Ebola Virus Disease Features Hemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome in the Rhesus Macaque Model

BACKGROUND

Ebola virus (EBOV) disease (EVD) is one of the most severe and fatal viral hemorrhagic fevers and appears to mimic many clinical and laboratory manifestations of hemophagocytic lymphohistiocytosis syndrome (HLS), also known as macrophage activation syndrome. However, a clear association is yet to be firmly established for effective host-targeted, immunomodulatory therapeutic approaches to improve outcomes in patients with severe EVD.

METHODS

Twenty-four rhesus monkeys were exposed intramuscularly to the EBOV Kikwit isolate and euthanized at prescheduled time points or when they reached the end-stage disease criteria. Three additional monkeys were mock-exposed and used as uninfected controls.

RESULTS

EBOV-exposed monkeys presented with clinicopathologic features of HLS, including fever, multiple organomegaly, pancytopenia, hemophagocytosis, hyperfibrinogenemia with disseminated intravascular coagulation, hypertriglyceridemia, hypercytokinemia, increased concentrations of soluble CD163 and CD25 in serum, and the loss of activated natural killer cells.

CONCLUSIONS

Our data suggest that EVD in the rhesus macaque model mimics pathophysiologic features of HLS/macrophage activation syndrome. Hence, regulating inflammation and immune function might provide an effective treatment for controlling the pathogenesis of acute EVD.

Bacterial-Derived Outer Membrane Vesicles are Potent Adjuvants that Drive Humoral and Cellular Immune Responses

Discovery and development of novel adjuvants that can improve existing or next generation vaccine platforms have received considerable interest in recent years. In particular, adjuvants that can elicit both humoral and cellular immune responses would be particularly advantageous because the majority of licensed vaccines are formulated with aluminum hydroxide (alum) which predominantly promotes antibodies. We previously demonstrated that bacterial-derived outer membrane vesicles (OMV) possess inherent adjuvanticity and drive antigen-specific antibody and cellular immune responses to OMV components. Here, we investigated the ability of OMVs to stimulate innate and adaptive immunity and to function as a stand-alone adjuvant. We show that OMVs are more potent than heat-inactivated and live-attenuated bacteria in driving dendritic cell activation in vitro and in vivo. Mice immunized with OMVs admixed with heterologous peptides generated peptide-specific CD4 and CD8 T cells responses. Notably, OMV adjuvant induced much greater antibody and B cell responses to co-delivered ovalbumin compared to the responses elicited by the adjuvants alum and CpG DNA. Additionally, pre-existing antibodies raised against the OMVs did not impair OMV adjuvanticity upon repeat immunization. These results indicate that vaccines adjuvanted with OMVs elicit robust cellular and humoral immune responses, supporting further development of OMV adjuvant for use in next-generation vaccines.

A Lassa Virus Live-Attenuated Vaccine Candidate Based on Rearrangement of the Intergenic Region

Lassa virus (LASV) poses a significant public health problem within the regions of Lassa fever endemicity in Western Africa. LASV infects several hundred thousand individuals yearly, and a considerable number of Lassa fever cases are associated with high morbidity and lethality. No approved LASV vaccine is available, and current therapy is limited to an off-label usage of ribavirin that is only partially effective and associated with significant side effects. The impact of Lassa fever on human health, together with the limited existing countermeasures, highlights the importance of developing effective vaccines against LASV. Here, we present the development and characterization of a recombinant LASV (rLASV) vaccine candidate [rLASV(IGR/S-S)], which is based on the presence of the noncoding intergenic region (IGR) of the small (S) genome segment (S-IGR) in both large (L) and S LASV segments. In cultured cells, rLASV(IGR/S-S) was modestly less fit than wild-type rLASV (rLASV-WT). rLASV(IGR/S-S) was highly attenuated in guinea pigs, and a single subcutaneous low dose of the virus completely protected against otherwise lethal infection with LASV-WT. Moreover, rLASV(IGR/S-S) was genetically stable during serial passages in cultured cells. These findings indicate that rLASV(IGR/S-S) can be developed into a LASV live-attenuated vaccine (LAV) that has the same antigenic composition as LASV-WT and a well-defined mechanism of attenuation that overcomes concerns about increased virulence that could be caused by genetic changes in the LAV during multiple rounds of multiplication.IMPORTANCE Lassa virus (LASV), the causative agent of Lassa fever, infects several hundred thousand people in Western Africa, resulting in many lethal Lassa fever cases. No U.S. Food and Drug Administration-licensed countermeasures are available to prevent or treat LASV infection. We describe the generation of a novel LASV live-attenuated vaccine candidate rLASV(IGR/S-S), which is based on the replacement of the large genomic segment noncoding intergenic region (IGR) with that of the small genome segment. rLASV(IGR/S-S) is less fit in cell culture than wild-type virus and does not cause clinical signs in inoculated guinea pigs. Importantly, rLASV(IGR/S-S) protects immunized guinea pigs against an otherwise lethal exposure to LASV.

A Lassa Fever Live-Attenuated Vaccine Based on Codon Deoptimization of the Viral Glycoprotein Gene

Lassa virus (LASV) is endemic in Western Africa and is estimated to infect hundreds of thousands of individuals annually. A considerable number of these infections result in Lassa fever (LF), which is associated with significant morbidity and a case-fatality rate as high as 69% among hospitalized confirmed patients. U.S. Food and Drug Administration-approved LF vaccines are not available. Current antiviral treatment is limited to off-label use of a nucleoside analogue, ribavirin, that is only partially effective and associated with significant side effects. We generated and characterized a recombinant LASV expressing a codon-deoptimized (CD) glycoprotein precursor gene (GPC), rLASV-GPC/CD. Comparison of growth kinetics and peak titers showed that rLASV-GPC/CD is slightly attenuated in cell culture compared to wild-type (WT) recombinant LASV (rLASV-WT). However, rLASV-GPC/CD is highly attenuated in strain 13 and Hartley guinea pigs, as reflected by the absence of detectable clinical signs in animals inoculated with rLASV-GPC/CD. Importantly, a single subcutaneous dose of rLASV-GPC/CD provides complete protection against an otherwise lethal exposure to LASV. Our results demonstrate the feasibility of implementing a CD approach for developing a safe and effective LASV live-attenuated vaccine candidate. Moreover, rLASV-GPC/CD might provide investigators with a tool to safely study LASV outside maximum (biosafety level 4) containment, which could accelerate the elucidation of basic aspects of the molecular and cell biology of LASV and the development of novel LASV medical countermeasures.IMPORTANCE Lassa virus (LASV) infects several hundred thousand people in Western Africa, resulting in many lethal Lassa fever (LF) cases. Licensed LF vaccines are not available, and anti-LF therapy is limited to off-label use of the nucleoside analog ribavirin with uncertain efficacy. We describe the generation of a novel live-attenuated LASV vaccine candidate. This vaccine candidate is based on mutating wild-type (WT) LASV in a key region of the viral genome, the glycoprotein precursor (GPC) gene. These mutations do not change the encoded GPC but interfere with its production in host cells. This mutated LASV (rLASV-GPC/CD) behaves like WT LASV (rLASV-WT) in cell culture, but in contrast to rLASV-WT, does not cause disease in inoculated guinea pigs. Guinea pigs immunized with rLASV-GPC/CD were protected against an otherwise lethal exposure to WT LASV. Our results support the testing of this candidate vaccine in nonhuman primate models ofLF.

Determining the contribution of antigen-specific, CD4+ recent thymic emigrants to Salmonella persistence in vivo (LYM5P.661)

Typhoid fever, caused by infection with Salmonella bacteria affects approximately 21 million people annually, killing nearly 200,000. Recent thymic emigrants (RTEs) are the youngest subset of peripheral T cells, which are known to differ in how they functionally contribute to the naïve T cell pool. This distinctive cell population is known to contribute to the maintenance of T cell receptor diversity in the peripheral T cell pool, but their involvement in combating chronic bacterial infections, such as typhoid fever, has not been explored. In the present study, we hypothesized that RTEs are essential contributors to the CD4 T cell response during persistent Salmonella Typhimurium (ST) infection, which predominantly relies on helper T cell immunity to control bacteria. Here, we show that thymectomy of adult mice prior to oral infection with ST led to significantly increased bacterial burdens in the spleen, mesenteric lymph nodes and liver 30 days post-infection compared to sham surgical controls, suggesting Salmonella-specific RTEs may contribute to bacterial clearance. Surprisingly, existing peripheral Salmonella-specific T cells also increased significantly in number, implying that these cells are somehow incapable of controlling infection in the absence of RTEs. The results of this study provide insight into how new pathogen-specific T cells leaving the thymus participate in combatting a persistent bacterial infection.

Amelioration of lesions associated with 24-hour suboptimal platelet storage at 16 °C by a p38MAPK inhibitor, VX-702

BACKGROUND AND OBJECTIVES

Previous studies with p38MAPK inhibitors at room temperature demonstrated that they improve a large number of platelet storage parameters, but cannot substantially inhibit p38MAPK activation nor protect against widespread decrements in platelet quality parameters during 4 °C storage. In this study, platelet quality parameters and inhibition of p38MAPK by VX-702 were studied after incubation of platelets at 16 °C without agitation, suboptimal storage conditions which produce moderate platelet decrements.

MATERIALS AND METHODS

Trima apheresis units were collected and aliquoted into three 60-ml CLX storage bags: (i) a control aliquot which was held at 20-24 °C with constant agitation; (ii) a test aliquot which was held at 20-24 °C with agitation until Day 2, when it was reincubated at 16 ± 1 °C for 24 ± 0·5 h without agitation and then returned 20-24 °C with agitation; (iii) a test aliquot containing 1 μm VX-702 stored in an identical fashion as aliquot 2. Aliquots were tested for an array of platelet storage parameters and p38MAPK activation on Days 1, 4 and 7.

RESULTS

Many platelet storage parameters and p38MAPK activation were adversely affected by 24-h incubation at 16 °C without agitation. With the exception of ESC, addition of VX-702 prevented p38MAPK activation and the decrements in most observed parameters.

CONCLUSION

Unlike 4 °C storage, VX-702 prevents activation of p38MAPK and decrements in many platelet storage parameters after exposure to 16 °C without agitation for 24 h.

Liver induced immunosuppression by Salmonella-specific CD4 T cells during persistent infection (P3097)

What role microenvironments play in dictating immune outcomes during infection is largely unknown. Our lab uniquely combines a murine model of persistent S. typhimurium infection with recombineered Salmonella strains and MHC-II tetramers to visualize endogenous Salmonella-specific CD4 T cell responses during infection in various organs. We hypothesize that an immunological stalemate between bacterial persistence and the host immune response is determined by anatomical location, which dictates T cell function and infection outcome. We show Salmonella-specific CD4 T cells adoptively transferred from lymphoid organs protect mice from subsequent challenge, while CD4 T cells transferred from infected livers increase susceptibility. Furthermore, lymphoid Salmonella-specific Th1-cells produce higher levels of interferon-γ, while FoxP3- liver CD4 T cells produce larger amounts of interleukin-10, with a decreased proliferative capacity. Additionally, we show lymphoid Th1 cells are potent activators of iNOS and reduce macrophage bacterial loads, while liver-derived Tr1-like cells fail to control bacterial replication, through attenuated iNOS activation. Whether these immunosuppressive Tr1-like cells are induced in the liver, or phenotypically switch upon entering the organ, remains under investigation. These results demonstrate that during persistent Salmonella infection different immunological responses occur at different anatomical sites, which may dictate the outcome of infection.

A naturally derived outer-membrane vesicle vaccine protects against lethal pulmonary Burkholderia pseudomallei infection

Burkholderia pseudomallei, and other members of the Burkholderia, are among the most antibiotic-resistant bacterial species encountered in human infection. Mortality rates associated with severe B. pseudomallei infection approach 50% despite therapeutic treatment. A protective vaccine against B. pseudomallei would dramatically reduce morbidity and mortality in endemic areas and provide a safeguard for the U.S. and other countries against biological attack with this organism. In this study, we investigated the immunogenicity and protective efficacy of B. pseudomallei-derived outer membrane vesicles (OMVs). Vesicles are produced by Gram-negative and Gram-positive bacteria and contain many of the bacterial products recognized by the host immune system during infection. We demonstrate that subcutaneous (SC) immunization with OMVs provides significant protection against an otherwise lethal B. pseudomallei aerosol challenge in BALB/c mice. Mice immunized with B. pseudomallei OMVs displayed OMV-specific serum antibody and T-cell memory responses. Furthermore, OMV-mediated immunity appears species-specific as cross-reactive antibody and T cells were not generated in mice immunized with Escherichia coli-derived OMVs. These results provide the first compelling evidence that OMVs represent a non-living vaccine formulation that is able to produce protective humoral and cellular immunity against an aerosolized intracellular bacterium. This vaccine platform constitutes a safe and inexpensive immunization strategy against B. pseudomallei that can be exploited for other intracellular respiratory pathogens, including other Burkholderia and bacteria capable of establishing persistent infection.

Phase II trial of pegylated liposomal doxorubicin-cyclophosphamide combination as first-line chemotherapy in elderly metastatic breast cancer patients

19565

Background: Although the majority of metastatic breast cancer (MBC) patients (pts) responds to endocrine therapy, treatment failure is a concern, as well as front-line therapy for pts with ER/PR negative disease.The combination of anthracyclines (A) and cyclophosphamide (C) is active in younger pts, but cardiac toxicity of A in elderly MBC pts has to be considered. Pegylated liposomal doxorubicin (PLD) (Caelyx®) is active in MBC and has much less cardiotoxicity than A, and we present the preliminary data of the PLD/C in elderly MBC pts. Methods: This was a multicentric phase II trial. Inclusion criteria included: pts aged between 65 and 75, histologically proven measurable MBC, ECOG PS 0–1, LVEF = 50%, first-line chemotherapy for MBC. Prior adjuvant chemotherapy was allowed if stopped for = 6 or 12 months without and with anthracyclines, respectively. Endocrine therapy either in the adjuvant or metastatic setting had to be stopped for = 1 month. All pts gave a written informed consent. The treatment schedule was : PLD 40mg/m2 and C 500mg/m2 d1 every 4 weeks. Efficacy as well as response duration and tolerance were the primary and secondary end-points, respectively. Results: 35 patients were enrolled (Median age 71.3, range 65.6–75.9). A total of 166 cycles have been administered. The median number of cycles was 6 (range 1–9). No toxic death was reported, one patient died of diabetes mellitus decompensation. No congestive heart failure or decrease in LVEF was reported, although 1 pt experience grade 3 dyspnea and stopped treatment. Other (gr3–4) NCI-CTC toxicity included: neutropenia in 7 (gr3) and 3 (gr4) pts; gr3 mucositis (4). No febrile neutropenia was reported. Grade 3 hand-foot syndrome occurred in 1 pt, whereas treatment was stopped due to a generalized rash in 1 pt. An objective response (CR + PR) was achieved in 10 (28,6%) pts (1 CR and 8 PR), and a disease control in 24 (68.6%) with a progression free survival of 8.8 months and a median survival of 20.4 months Conclusions: The LPD-C combination is active in elderly MBC pts, with an acceptable toxicity profile.

No significant financial relationships to disclose.

Resistance against heterogeneous sequential infections: experimental studies with a tapeworm and its copepod host

Parasite heterogeneity is thought to be an important factor influencing the likelihood and the dynamics of infection. Previous studies have demonstrated that simultaneous exposure of hosts to a heterogeneous mixture of parasites might increase infection success. Here this view is extended towards the effect of parasite heterogeneity on subsequent infections. Using a system of the tapeworm Schistocephalus solidus and its copepod intermediate host, heterogeneity of the tapeworm surface carbohydrates is investigated, i.e. structures that are potentially recognized by the invertebrate host's immune system. With lectin labelling, a significant proportion of variation in surface carbohydrates is related to differences in worm sibships (i.e. families). Tapeworm sibships were used for experimental exposure of copepods to either homogeneous combinations of tapeworm larvae, i.e. worms derived from the same sibship or heterogeneous mixtures of larvae, and copepods were subsequently challenged with an unrelated larva to study re-infection. Contrary to expectation, neither an effect of parasite heterogeneity on the current infection, nor on re-infection were found. The effect of parasitic heterogeneity on host immunity is therefore complex, potentially involving increased cross-protection on the one hand, with higher costs of raising a more heterogeneous immune response on the other.

Infectivity of two nematode parasites, Camallanus lacustris and Anguillicola crassus, in a paratenic host, the three-spined stickleback Gasterosteus aculeatus

Three-spined sticklebacks Gasterosteus aculeatus are frequent paratenic hosts of the nematode parasites Anguillicola crassus and Camallanus lacustris. As paratenic hosts, sticklebacks could spread infection by carrying high numbers of infective stages. In contrast, low infective ability of either parasite for the paratenic host could hinder the spread of infection. In the present study, G. aculeatus was, for the first time, infected under controlled laboratory conditions with defined doses of the parasites. Sticklebacks were exposed to 6, 12, 18 and 24 parasite larvae to determine the infective ability of the 2 nematode species. There were significantly higher infection rates for C. lacustris (18 to 49%) than for A. crassus (4 to 14%) at each exposure dose. In C. lacustris-infected sticklebacks, infection rates tended to be highest after exposure to 12 C. lacustris larvae and lowest after exposure to 24 parasites. In A. crassus-infected sticklebacks, no effect of parasite exposure dose on infection rates was observed. Immunity parameters such as respiratory burst activity and lymphocyte proliferation of head kidney leukocytes recorded 18 wk post exposure were not significantly affected by either parasite or exposure dose. Granulocyte:lymphocyte ratios were elevated only within the stickleback group showing the highest infection intensity of C. lacustris, i.e. to those exposed 18 parasites.

Increased risk of acute myeloid leukaemia after treatment for breast cancer

This study evaluates the risk of acute myeloid leukaemia (AML) in patients treated for breast cancer. We included all 6360 breast cancer patients that were recorded at the Geneva Cancer Registry between 1970 and 1999. Patients were followed for AML occurrence until December 2000. We calculated standardized incidence ratios of AML and identified factors modifying the risk of AML by multivariate Cox analysis. Twelve (0.2%) patients developed AML. In general, patients treated for breast cancer had a 3.5-fold (95% confidence interval (CI): 1.8-6.0) increased risk of developing AML compared with the general population. In particular, patients who were older than 70 years at breast cancer diagnosis and those treated with radiotherapy (with or without chemotherapy) had a significantly increased risk of developing AML. This population-based study confirms that radiotherapy increases the risk of AML. Due to the relatively low number of women treated with chemotherapy without radiotherapy and due to the infrequency of the disease, the question of whether chemotherapy alone increases this risk of AML cannot yet be answered.

Local differences in immunocompetence reflect resistance of sticklebacks against the eye fluke Diplostomum pseudospathaceum

We investigated population differences in immunological adaptation of three-spined sticklebacks (Gasterosteus aculeatus) to one of their most abundant macroparasites, the eye fluke Diplostomum pseudospathaceum. We compared infection success in lab-bred fish of 2 populations in northern Germany, from a lake, where eye flukes are prevalent, and a river, where these parasites do not occur. In order to discriminate between protection through innate and acquired immunity, we exposed fish either only once or repeatedly. Lake fish were significantly less susceptible than river sticklebacks already after a single exposure, indicating that in sympatric hosts innate immunity plays the major role in the defence against this helminth infection. In both habitat types, previous exposures only marginally decreased infection rates within 12 weeks. Lake fish showed higher immunocompentence by means of respiratory burst activity and spleen size, regardless of the infection status. Furthermore, they were in a better energy status than river fish, as indicated by a higher hepatosomatic index and haematocrit value. Interestingly, F1 hybrid fish of both populations ranged between the pure habitat types in parasite susceptibility as well as in immunological and condition parameters. Our results suggest that sticklebacks from lakes are better adapted to cope with higher parasite abundance in this habitat.

Genetic variation in MHC class II expression and interactions with MHC sequence polymorphism in three-spined sticklebacks

Genes of the major histocompatibility complex (MHC) have been studied for several decades because of their pronounced allelic polymorphism. Structural allelic polymorphism is, however, not the only source of variability subjected to natural selection. Genetic variation may also exist in gene expression patterns. Here, we show that in a natural population of three-spined sticklebacks (Gasterosteus aculeatus) the expression of MHC class IIB genes was positively correlated with parasite load, which indicates increased immune activation of the MHC when infections are frequent. To experimentally study MHC expression, we used laboratory-bred sticklebacks that were exposed to three naturally occurring species of parasite. We found strong differences in MHC class IIB expression patterns among fish families, which were consistent over two generations, thus demonstrating a genetic component. The average number of MHC class IIB sequence variants within families was negatively correlated to the MHC expression level suggesting compensatory up-regulation in fish with a low (i.e. suboptimal) MHC sequence variability. The observed differences among families and the negative correlation with individual sequence diversity imply that MHC expression is evolutionary relevant for the onset and control of the immune response in natural populations.