrocytes correlates with alphavirus attenuation

Venezuelan equine encephalitis virus (VEEV) is an important, naturally emerging zoonotic pathogen. Recent outbreaks in Venezuela and Colombia in 1995 indicate that VEEV still poses a serious public health threat. Astrocytes may be target cells in human and mouse infection and they play an important role in repair through gliosis. In this study, we report that virulent VEEV efficiently infects cultured normal human astrocytes, three different murine astrocyte cell lines and astrocytes in the mouse brain. The attenuation of virus replication positively correlates with the increased levels of production of IL-8, IL-17, IFN-gamma and IP-10. In addition, VEEV infection induces release of basic fibroblast growth factor and production of potent chemokines such as RANTES and MIP-1-beta from cultured human astrocytes. This growth factor and cytokine profile modeled by astrocytes in vitro may contribute to both neuroprotection and repair and may play a role in leukocyte recruitment in vivo.

Natural killer cell mediated pathogenesis determines outcome of central nervous system infection with Venezuelan equine encephalitis virus in C3H/HeN mice

TC83 is a human vaccine with investigational new drug status and is used as a prototype Venezuelan equine encephalitis virus for pathogenesis and antiviral research. Differing from other experimental models, the virus causes high titer infection in the brain and 90-100% mortality in the C3H/HeN murine model. To better characterize the susceptibility to disease development in C3H/HeN mice, we have analyzed the gene transcriptomes and cytokine production in the brains of infected mice. Our analysis indicated the potential importance of natural killer cells in the encephalitic disease development. This paper describes for the first time a pathogenic role for natural killer cells in VEEV encephalitis.

Prophylactic application of CpG oligonucleotides augments the early host response and confers protection in acute melioidosis

Prophylactic administration of CpG oligodeoxynucleotides (CpG ODNs) is known to confer protection against lethal sepsis caused by Burkholderia pseudomallei in the mouse model. The mechanisms whereby CpG regulates the innate immune response to provide protection against B. pseudomallei, however, are poorly characterized. In the present study, we demonstrate that intranasal treatment of mice with Class C CpG, results in recruitment of inflammatory monocytes and neutrophils to the lung at 48 h post-treatment. Mice infected with B. pseudomallei 48 h post-CpG treatment had reduced organ bacterial load and significantly altered cytokine and chemokine profiles concomitant with protection as compared to control animals. CpG administration reduced the robust production of chemokines and pro-inflammatory cytokines in blood, lung and spleen, observed following infection of non-treated animals. Death of control animals coincided with the time of peak cytokine production (day 1–3), while a moderate; sustained cytokine production in CpG-treated animals was associated with survival. In general, CpG treatment resulted in diminished expression of cytokines and chemokines post-infection, though IL-12p40 was released in larger quantities in CpG treated animals. In contrast to CpG-treated animals, the lungs of infected control animals were infiltrated with leukocytes, especially neutrophils, and large numbers of necrotic lesions were observed in lung sections. Therapeutic treatment of B. pseudomallei-infected animals with CpG at 24 h post-infection did not impact survival compared to control animals. In summary, protection of CpG-treated animals was associated with recruitment of inflammatory monocytes and neutrophils into the lungs prior to infection. These responses correspond with early control of bacterial growth, a dampened inflammatory cytokine/chemokine response, reduced lung pathology, and greatly increased survival. In contrast, a delay in recruitment of inflammatory cell populations, despite a robust production of pro-inflammatory cytokines, was associated with poorly controlled bacterial growth, severe lung pathology, and death of control animals.

Protective antigens against glanders identified by expression library immunization

Burkholderia are highly evolved Gram-negative bacteria that primarily infect solipeds but are transmitted to humans by ingestion and cutaneous or aerosol exposures. Heightened concern over human infections of Burkholderia mallei and the very closely related species B. pseudomallei is due to the pathogens' proven effectiveness as bioweapons, and to the increased potential for natural opportunistic infections in the growing diabetic and immuno-compromised populations. These Burkholderia species are nearly impervious to antibiotic treatments and no vaccine exists. In this study, the genome of the highly virulent B. mallei ATCC23344 strain was examined by expression library immunization for gene-encoded protective antigens. This protocol for genomic-scale functional screening was customized to accommodate the unusually large complexity of Burkholderia, and yielded 12 new putative vaccine candidates. Five of the candidates were individually tested as protein immunogens and three were found to confer significant partial protection against a lethal pulmonary infection in a murine model of disease. Determinations of peripheral blood cytokine and chemokine profiles following individual protein immunizations show that interleukin-2 (IL-2) and IL-4 are elicited by the three confirmed candidates, but unexpectedly interferon-γ and tumor necrosis factor-α are not. We suggest that these pathogen components, discovered using genetic immunization and confirmed in a conventional protein format, will be useful toward the development of a safe and effective glanders vaccine.

Efficacy of Artemisia afra phytotherapy in experimental tuberculosis

Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in traditional practices. In this study we investigated whether extracts of A. afra are capable of controlling mycobacterial replication. For Mycobacterium aurum cultured in the presence of aqueous-, methanol- and dichloromethane (DCM) extracts of A. afra we found that bacterial replication was inhibited by the dichloromethane extract only. Activity of the DCM extract was confirmed in dose-dependent studies against both M. aurum and M. tuberculosis with an IC(50) =270 microg/ml and IC(50) = 290microg/ml, respectively. Fractionation of the DCM extract and evaluation of its efficacy in vitro found that most of the antimycobacterial activity was associated with isolate fraction C8 that contained several sesquiterpene lactones, the most prominent of which are Artemin and Arsubin. Evaluation of the bactericidal efficacy in vitro showed that isolate fraction C8 reduced replication of M. aurum and M. tuberculosis in a dose-dependent manner with IC(50) =1.9 microg/ml and IC(50) = 2.0 microg/ml, respectively, and an MIC = 10 microg/ml. Further, isolate fraction C8 and the DCM extract was administered to M. tuberculosis-infected mice at a tolerated dose of 1000 microg/kg for up to 26 weeks and mycobacterial burdens compared to untreated-, INH/RIF treated- and aqueous-extract-treated animals to assess its bactericidal activity in vivo. Bacterial replication remained unaffected during treatment with either isolate fraction C8 or the DCM extract resulting in pulmonary and splenic bacilli burdens comparable to that of untreated mice. In contrast, INH/RIF treatment cleared M. tuberculosis infection after only 8 weeks to undetectable levels. Interestingly, treatment of M. tuberculosis-infected mice with aqueous extract of A. afra regulated pulmonary inflammation during early infection notwithstanding its inability to inhibit mycobacterial growth. This study clearly demonstrates that A. afra contains in vitro anti-mycobacterial activity, modulates pulmonary inflammation in early mycobacterial infection, and that the mouse experimental tuberculosis model may serve as a useful assay for evaluating the utility of phytotherapy.

In vivo Bioluminescence Imaging of Burkholderia mallei Respiratory Infection and Treatment in the Mouse Model

Bioluminescent imaging (BLI) technology is a powerful tool for monitoring infectious disease progression and treatment approaches. BLI is particularly useful for tracking fastidious intracellular pathogens that might be difficult to recover from certain organs. Burkholderia mallei, the causative agent of glanders, is a facultative intracellular pathogen and has been classified by the CDC as a Category B select agent due to its highly infectious nature and potential use as a biological weapon. Very little is known regarding pathogenesis or treatment of glanders. We investigated the use of bioluminescent reporter constructs to monitor the dynamics of infection as well as the efficacy of therapeutics for B. mallei in real-time. A stable luminescent reporter B. mallei strain was created using the pUTmini-Tn5::luxKm2 plasmid and used to monitor glanders in the BALB/c murine model. Mice were infected via the intranasal route with 5 × 10³ bacteria and monitored by BLI at 24, 48, and 72 h. We verified that our reporter construct maintained similar virulence and growth kinetics compared to wild-type B. mallei and confirmed that it maintains luminescent stability in the presence or absence of antibiotic selection. The luminescent signal was initially seen in the lungs, and progressed to the liver and spleen over the course of infection. We demonstrated that antibiotic treatment 24 h post-infection resulted in reduction of bioluminescence that can be attributed to decreased bacterial burden in target organs. These findings suggest that BLI can be used to monitor disease progression and efficacy of therapeutics during glanders infections. Finally, we report an alternative method to mini-Tn5::luxKm2 transposon using mini-Tn7-lux elements that insert site-specifically at known genomic attachment sites and that can also be used to tag bacteria.

Alzheimers disease: review of emerging treatment role for intravenous immunoglobulins

Alzheimer’s disease (AD) is the most common neurodegenerative disorder. Currently available therapies are symptomatic but do not alter underlying disease progression. Immunotherapeutic approaches such as anti Aβ peptide active vaccination trials have had limited success to date. Intravenous immunoblobulin (IVIg) is widely used in immune-mediated neurological disorders such myasthenia gravis and Guillain-Barre syndrome. These preparations have been obtained from the pooled plasma of healthy human donors and contain natural anti-amyloid antibodies and are well tolerated. A small pilot study of passive immunotherapy using IVIg has suggested cognitive improvement. A multicenter phase III trial is ongoing and will determine whether or not this treatment can ameliorate cognitive deficits in mild-to-moderate AD. Here, we briefly review the pathogenic role of amyloid and tau in AD, as well as immunotherapeutic efforts to date. We also summarize what is known about naturally occurring anti-Aβ and tau antibodies in IVIg with a view toward explaining potential mechanisms underlying their therapeutic effects.

Development of reagents and assays for the detection of pathogenic Burkholderia species

Rapid detection of the category B biothreat agents Burkholderia pseudomallei and Burkholderia mallei in acute infections is critical to ensure that appropriate treatment is administered quickly to reduce an otherwise high probability of mortality (ca. 40% for B. pseudomallei). We are developing assays that can be used in clinical laboratories or security applications for the direct detection of surface-localized and secreted macromolecules produced by these organisms. We present our current medium-throughout approach for target selection and production of Burkholderia macromolecules and describe the generation of a Fab molecule targeted to the B. mallei BimA protein. We also present development of prototype assays for detecting Burkholderia species using anti-lipopolysaccharide antibodies.

Regulation of IgA responses in cattle, humans and mice

Secretory IgA (SIgA) constitutes the largest component of the humoral immune system of the body with gram quantities of this isotype produced by mammals on a daily basis. Secretory IgA (SIgA) antibodies function by both blocking pathogen/commensal entry at mucosal surfaces and virus neutralization. Several pathways of induction of IgA responses have been described which depend on T cells (T cell dependent or TD) pathways or are independent of T cells (T-independent or TI) and are mediated by dendritic cells (DCs) and/or epithelial cells. Many elements of IgA regulation readily cross species barriers (adjuvants, soluble and cognate factors) and are highly conserved whereas other pathways may be more specific to any given species and must be evaluated. Regulation of IgA production in cattle is not completely understood and thus we have focused in part on highly conserved factors such as transforming growth factor beta, Type I and Type 2 interferons, neuropeptides which interdigitate mucosal tissues (vasoactive intestinal peptide or VIP), and a small peptide (IgA inducing peptide or IGIP) which can serve as targets for modulation and increasing SIgA virus-specific antibodies. We have evaluated the potential utility of modulating these factors in vitro in regulation of qualitative aspects of antibodies of the IgM, IgG and IgA isotypes at mucosal surfaces and in secretions of the upper and lower respiratory tract to a virus of economic and public health importance, foot and mouth disease virus (FMDV). IgA responses in cattle are essential for host defense in response to various infectious agents. In cattle, IgA is not released into the colostrum, as is the case for other mammals but only IgG1 is selectively transported. In previous studies in cattle, IgA has been shown to be regulated by several cytokines including IFN-gamma, Type I interferons such as IFN-alpha and IFN-tau, transforming growth factor beta, IgA inducing peptide and other potential factors such as APRIL and BlyS which have not yet been fully evaluated in cattle. Many of these factors, namely TGF-beta and Type I interferons block cell cycle progression which is an essential component of Ig class switching and thus these factors require additional regulatory factors such as IL-2 to drive cells through cell cycle resulting in class switch recombination. Among these factors, IgA inducing peptide was originally identified from a bovine gut associated lymphoid tissue expression library and is highly conserved in pigs and humans at >90% at the amino acid level. The factor is regulated differently in various species but is consistently produced by dendritic cells.

Activation of porcine natural killer cells and lysis of foot-and-mouth disease virus infected cells

Natural killer (NK) cells play a vital role in innate response against viral infections and cellular transformation. In vivo modulation of their response may enhance their antiviral function. Here we describe the phenotype of porcine NK cells, test potential proinflammatory cytokines for activation of these cells and assess the capability of porcine NK cells to kill virus-infected or tumor cells in vitro. The CD2+/CD8+/CD3(-) cell compartment contained porcine NK cells, which at the resting stage were minimally cytotoxic toward foot-and-mouth disease virus (FMDV)-infected porcine cells or tumor cell lines. Direct stimulation of NK cells with proinflammatory cytokines induced efficient lysis of FMDV-infected cells with interleukin (IL)-2 or IL-15 showing the highest stimulatory capacity. Lower levels of NK cell activation were induced by IL-12, IL-18, or interferon (IFN)-alpha, however, IL-12 and IL-18 synergistically activated NK cells. Combinations of IL-15 and IL-12 or IL-15 and IL-18 did not further increase the porcine NK cell lytic capability over IL-15 alone. Natural killer cells expressed IFN-gamma regardless of the cytokine used for stimulation while expression of perforin increased modestly. The enhancement of porcine NK cell activity by proinflammatory cytokines offers a promising tool for development of antiviral approaches against virus infection.

Lipopolysaccharide from Burkholderia thailandensis E264 provides protection in a murine model of melioidosis

Burkholderia thailandensis is a less virulent close relative of Burkholderia pseudomallei, a CDC category B biothreat agent. We have previously shown that lipopolysaccharide (LPS) extracted from B. pseudomallei can provide protection against a lethal challenge of B. pseudomallei in a mouse model of melioidosis. Sugar analysis on LPS from B. thailandensis strain E264 confirmed that this polysaccharide has a similar structure to LPS from B. pseudomallei. Mice were immunised with LPS from B. thailandensis or B. pseudomallei and challenged with a lethal dose of B. pseudomallei strain K96243. Similar protection levels were observed when either LPS was used as the immunogen. This data suggests that B. thailandensis LPS has the potential to be used as part of a subunit based vaccine against pathogenic B. pseudomallei.

Present and future therapeutic strategies for melioidosis and glanders

Burkholderia pseudomallei and Burkholderia mallei are the causative agents of melioidosis and glanders, respectively. Both Gram-negative pathogens are endemic in many parts of the world. Although natural acquisition of these pathogens is rare in the majority of countries, these bacteria have recently gained much interest because of their potential as bioterrorism agents. In modern times, their potential destructive impact on public health has escalated owing to the ability of these pathogens to cause opportunistic infections in diabetic and perhaps otherwise immunocompromised people, two growing populations worldwide. For both pathogens, severe infection in humans carries a high mortality rate, both species are recalcitrant to antibiotic therapy - B. pseudomallei more so than B. mallei - and no licensed vaccine exists for either prophylactic or therapeutic use. The potential malicious use of these organisms has accelerated the investigation of new ways to prevent and to treat the diseases. The availability of several B. pseudomallei and B. mallei genome sequences has greatly facilitated target identification and development of new therapeutics. This review provides a compilation of literature covering studies in antimelioidosis and antiglanders antimicrobial drug discovery, with a particular focus on potential novel therapeutic approaches to combat these diseases.

Protective response to subunit vaccination against intranasal Burkholderia mallei and B. pseudomallei challenge

Burkholderia mallei and B. pseudomallei are Gram-negative pathogenic bacteria, responsible for the diseases glanders and melioidosis, respectively. Furthermore, there is currently no vaccine available against these Burkholderia species. In this study, we aimed to identify protective proteins against these pathogens. Immunization with recombinant B. mallei Hcp1 (type VI secreted/structural protein), BimA (autotransporter protein), BopA (type III secreted protein), and B. pseudomallei LolC (ABC transporter protein) generated significant protection against lethal inhaled B. mallei ATCC23344 and B. pseudomallei 1026b challenge. Immunization with BopA elicited the greatest protective activity, resulting in 100% and 60% survival against B. mallei and B. pseudomallei challenge, respectively. Moreover, sera from recovered mice demonstrated reactivity with the recombinant proteins. Dendritic cells stimulated with each of the different recombinant proteins showed distinct cytokine patterns. In addition, T cells from immunized mice produced IFN-γ following in vitro re-stimulation. These results indicated therefore that it was possible to elicit cross-protective immunity against both B. mallei and B. pseudomallei by vaccinating animals with one or more novel recombinant proteins identified in B. mallei.

Sero-characterization of lipopolysaccharide from Burkholderia thailandensis

We report the successful purification of lipopolysaccharide (LPS) from Burkholderia thailandensis, a Gram-negative bacterium, closely related to the highly pathogenic organisms B. pseudomallei and B. mallei. Burkholderia thailandensis LPS is shown to cross-react with rabbit and mouse sera obtained from inoculation with B. pseudomallei or B. mallei, respectively. These data suggest that B. thailandensis LPS shares similar structural features with LPS molecules from highly pathogenic Burkholderia species. This information may prove useful in ongoing efforts to develop novel vaccines and/or diagnostic reagents.

Burkholderia mallei cellular interactions in a respiratory cell model

Burkholderia mallei is a facultative intracellular pathogen that survives and replicates in phagocytic cell lines. The bacterial burden recovered from naïve BALB/c mice infected by intranasal delivery indicated that B. mallei persists in the lower respiratory system. To address whether B. mallei invades respiratory non-professional phagocytes, this study utilized A549 and LA-4 respiratory epithelial cells and demonstrated that B. mallei possesses the capacity to adhere poorly to, but not to invade, these cells. Furthermore, it was found that B. mallei was taken up by the murine alveolar macrophage cell line MH-S following serum coating, an attribute suggestive of complement- or Fc receptor-mediated uptake. Invasion/intracellular survival assays of B. mallei-infected MH-S cells demonstrated decreased intracellular survival, whilst a type III secretion system effector bopA mutant strain survived longer than the wild-type. Evaluation of the potential mechanism(s) responsible for efficient clearing of intracellular organisms demonstrated comparable levels of caspase-3 in both the wild-type and bopA mutant with characteristics consistent with apoptosis of infected MH-S cells. Furthermore, challenge of BALB/c mice with the bopA mutant by the intranasal route resulted in increased survival. Overall, these data suggest that B. mallei induces apoptotic cell death, whilst the BopA effector protein participates in intracellular survival.

Comparative antimicrobial activity of granulysin against bacterial biothreat agents

Granulysin is a cationic protein produced by human T cells and natural killer cells that can kill bacterial pathogens through disruption of microbial membrane integrity. Herein we demonstrate antimicrobial activity of the granulysin peptide derived from the active site against Bacillus anthracis, Yersinia pestis, Francisella tularensis, and Burkholderia mallei, and show pathogen-specific differences in granulysin peptide effects. The susceptibility of Y. pestis to granulysin is temperature dependent, being less susceptible when grown at the flea arthropod vector temperature (26°C) than when grown at human body temperature. These studies suggest that augmentation of granulysin expression by cytotoxic lymphocytes, or therapeutic application of granulysin peptides, could constitute important strategies for protection against select agent bacterial pathogens. Investigations of the microbial surface molecules that determine susceptibility to granulysin may identify important mechanisms that contribute to pathogenesis.

CD4+ T cells provide protection against acute lethal encephalitis caused by Venezuelan equine encephalitis virus

Studying the mechanisms of host survival resulting from viral encephalitis is critical to the development of vaccines. Here we have shown in several independent studies that high dose treatment with neutralizing antibody prior to intranasal infection with Venezuelan equine encephalitis virus had an antiviral effect in the visceral organs and prolonged survival time of infected mice, even in the absence of alphabeta T cells. Nevertheless, antibody treatment did not prevent the development of lethal encephalitis. On the contrary, the adoptive transfer of primed CD4(+) T cells was necessary to prevent lethal encephalitis in mice lacking alphabeta T cell receptor.

Synthesis and in vitro Efficacy Studies of Silver Carbene Complexes on Biosafety Level 3 Bacteria

A series of N-heterocyclic carbene silver complexes have been synthesized and tested against the select group of bio-safety level 3 bacteria Burkholderia pseudomallei, Burkholderia mallei, Bacillus anthracis, methicillin-resistant Staphylococcus aureus and Yersinia pestis. Minimal inhibitory concentrations, minimal bactericidal and killing assays demonstrated the exceptional efficacy of the complexes against these potentially weaponizable pathogens.

Evaluation of granulysin and perforin as candidate biomarkers for protection following vaccination with Mycobacterium bovis BCG or M. bovis delta-RD1 (81.10)

Development of improved vaccines against tuberculosis (TB) is directly correlated to the investigation of new and better correlates of protection after vaccination. We examined the kinetics of granulysin, perforin, IFN-gamma and Fas-L responses to M. bovis purified protein derivative (PPD) stimulation by peripheral blood mononuclear cells from BCG- and non-vaccinated cattle. Gene expression profiles following PPD stimulation showed significant increases in transcripts for granulysin and IFN-gamma in both CD4+ and CD8+ T cells in BCG-vaccinated as compared to non-vaccinated animals. Perforin & IFN-gamma examined by flow cytometry, showed a difference of 1-2% more PPD-specific cells in BCG-vaccinated than non-vaccinated animals. In a second trial, M. bovis BCG vaccinated animals had lower disease and pathological scores as compared to M. bovis Delta-RD1(a new vaccinate candidate) and the control group. Gene expression of granulysin and perforin were significantly increased in both vaccine groups (M. bovis BCG and M. bovis Delta-RD1 vaccinated) as compared to control after vaccination and challenge. IFN-gamma expression was increased only after vaccination and secretion was higher in the control, as compared to both vaccine groups demonstrating no correlation with protection upon vaccination.

Evaluation of granulysin and perforin as candidate biomarkers for protection following vaccination with Mycobacterium bovis BCG or M. bovisDeltaRD1

The development of improved vaccines against tuberculosis (TB) is directly linked to the investigation of new and better correlates of protection after vaccination against TB. Cloning and characterization of bovine homologues of the antimicrobial protein granulysin (Bo-lysin) and perforin by our group could be used as potential biomarkers for TB vaccination efficacy. In the present study, we examined the kinetics of granulysin, perforin, IFNgamma and Fas-L responses to Mycobacterium bovis purified protein derivative (PPD) stimulation by peripheral blood mononuclear cells from M. bovisDeltaRD1-, BCG- and non-vaccinated cattle. Gene expression profiles following PPD stimulation showed significant increases in transcripts for granulysin and IFNgamma in both CD4(+) and CD8(+) T cells in BCG-vaccinated as compared with non-vaccinated animals. Perforin and IFNgamma examined by flow cytometry, showed a difference of 1-2% more PPD-specific cells in BCG-vaccinated than non-vaccinated animals. In the vaccine trial, granulysin and perforin were significantly increased in both vaccine groups as compared with control after vaccination and challenge. IFNgamma expression was increased only after vaccination and secretion was higher in the control, non-protected group as compared with both vaccine groups demonstrating no correlation with protection upon vaccination. In summary, results shown here provide evidence that granulysin and perforin are prospective candidates as biomarkers of protection after vaccination against TB.

Human IgA-inducing protein from dendritic cells induces IgA production by naive IgD+ B cells

Over the last several years, there has been a great deal of progress in characterizing the role of dendritic cells (DCs) in the activation and modulation of B cells. DC-secreted chemokines can induce B cell trafficking to the lymph nodes. DC-produced survival factors such as B cell-activating factor of the TNF family and a proliferation-inducing ligand have been shown to be essential for B cell maturation, but have also been implicated in class-switch recombination and B cell lymphoma survival. Recently added to this list of DC-derived factors effecting B cells is IgA-inducing protein (IGIP). In this study, we characterize production of IGIP by human DCs, and examine its capacity to induce IgA class switching and differentiation of naive B cells in vitro. Monocyte-derived DCs were cultured in vitro with TLR agonists (TLR3, 4, 5, and 9) and other factors, including CD40 ligand, GM-CSF, and IL-4 as well as the neuropeptide vasoactive intestinal peptide. Under in vitro stimulation with vasoactive intestinal peptide and CD40L, IGIP mRNA expression could be up-regulated as much as 35-fold above nonstimulated samples within 12-48 h. Naive B cells cultured with exogenous recombinant human IGIP produced IgA in greater quantities than nonstimulated controls. Finally, we demonstrate that IGIP stimulation drives the production of mu-alpha switch circles from IgM(+)IgD(+) naive human B cells, indicating its role as an IgA switch factor.

Efficacy and immunogenicity of Mycobacterium bovis DeltaRD1 against aerosol M. bovis infection in neonatal calves

An attenuated Mycobacterium bovisRD1 deletion (DeltaRD1) mutant of the Ravenel strain was constructed, characterized, and sequenced. This M. bovis DeltaRD1 vaccine strain administered to calves at 2 weeks of age provided similar efficacy as M. bovis bacillus Calmette Guerin (BCG) against low dose, aerosol challenge with virulent M. bovis at 3.5 months of age. Approximately 4.5 months after challenge, both DeltaRD1- and BCG-vaccinates had reduced tuberculosis (TB)-associated pathology in lungs and lung-associated lymph nodes and M. bovis colonization of tracheobronchial lymph nodes as compared to non-vaccinates. Mean central memory responses elicited by either DeltaRD1 or BCG prior to challenge correlated with reduced pathology and bacterial colonization. Neither DeltaRD1 or BCG elicited IFN-gamma responses to rESAT-6:CFP-10 prior to challenge, an emerging tool for modern TB surveillance programs. The DeltaRD1 strain may prove useful for bovine TB vaccine programs, particularly if additional mutations are included to improve safety and immunogenicity.

Host immunity in the protective response to vaccination with heat-killed Burkholderia mallei

Background

We performed initial cell, cytokine and complement depletion studies to investigate the possible role of these effectors in response to vaccination with heat-killed Burkholderia mallei in a susceptible BALB/c mouse model of infection.

Results

While protection with heat-killed bacilli did not result in sterilizing immunity, limited protection was afforded against an otherwise lethal infection and provided insight into potential host protective mechanisms. Our results demonstrated that mice depleted of either B cells, TNF-α or IFN-γ exhibited decreased survival rates, indicating a role for these effectors in obtaining partial protection from a lethal challenge by the intraperitoneal route. Additionally, complement depletion had no effect on immunoglobulin production when compared to non-complement depleted controls infected intranasally.

Conclusion

The data provide a basis for future studies of protection via vaccination using either subunit or whole-organism vaccine preparations from lethal infection in the experimental BALB/c mouse model. The results of this study demonstrate participation of B220⁺ cells and pro-inflammatory cytokines IFN-γ and TNF-α in protection following HK vaccination.

Glanders: off to the races with Burkholderia mallei

Burkholderia mallei, the etiologic agent of the disease known as glanders, is primarily a disease affecting horses and is transmitted to humans by direct contact with infected animals. The use of B. mallei as a biological weapon has been reported and currently, there is no vaccine available for either humans or animals. Despite the history and highly infective nature of B. mallei, as well as its potential use as a bio-weapon, B. mallei research to understand the pathogenesis and the host responses to infection remains limited. Therefore, this minireview will focus on current efforts to elucidate B. mallei virulence, the associated host immune responses elicited during infection and discuss the feasibility of vaccine development.

Mycobacterium bovis BCG vaccination induces memory CD4+ T cells characterized by effector biomarker expression and anti-mycobacterial activity

The effector mechanisms used by CD4+ T cells to control mycobacteria differ between humans and rodent models of TB and should be investigated in additional animal models. In these studies, the bovine model was used to characterize the mycobactericidal CD4+ T cell response induced by vaccination with the attenuated Mycobacterium bovis bacillus Calmette-Guérin (BCG). Antigenic stimulation of peripheral blood CD4+ T cells from BCG-vaccinated cattle enhanced expression of perforin and IFNgamma in cells expressing a CD45RA-CD45RO+CD62L+ cell surface phenotype, enhanced transcription of granulysin, IFNgamma, perforin, IL-4, IL-13, and IL-21, and enhanced anti-mycobacterial activity of CD4+ T cells against BCG-infected macrophages.

Advances in immunology and vaccine discovery report of the United States-European Commission workshop

As the 21st century unfolds, infectious diseases remain one of the most significant threats to our economy, our food animal production systems, animal welfare, and most importantly, the lives of people worldwide, regardless of their economic standing. The potential use of biological threat agents for terrorism or biowarfare further undermines the security of our society. Arguably, vaccines represent the single most cost-effective, medically delivered strategy for confronting these challenges. The workshop "Advances in Immunology and Vaccine Discovery" was organized to address these challenges, based on the conviction that the interface between immunology and vaccinology offers the best prospects for major breakthroughs in vaccine discovery and development. Six focus areas were identified by workshop organizers: (1) pathogen immune evasion; (2) innate immunity; (3) mucosal immunity; (4) immunogenetics; (5) comparative immunology; and (6) genomics. These areas provided opportunities to elucidate how protective immunity may relate to the disruption of the molecular mechanisms that underlie host-pathogen interactions. A report generated by workshop organizers and participants provides key recommendations and identifies important research gaps, needs, future steps, and potential strategic US-EU collaborations. The report is available on line through ScienceDirect (URL).

Failure of a Mycobacterium tuberculosis DeltaRD1 DeltapanCD double deletion mutant in a neonatal calf aerosol M. bovis challenge model: comparisons to responses elicited by M. bovis bacille Calmette Guerin

An attenuated Mycobacterium tuberculosis RD1 knockout and pantothenate auxotroph (mc(2)6030) vaccine administered at 2 weeks of age failed to protect calves from low dose, aerosol M. bovis challenge at 2.5 months of age. In contrast, M. bovis bacille Calmette Guerin (BCG)-vaccinates had reduced tuberculosis-associated pathology as compared to non- and mc(2)6030-vaccinates. Mycobacterial colonization was not impacted by vaccination. Positive prognostic indicators associated with reduced pathology in the BCG-vaccinated group were decreased antigen induced IFN-gamma, iNOS, IL-4, and MIP1-alpha responses, increased antigen induced FoxP3 expression, and a diminished activation phenotype (i.e., downward arrow CD25+ and CD44+ cells and upward arrow CD62L+ cells) in mycobacterial-stimulated mononuclear cell cultures. The calf sensitization and challenge model provides an informative screen for candidate tuberculosis vaccines before their evaluation in costly non-human, primates.

Alpha-beta T cells provide protection against lethal encephalitis in the murine model of VEEV infection

We evaluated the safety and immunogenicity of a chimeric alphavirus vaccine candidate in mice with selective immunodeficiencies. This vaccine candidate was highly attenuated in mice with deficiencies in the B and T cell compartments, as well as in mice with deficient gamma-interferon responsiveness. However, the level of protection varied among the strains tested. Wild type mice were protected against lethal VEEV challenge. In contrast, alpha/beta (αβ) TCR-deficient mice developed lethal encephalitis following VEEV challenge, while mice deficient in gamma/delta (γδ) T cells were protected. Surprisingly, the vaccine potency was diminished by 50% in animals lacking interferon-gamma receptor alpha chain (R1)-chain and a minority of vaccinated immunoglobulin heavy chain-deficient (μMT) mice survived challenge, which suggests that neutralizing antibody may not be absolutely required for protection. Prolonged replication of encephalitic VEEV in the brain of pre-immunized mice is not lethal and adoptive transfer experiments indicate that CD3⁺ T cells are required for protection.

Early production of type I interferon during West Nile virus infection: role for lymphoid tissues in IRF3-independent interferon production

Infection of cells with flaviviruses in vitro is reduced by pretreatment with small amounts of type I interferon (IFN-alpha/beta). Similarly, pretreatment of animals with IFN and experiments using mice defective in IFN signaling have indicated a role for IFN in controlling flavivirus disease in vivo. These data, along with findings that flavivirus-infected cells block IFN signaling, suggest that flavivirus infection can trigger an IFN response. To investigate IFN gene induction by the very first cells infected during in vivo infection with the flavivirus West Nile virus (WNV), we infected mice with high-titer preparations of WNV virus-like particles (VLPs), which initiate viral genome replication in cells but fail to spread. These studies demonstrated a brisk production of IFN in vivo, with peak levels of over 1,000 units/ml detected in sera between 8 and 24 h after inoculation by either the intraperitoneal or footpad route. The IFN response was dependent on genome replication, and WNV genomes and WNV antigen-positive cells were readily detected in the popliteal lymph nodes (pLN) of VLP-inoculated mice. High levels of IFN mRNA transcripts and functional IFN were also produced in VLP-inoculated IFN regulatory factor 3 null (IRF3(-/-)) mice, indicating that IFN production was independent of the IRF3 pathways to IFN gene transcription, consistent with the IFN type produced (predominantly alpha).

An ESAT-6:CFP10 DNA vaccine administered in conjunction with Mycobacterium bovis BCG confers protection to cattle challenged with virulent M. bovis

The potency of genetic immunization observed in the mouse has demonstrated the utility of DNA vaccines to induce cell-mediated and humoral immune responses. However, it has been relatively difficult to generate comparable responses in non-rodent species. The use of molecular adjuvants may increase the magnitude of these suboptimal responses. In this study, we demonstrate that the co-administration of plasmid-encoded GM-CSF and CD80/CD86 with a novel ESAT-6:CFP10 DNA vaccine against bovine tuberculosis enhances antigen-specific cell-mediated immune responses. ESAT-6:CFP10+GM-CSF+CD80/CD86 DNA vaccinated animals exhibited significant (p<0.01) antigen-specific proliferative responses compared to other DNA vaccinates. Increased expression (p< or =0.05) of CD25 on PBMC from ESAT-6:CFP10+GM-CSF+CD80/CD86 DNA vaccinates was associated with increased proliferation, as compared to control DNA vaccinates. Significant (p<0.05) numbers of ESAT-6:CFP10-specific IFN-gamma producing cells were evident from all ESAT-6:CFP10 DNA vaccinated animals compared to control DNA vaccinates. However, the greatest increase in IFN-gamma producing cells was from animals vaccinated with ESAT-6:CFP10+GM-CSF+CD80/CD86 DNA. In a low-dose aerosol challenge trial, calves vaccinated as neonates with Mycobacterium bovis BCG and ESAT-6:CFP10+GM-CSF+CD80/CD86 DNA exhibited decreased lesion severity in the lung and lung-associated lymph nodes following viruluent M. bovis challenge compared to other vaccinated animals or non-vaccinated controls. These data suggest that a combined vaccine regimen of M. bovis BCG and a candidate ESAT-6:CFP10 DNA vaccine may offer greater protection against tuberculosis in cattle than vaccination with BCG alone.

Natural Killer cell function during foot-and-mouth disease virus infection (46.19)

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. Immunological knowledge to assess more rapid acting vaccines against FMDV is presently limited. We examined the reactivity of swine and cattle NK cells following infection for their capability to express intracellular perforin, to kill a human tumor cell line target in vitro, and to secret IFN gamma. The cytotoxicity of NK cells from non-infected animals against the K562 cells is low with baseline levels at 5–15% in swine and 15–20% in cattle. Stimulation with rhIL-2 or rhIL-12 plus rhIL-15, increased the lytic activity against K562 cells. Infection with FMDV inhibited swine NK cell lytic activity but did not significantly increase IFN gamma secretion during the acute infection. Perforin expression increased but this did not correlate with the killing capability of the swine NK cells. Infection of cattle with FMDV initially activated the NK cells to increase target cell lysis. NK cell IFN gamma secretion and perforin expression were slightly elevated upon infection and coincided with the lytic activity in cattle. These results are a further indication of immune evasion by FMDV by inhibiting or limiting NK cell function. The potential to manipulate the innate immune response to block this evasion is discussed in the context of designing rapid acting vaccines for foot-and-mouth disease.

Biomarkers of CD4+ CTL cell mediated immunity to tuberculosis (43.51)

The immune responses mediated by interactions between T-lymphocyte subsets and mycobacteria-infected macrophages are critical for control of tuberculosis . In these studies, the bovine model was used to characterize the cytolytic and mycobactericidal CD4+ T cell response induced by BCG vaccination. Antigenic stimulation of CD4+ T-cells from BCG vaccinated cattle induced expression of perforin and IFNgamma in cells expressing a CD45RA−, CD45RO+, and CD62L+ cell surface phenotype. Antigen specific enhancement of granulysin, IFNgamma, perforin, IL-4, IL-13, and IL-21 mRNA expression was detected and not detected for IL-2, IL-6, IL-10, IL-15, TNFα, FasL, and CD40L. Following antigenic stimulation, CD4+ T cells from BCG vaccinated animals contributed to reduction of intracellular BCG in infected macrophages. These results demonstrate that vaccination with BCG induces a subpopulation of mycobacteria-specific CD4+ T cells that are characterized by the expression of a cell-surface memory phenotype, enhanced expression of mycobactericidal molecules, and anti-mycobacterial activity against intracellular M. bovis.

This work was supported by the NIAID Fellowship for Training in Emerging and Re-emerging Infectious Disease and the Sealy Center for Vaccine Development, UTMB, the Texas-United Kingdom Collaborative Research Initiative, and the Institute for Animal Health by DEFRA and the BBSRC, UK.

Role of effector B and T lymphocytes and cytokine production in the protective host response to vaccination with heat killed bacilli against Burkholderia mallei (43.14)

Burkholderia mallei, the etiologic agent of glanders disease, is a gram-negative, intracellular bacterium for which no vaccine is available. Consequently, we are interested in defining protective host immune responses to B. mallei infection with the goal of developing candidate vaccines. Here, we report on initial cell/cytokine depletion studies to investigate the possible role these effectors may play in response to vaccination with heat killed bacilli in a susceptible BALB/c mouse model of infection. While protection with heat killed bacilli does not result in sterilizing immunity, protection is afforded against an otherwise lethal infection and provides insight into potential host protective mechanisms. Our results demonstrate that mice treated with either anti-B220, TNF-α or IFN-γ monoclonal antibodies exhibited decreased survival rates, indicating a key role for vaccine induced antibody and early cytokine production in protection from lethal challenge infection by the intraperitoneal route.

Vesicular stomatitis New Jersey virus (VSNJV) infects keratinocytes and is restricted to lesion sites and local lymph nodes in the bovine, a natural host

Inoculation of vesicular stomatitis New Jersey virus (VSNJV) by skin scarification of the coronary-band in cattle, a natural host of VSNJV, resulted in vesicular lesions and 6-8 log(10) TCID(50) increase in skin virus titers over a 72 h period. Virus infection was restricted to the lesion sites and lymph nodes draining those areas but no virus or viral RNA was found in the blood or in 20 other organs and tissues sampled at necropsy. Scarification of flank skin did not result in lesions or a significant increase in viral titer indicating that viral clinical infection is restricted to skin inoculation at sites where lesions naturally occur. Viral antigens co-localized primarily with keratinocytes in the coronary band, suggesting these cells are the primary site of viral replication. Viral antigen also co-localized with few MHC-II positive cells, but no co-localization was observed in cells positive for macrophage markers. Although granulocyte infiltration was observed in lesions, little viral antigen co-localized with these cells. This is the first detailed description of VSNJV tissue distribution and infected cell characterization in a natural host. The pathogenesis model shown herein could be useful for in-vivo tracking of virus infection and local immune responses.

Estrogen increases menopausal host susceptibility to experimental ascending urinary-tract infection

The protective effect of estrogen replacement on ascending urinary-tract infection (UTI) is controversial. We designed a study using an experimental model of UTI in which surgically menopausal mice were supplemented with estrogen and the susceptibility to UTI was evaluated after experimental Escherichia coli infection. The mean rate of E. coli infection in the group not treated with estrogen was 2 x 10(4) cfu/g of renal tissue, compared with 9 x 10(8) cfu/g (P<.001) in the estrogen-treated group. Surprisingly, despite the hypothesis that estrogen would protect mice from infection, estrogen treatment significantly increased the susceptibility of the mice to ascending UTI.

Environmental estrogens induce mast cell degranulation and enhance IgE-mediated release of allergic mediators

BACKGROUND

Prevalence and morbidity of allergic diseases have increased over the last decades. Based on the recently recognized differences in asthma prevalence between the sexes, we have examined the effect of endogenous estrogens on a key element of the allergic response. Some lipophilic pollutants have estrogen-like activities and are termed environmental estrogens. These pollutants tend to degrade slowly in the environment and to bioaccumulate and bioconcentrate in the food chain; they also have long biological half-lives.

OBJECTIVES

Our goal in this study was to identify possible pathogenic roles for environmental estrogens in the development of allergic diseases.

METHODS

We screened a number of environmental estrogens for their ability to modulate the release of allergic mediators from mast cells. We incubated a human mast cell line and primary mast cell cultures derived from bone marrow of wild type and estrogen receptor alpha (ER-alpha)-deficient mice with environmental estrogens with and without estradiol or IgE and allergens. We assessed degranulation of mast cells by quantifying the release of beta-hexosaminidase.

RESULTS

All of the environmental estrogens tested caused rapid, dose-related release of beta-hexosaminidase from mast cells and enhanced IgE-mediated release. The combination of physiologic concentrations of 17beta-estradiol and several concentrations of environmental estrogens had additive effects on mast cell degranulation. Comparison of bone marrow mast cells from ER-alpha-sufficient and ER-alpha-deficient mice indicated that much of the effect of environmental estrogens was mediated by ER-alpha.

CONCLUSIONS

Our findings suggest that estrogenic environmental pollutants might promote allergic diseases by inducing and enhancing mast cell degranulation by physiologic estrogens and exposure to allergens.

Estradiol activates mast cells via a non-genomic estrogen receptor-alpha and calcium influx

BACKGROUND

Allergic airway diseases are more common in females than in males during early adulthood. A relationship between female hormones and asthma prevalence and severity has been suggested, but the cellular and molecular mechanisms are not understood.

OBJECTIVE

To elucidate the mechanism(s) by which estrogens enhance the synthesis and release of mediators of acute hypersensitivity.

METHODS

Two mast cell/basophil cell lines (RBL-2H3 and HMC-1) and primary cultures of bone marrow derived mast cells, all of which naturally express estrogen receptor-alpha, were examined. Cells were incubated with physiological concentrations of 17-beta-estradiol with and without IgE and allergens. Intracellular Ca(2+) concentrations and the release of beta-hexosaminidase and leukotriene C(4) were quantified.

RESULTS

Estradiol alone induced partial release of the preformed, granular protein beta-hexosaminidase from RBL-2H3, BMMC and HMC-1, but not from BMMC derived from estrogen receptor-alpha knock-out mice. The newly synthesized LTC(4) was also released from RBL-2H3. Estradiol also enhanced IgE-induced degranulation and potentiated LTC(4) production. Intracellular Ca(2+) concentration increased prior to and in parallel with mediator release. Estrogen receptor antagonists or Ca(2+) chelation inhibited these estrogenic effects.

CONCLUSION

Binding of physiological concentrations of estradiol to a membrane estrogen receptor-alpha initiates a rapid onset and progressive influx of extracellular Ca(2+), which supports the synthesis and release of allergic mediators. Estradiol also enhances IgE-dependent mast cell activation, resulting in a shift of the allergen dose response.

Potential of ancestral sylvatic dengue-2 viruses to re-emerge

Dengue viruses (DENV) are the most important arboviral pathogens in tropical and subtropical regions throughout the world. DENV transmission includes both a sylvatic, enzootic cycle between nonhuman primates and arboreal mosquitoes of the genus Aedes, and an urban, endemic/epidemic cycle between Aedes aegypti, a mosquito with larval development in peridomestic water containers, and human reservoir hosts. All 4 serotypes of endemic DENV evolved independently from ancestral sylvatic viruses and have become both ecologically and evolutionarily distinct; this process may have involved adaptation to (i) peridomestic mosquito vectors and/or (ii) human reservoir hosts. To test the latter hypothesis, we assessed the ability of sylvatic and endemic DENV-2 strains, representing major genotypes from Southeast Asia, West Africa and the Americas, to replicate in two surrogate human model hosts: monocyte-derived, human dendritic cells (moDCs), and mice engrafted with human hepatoma cells. Although the various DENV-2 strains showed significant inter-strain variation in mean replication titers in both models, no overall difference between sylvatic and endemic strains was detected in either model. Our findings suggest that emergence of endemic DENV strains from ancestral sylvatic strains may not have required adaptation to replicate more efficiently in human reservoir hosts, implying that the potential for re-emergence of sylvatic dengue strains into the endemic cycle is high. The shared replication profiles of the American endemic and sylvatic strains suggest that American strains have maintained or regained the ancestral phenotype.

Estrogenic regulation of host immunity against an estrogen receptor-negative human breast cancer

PURPOSE

The risk of developing breast cancer is positively correlated with exposure to increased levels of estrogen and/or an increased duration of estrogen exposure. Many different mechanisms have been proposed to explain the association of estrogens with breast cancer risk; however, the well-documented immune modulatory properties of estrogen have received little attention. In part, this is due to a lack of suitable models for studying this relationship.

EXPERIMENTAL DESIGN

We have developed an animal model using estrogen receptor (ER)-negative human breast cancer cell line, MDA-MB-468, xenografted into severe combined immunodeficient (SCID) mice. We also generated the ER-alpha knockout (ER-alphaKO) mice on the SCID background and then tested the ability of 17beta-estradiol to stimulate growth of xenografted ER-negative human breast cancer tumors in wild-type and ER-alphaKO SCID mice. We quantified vascularization of tumors, macrophage recruitment to the tumor site by immunocytochemistry, and inflammatory cytokine production.

RESULTS

We show that estrogen treatment of C57BL/6/SCID mice promotes the growth of xenografted ER-negative tumors in wild-type mice and this estrogen-induced tumor growth is abrogated in ER-alphaKO mice. Tumor neovascularization of estrogen-treated mice was unchanged versus control; however, estrogen treatment of the C57BL/6/SCID host suppressed macrophage recruitment to and inflammatory cytokine production at the tumor site.

CONCLUSIONS

These data are consistent with estrogen modulation of the inflammatory response as a contributing factor in estrogen-stimulated growth of an ER-negative tumor. This effect on the host innate immune response was mediated by ER-alpha.

Lung Lesions in SCID-bo and SCID-bg Mice after Intratracheal Inoculation with Wild-type or Leucotoxin-deficient Mutant Strains of Mannheimia haemolytica Serotype 1

The purpose of this study was to investigate SCID-bg mice engrafted with bovine haematolymphoid tissues (SCID-bo) as a model for studying bovine Mannheimia haemolytica serotype 1- induced pneumonia, in which leucotoxin (LKT) plays a major role. In experiment A, SCID-bo and SCID-bg mice were inoculated intratracheally with either (1) phosphate-buffered saline (PBS), (2) M. haemolytica wild-type strain 89010807N ("LKT(+)WT"), (3) a M. haemolytica leucotoxin-deficient mutant of strain 89010807N ("LKT(-)mutant"), or (4) the M. haemolytica wild-type Oklahoma strain. Mice were killed for examination at intervals between 20 and 44h after inoculation. Lung lesions consisted of thickened alveolar septa and neutrophil and macrophage infiltrates in the bronchioles and alveoli. Lung lesion scores in the SCID-bo mice inoculated with LKT(+)WT or LKT(-) mutant were significantly (P<0.05) greater than those of the PBS control group, but the two bacterial strains produced results that did not differ significantly. M. haemolytica was isolated from lung, liver and spleen after inoculation but less frequently as time progressed. In experiment B, SCID-bg mice were inoculated intratracheally with live LKT(+)WT or formalin-killed LKT(+)WT and killed 24, 48 or 96 h later. Lung lesions were histologically similar to those observed in experiment A; however, there were no significant differences in the lung lesion scores between groups. It was concluded that the lesions seen in this study were probably not due to LKT, and that the SCID-bo mouse does not provide a good rodent model for bovine pneumonia.

Estrogen receptor alpha (ERalpha) deficiency in macrophages results in increased stimulation of CD4+ T cells while 17beta-estradiol acts through ERalpha to increase IL-4 and GATA-3 expression in CD4+ T cells independent of antigen presentation

The effects of 17beta-estradiol (E2) on immune function have been extensively reported. The effects are dependent on concentration and duration of exposure and potential differences in signaling between the known E2 receptors, estrogen receptors (ER) alpha and ERbeta. Through the use of ER-deficient mice, we and others have begun to demonstrate the role of the two known receptors in modulating immune functional activities. Previous studies have shown that cells of the innate immune system have altered function (bactericidal capacity) and patterns of cytokine expression (increased proinflammatory cytokine expression) through amelioration of ERalpha signaling. In this study, we extend these studies to analysis of T cell differentiation and proliferation in APC-dependent and APC-independent in vitro assay systems. Our results demonstrate that ERalpha deficiency in splenic macrophages, but not CD11c+ splenic dendritic cells pulsed with OVA significantly enhances proliferative responses and IFN-gamma production by transgenic OVA peptide-specific (OT-II) CD4+ T cells when compared with Ag-pulsed APC from wild-type littermates. The addition of E2 in this culture system did not significantly affect the production of IFN-gamma. In addition, when purified CD4+ T cells from ERalpha-deficient and wild-type littermates were stimulated with anti-CD3/CD28 Ab in the absence of E2, there were no significant differences in IFN-gamma or IL-4 production. However, the addition of E2 significantly increased IL-4 secretion, as well as increased GATA-3 mRNA levels from ERalpha-replete CD4+ T cells, while this effect was abrogated in ERalpha-deficient CD4+ T cells.