FAILURE OF TRANSMISSION OF LOW-PATHOGENIC AVIAN INFLUENZA VIRUS BETWEEN MALLARDS AND FRESHWATER SNAILS: AN EXPERIMENTAL EVALUATION

In aquatic bird populations, the ability of avian influenza (AI) viruses to remain infectious in water for extended periods provides a mechanism that allows viral transmission to occur long after shedding birds have left the area. However, this also exposes other aquatic organisms, including freshwater invertebrates, to AI viruses. Previous researchers found that AI viral RNA can be sequestered in snail tissues. Using an experimental approach, we determined whether freshwater snails (Physa acuta and Physa gyrina) can infect waterfowl with AI viruses by serving as a means of transmission between infected and naı¨ve waterfowl via ingestion. In our first experiment, we exposed 20 Physa spp. snails to an AI virus (H3N8) and inoculated embryonated specific pathogen–free (SPF) chicken eggs with the homogenized snail tissues. Sequestered AI viruses remain infectious in snail tissues; 10% of the exposed snail tissues infected SPF eggs. In a second experiment, we exposed snails to water contaminated with feces of AI virus–inoculated Mallards (Anas platyrhynchos) to evaluate whether ingestion of exposed freshwater snails was an alternate route of AI virus transmission to waterfowl. None of the immunologically naı¨ve Mallards developed an infection, indicating that transmission via ingestion likely did not occur. Our results suggest that this particular trophic interaction may not play an important role in the transmission of AI viruses in aquatic habitats

Do Study Abroad Programs Enhance the Employability of Graduates?

Using data on a large sample of recent Italian graduates, this paper investigates the extent to which participation in study abroad programs during university studies impacts subsequent employment likelihood. To address the problem of endogeneity related to participation in study abroad programs, I use a combination of fixed effects and instrumental variable estimation where the instrumental variable is exposure to international student exchange schemes. My estimates show that studying abroad has a relatively large and statistically meaningful effect on the probability of being in employment three years after graduation. This effect is mainly driven by the impact that study abroad programs have on the employment prospects of graduates from disadvantaged (but not very disadvantaged) backgrounds, though positive but imprecise effects are also found for graduates from advantaged backgrounds

Nod-like receptors modulate neonatal infection-induced microbiota-gut-brain axis deficits

Diarrheal diseases, such as those caused by enteric pathogens, including Enteropathogenic E. coli (EPEC), pose a significant problem in developing countries. In prior studies, we found that neonatal infection-induced disruption of colonization of the gut microbiome causes long-term impacts on microbiota-gut-brain (MGB) axis signaling in mice. Additional studies have also demonstrated a crucial role for innate immune Nod-like receptors (NLRs) expressed on intestinal epithelial cells (IEC), which recognize bacterial peptidoglycan (PGN), in regulating stress-induced behavioral deficits. We therefore hypothesized that IEC Nod1 receptors, activated by EPEC-derived PGN, modulate disrupted MGB axis signaling following early-life infection. On postnatal day (P)7, Villin Cre+ (Nod1ΔIEC) and littermate Cre- (WT) mice were infected with EPEC (or vehicle control [Luria Bertani broth]). Acute gastrointestinal (GI) inflammation, histological damage, and EPEC colonization were assessed at 1-week post-infection (P14) and behavior, inflammation (ileum, hippocampus), serum corticosterone, and neurogenesis were assessed in adulthood (P42-56). We found that the absence of IEC Nod1 receptors prevents EPEC-induced GI inflammation and altered IEC kinetics at P14, with no impact on bacterial burden. This was coupled with an absence of EPEC-induced altered hippocampal neurogenesis and neuroinflammation in adulthood, both known to regulate cognitive function. Increased serum corticosterone levels were also found in adult mice following early-life infection, suggesting stress may modulate impairments along the MGB axis via IEC Nod1 receptors. Finally, to investigate a potential therapeutic, we administered probiotic bacteria-derived muropeptides to neonatal mice for 7 days following EPEC infection (P7-14). In preliminary studies, we found a potential role for muropeptides in ameliorating EPEC-induced GI inflammation through increased anti-inflammatory cytokine expression. Taken together, these results demonstrate a novel role for IEC Nod1 receptors in modulating EPEC-induced MGB axis dysregulation

Evaluation of an adjuvanted hapten-protein vaccine approach to preventing sexual maturation of farmed Atlantic salmon

2013 Fall.Includes bibliographical references.Aquaculture is a rapidly growing industry that significantly contributes to the world food supply. Sustainable practices in aquaculture are of increasing importance as an increasing proportion of fish in the global market come from aquaculture instead of wild catch. Maximizing aquaculture yields and minimizing the ecological impacts of these operations are two important goals towards sustainability. One approach to addressing these objectives is immunocontraception of fish which would increase the fish meat quality and yield in aquaculture production and prevent escaped farmed fish from undesirably altering wild fish population genetics through breeding. The research presented here was conducted with the aim of proof of concept for contraceptive vaccine use in Atlantic salmon. Nine vaccine formulations, including a negative control vaccine, were formulated at the National Wildlife Research Center in Fort Collins, Colorado and injected into farmed Atlantic salmon in Sunndalsøra, Norway. Production of antibodies against three immunogenic components in each vaccine formulation was evaluated over the course of the 12-week study. Weight and length of each fish were also tracked over time to determine whether growth was affected by vaccination. The study results indicate that Atlantic salmon will produce antibodies against BSA and KLH used as carrier proteins but that KLH is a stronger immunogen. Importantly, it was also determined that Atlantic salmon will produce antibodies against a small endogenous peptide (hapten) conjugated to the carrier protein, but to a lesser extent than the levels of antibody production against the carrier itself. Approximately 96% of samples from fish vaccinated against KLH, 76% of samples from fish vaccinated against BSA, and 36% of samples from fish vaccinated against the hapten were identified as positive. Response rates for all three antigens were highest 12 weeks post-vaccination. Significant differences in antibody levels were also detected between groups vaccinated with different immunostimulants. Collectively, the results provide proof of concept and provide a building block for further research on immunocontraception of Atlantic salmon for application in aquaculture

An evaluation of the Indiana Mathematics Contest Program

Not Available.Charles A. OrahoodNot ListedNot ListedMaster of ScienceDepartment Not ListedCunningham Memorial Library, Terre Haute, Indiana State University.isua-thesis-1953-orahoodMastersTitle from document title page. Document formatted into pages: 46p. :ill. Includes appendi

Shedding and serologic responses following primary and secondary inoculation of house sparrows (\u3ci\u3ePasser domesticus\u3c/i\u3e) and European starlings (\u3ci\u3eSturnus vulgaris\u3c/i\u3e) with low-pathogenicity avian influenza virus

Waterfowl and shorebirds are well-recognized natural reservoirs of low-pathogenicity avian influenza viruses (LPAIV); however, little is known about the role of passerines in avian influenza virus ecology. Passerines are abundant, widespread, and commonly come into contact with free-ranging birds as well as captive game birds and poultry. We inoculated and subsequently challenged house sparrows (Passer domesticus) and European starlings (Sturnus vulgaris) with wild-bird origin LPAIV H3N8 to evaluate their potential role in transmission. Oropharyngeal shedding was short lived, and was detected in more starlings (97.2%) than sparrows (47.2%; n = 36 of each). Cloacal shedding was rare in both species (8.3%; n = 36 of each) and no cage-mate transmission occurred. Infectious LPAIV was cultured from oropharyngeal and cloacal swabs and gastrointestinal and respiratory tissues from both species. Seroconversion was detected as early as 3 days post inoculation (d.p.i.) (16.7% of sparrows and 0% of starlings; n = 6 each); 50% of these individuals seroconverted by 5 d.p.i., and nearly all birds (97%; n = 35) seroconverted by 28 d.p.i. In general, pre-existing homologous immunity led to reduced shedding and increased antibody levels within 7 days of challenge. Limited shedding and lack of cage-mate transmission suggest that passerines are not significant reservoirs of LPAIV, although species differences apparently exist. Passerines readily and consistently seroconverted to LPAIV, and therefore inclusion of passerines in epidemiological studies of influenza outbreaks in wildlife and domestic animals may provide further insight into the potential involvement of passerines in avian influenza virus transmission ecology