Effects of fire on the soil microbial ecosystem in a native tallgrass prairie.

Introduction: Fire was once a wide-spread, naturally occurring element that probably contributed to the maintenance of the temperate grasslands in the central United States (Daubenmire, 1968). Native bluestem prairie in the United States produces large amounts of dead vegetation, or mulch, yearly (Weaver & Rowland, 1952; Hopkins, 1954). The immediate effect of fire on the native grasslands is the removal of the mulch layer along with the destruction of growing vegetation. The extent of this activity is determined by the season, intensity, and duration of the fire (Weaver, 1954)

Research Methods and Primary Sources: Writing the History of your Public Health Laboratory

Objective: This study traced the history of the Nebraska Public Health Laboratory (NPHL) since inception in April 1913 to the present time. The significance of knowing the laboratory’s history not only centered around legacy knowledge for the laboratory, but also provided important information on the history of how public health grew and was enforced in Nebraska, especially concerning reportable diseases and specimen collection. Study Design: The historical survey used mostly primary source documents including field notes from public health inspectors, disease reporting databases collected by the state health department and a variety of government documents pertaining to guidelines surrounding reportable diseases and procedures for specimen collection and proper testing techniques. The annual reports of the State Department of Health were also examined. Results: Deciphering the history of the NPHL was challenging but much was learned regarding the role the laboratory played in the process of public health in Nebraska. The correlation of significant health occurrences (e.g. the rise of polio in 1952, the importance of tuberculosis in the state highlighted by a 1939 study) with reporting/laboratory activities was done which showed how these topics have always, and will continue to be, the confirmation health officials need when making appropriate decisions about the public’s health. Conclusions: The challenges of tracing a laboratory’s history are many and can prove to be a difficult puzzle to solve. However, the knowledge obtained with this research can provide insight into the importance of the role the public health laboratory had played. With new diseases appearing and old ones emerging, the laboratory will continue to play a significant role in the future of the public’s health

The First Hundred Years of the Nebraska Public Health Laboratory: A Major Role Played in the Development of Public Health

Public health laboratories are the invisible key to public health. These laboratories have played a significant role in the health of the community since their inception in the late 1800s. They provide confirmation of disease outbreaks and statistics on the health and welfare of the people, with more recent activities in the detection of biological and chemical agents of terrorism. However, the history of these laboratories is mostly unknown. For instance, a recent brief historical account of the Nebraska Department of Health and Human Services did not include information on the state public health laboratory in the timeline of historical events (Nebraska Department of Health and Human Services, p.1). On the eve of the 100th anniversary of the inception of what is now known as the Nebraska Public Health Laboratory (NPHL), we feel compelled to provide this historical account in recognition of the i importance of the laboratory to preserve the health of Nebraskans. Charles Rosen, a noted medical historian, wrote that “the public health laboratory service[s]…[is of] enormous value to the community [and] cannot be exaggerated. The responsibility of the government to protect the health of the people is concretely exemplified in the public health laboratory” (Rosen, p. 311)

Oligomerization of Bacterially Expressed H1N1 Recombinant Hemagglutinin Contributes to Protection Against Viral Challenge

Vaccination is the most effective intervention to prevent influenza and control the spread of the virus. Alternatives are needed to the traditional egg-based vaccine strategy for a more rapid response to new outbreaks. Two different hemagglutinin (HA) fragments (rHA11-326 and rHA153-269) derived from influenza A virus subtype H1N1 were expressed in Escherichia coli and characterized by immunoblot, gel filtration, hemagglutination, and competitive binding assays. rHA11-326 included neutralizing epitopes and the trimerization domain, whereas rHA153-269 included only the head of HA with the neutralizing epitopes. Mice were immunized with rHA11-326 or rHA153-269, and sera were tested for the presence of neutralizing antibodies. Mice were then challenged with H1N1 and infection severity was monitored. rHA11-326 trimerized, whereas rHA153-269 was unable to form oligomers. Both rHA11-326 and rHA153-269 elicited the production of neutralizing antibodies, but only oligomerized rHA11-326 protected against live virus challenges in mice. This study demonstrated that bacterially expressed HA was capable of folding properly and eliciting the production of neutralizing antibodies, and that HA oligomerization contributed to protection against viral challenge. Therefore, prokaryotic-derived vaccine platforms can provide antigenic and structural requirements for viral protection, as well as allow for the rapid and cost-effective incorporation of multiple antigens for broader protection

Hemagglutinin-based polyanhydride nanovaccines against H5N1 influenza elicit protective virus neutralizing titers and cell-mediated immunity

H5N1 avian influenza is a significant global concern with the potential to become the next pandemic threat. Recombinant subunit vaccines are an attractive alternative for pandemic vaccines compared to traditional vaccine technologies. In particular, polyanhydride nanoparticles encapsulating subunit proteins have been shown to enhance humoral and cell-mediated immunity and provide protection upon lethal challenge. In this work, a recombinant H5 hemagglutinin trimer (H53) was produced and encapsulated into polyanhydride nanoparticles. The studies performed indicated that the recombinant H53 antigen was a robust immunogen. Immunizing mice with H53 encapsulated into polyanhydride nanoparticles induced high neutralizing antibody titers and enhanced CD4+ T cell recall responses in mice. Finally, the H53-based polyanhydride nanovaccine induced protective immunity against a low-pathogenic H5N1 viral challenge. Informatics analyses indicated that mice receiving the nanovaccine formulations and subsequently challenged with virus were similar to naïve mice that were not challenged. The current studies provide a basis to further exploit the advantages of polyanhydride nanovaccines in pandemic scenarios

Hemagglutinin-based polyanhydride nanovaccines against H5N1 influenza elicit protective virus neutralizing titers and cell-mediated immunity.

H5N1 avian influenza is a significant global concern with the potential to become the next pandemic threat. Recombinant subunit vaccines are an attractive alternative for pandemic vaccines compared to traditional vaccine technologies. In particular, polyanhydride nanoparticles encapsulating subunit proteins have been shown to enhance humoral and cell-mediated immunity and provide protection upon lethal challenge. In this work, a recombinant H5 hemagglutinin trimer (H5₃) was produced and encapsulated into polyanhydride nanoparticles. The studies performed indicated that the recombinant H5₃ antigen was a robust immunogen. Immunizing mice with H5₃ encapsulated into polyanhydride nanoparticles induced high neutralizing antibody titers and enhanced CD4(+) T cell recall responses in mice. Finally, the H5₃-based polyanhydride nanovaccine induced protective immunity against a low-pathogenic H5N1 viral challenge. Informatics analyses indicated that mice receiving the nanovaccine formulations and subsequently challenged with virus were similar to naïve mice that were not challenged. The current studies provide a basis to further exploit the advantages of polyanhydride nanovaccines in pandemic scenarios

Susceptibility of hamsters to clostridium difficile isolates of differing toxinotype

Clostridium difficile is the most commonly associated cause of antibiotic associated disease (AAD), which caused ~21,000 cases of AAD in 2011 in the U.K. alone. The golden Syrian hamster model of CDI is an acute model displaying many of the clinical features of C. difficile disease. Using this model we characterised three clinical strains of C. difficile, all differing in toxinotype; CD1342 (PaLoc negative), M68 (toxinotype VIII) and BI-7 (toxinotype III). The naturally occurring non-toxic strain colonised all hamsters within 1-day post challenge (d.p.c.) with high-levels of spores being shed in the faeces of animals that appeared well throughout the entire experiment. However, some changes including increased neutrophil influx and unclotted red blood cells were observed at early time points despite the fact that the known C. difficile toxins (TcdA, TcdB and CDT) are absent from the genome. In contrast, hamsters challenged with strain M68 resulted in a 45% mortality rate, with those that survived challenge remaining highly colonised. It is currently unclear why some hamsters survive infection, as bacterial and toxin levels and histology scores were similar to those culled at a similar time-point. Hamsters challenged with strain BI-7 resulted in a rapid fatal infection in 100% of the hamsters approximately 26 hr post challenge. Severe caecal pathology, including transmural neutrophil infiltrates and extensive submucosal damage correlated with high levels of toxin measured in gut filtrates ex vivo. These data describes the infection kinetics and disease outcomes of 3 clinical C. difficile isolates differing in toxin carriage and provides additional insights to the role of each toxin in disease progression

A Role for TLR4 in Clostridium difficile Infection and the Recognition of Surface Layer Proteins

Clostridium difficile is the etiological agent of antibiotic-associated diarrhoea (AAD) and pseudomembranous colitis in humans. The role of the surface layer proteins (SLPs) in this disease has not yet been fully explored. The aim of this study was to investigate a role for SLPs in the recognition of C. difficile and the subsequent activation of the immune system. Bone marrow derived dendritic cells (DCs) exposed to SLPs were assessed for production of inflammatory cytokines, expression of cell surface markers and their ability to generate T helper (Th) cell responses. DCs isolated from C3H/HeN and C3H/HeJ mice were used in order to examine whether SLPs are recognised by TLR4. The role of TLR4 in infection was examined in TLR4-deficient mice. SLPs induced maturation of DCs characterised by production of IL-12, TNFα and IL-10 and expression of MHC class II, CD40, CD80 and CD86. Furthermore, SLP-activated DCs generated Th cells producing IFNγ and IL-17. SLPs were unable to activate DCs isolated from TLR4-mutant C3H/HeJ mice and failed to induce a subsequent Th cell response. TLR4−/− and Myd88−/−, but not TRIF−/− mice were more susceptible than wild-type mice to C. difficile infection. Furthermore, SLPs activated NFκB, but not IRF3, downstream of TLR4. Our results indicate that SLPs isolated from C. difficile can activate innate and adaptive immunity and that these effects are mediated by TLR4, with TLR4 having a functional role in experimental C. difficile infection. This suggests an important role for SLPs in the recognition of C. difficile by the immune system