Location: Animal Parasitic Diseases Laboratory
2021 Annual Report
Objectives
Objective 1. Determine the change in the intestinal metabolome and microbiome during parasitic nematode infection and after anti-parasitic clearance.
Sub-objective #1. Characterize parasite-induced molecular mechanisms that modulate intestinal inflammation.
Sub-objective #2. Evaluate the potential impact of Cry5B on the native and parasitized gut microbiome.
Objective 2. Identify pan-nematode secretome products with immune modulating activity that along with nutritional supplements eliminate parasites and enhance enteric health.
Sub-objective #1. Use antibodies from parasite infected pigs and goats to select for immunogenic cloned parasite products that have been computationally identified as vaccine targets.
Sub-objective #2: Test for cloned parasite products that induce innate immune responses at the mucosal surface of explanted intestinal tissues from pigs and goats.
Approach
Objective 1. Determine the change in the intestinal metabolome and microbiome during parasitic nematode infection and after anti-parasitic clearance.
Sub-objective #1. Characterize parasite-induced molecular mechanisms that modulate intestinal inflammation.
Hypothesis #1: Parasitic infections alter the relative abundance of butyrate-producing bacteria in the gut and change the composition and concentration of total short-chain fatty acids (SCFA) as well as anti-inflammatory butyrate, which in turn modulates intestinal inflammation and host immunity.
Sub-objective #2. Evaluate the potential impact of Cry5B on the native and parasitized gut microbiome.
Hypothesis #2: The administration of the Cry5B anthelmintic will have minimal effects on the native microbial community in the gut due to its transient nature and invertebrate gut targets.
Hypothesis #3: Parasite-induced changes in the microbiome will be restored to the native structure and function after treatment with Cry5B that reduces worm burden.
Experimental design: Quantifying changes in the intestinal metabolome and gut microbiome induced by parasitic infection, and characterizing the abilities of anti-parasitic treatments to restore altered gut microbiota, are important in dissecting mechanisms of host pathophysiology and immunity. We will conduct an in-depth comparison of the gut metabolome and microbiome between animals randomly assigned to two conditions (naive and infected) and exposed to Cry5B in an optimally determined delivery system.
Objective 2. Identify pan-nematode secretome products with immune modulating activity that along with nutritional supplements eliminate parasites and enhance enteric health.
Sub-objective #1. Use antibodies from parasite infected pigs and goats to select for immunogenic cloned parasite products that have been computationally identified as vaccine targets.
Hypothesis #1: Immunization of target host species with computationally selected immunogenic cloned parasite products will disrupt parasitism and prevent infections.
Sub-objective #2: Test for cloned parasite products that induce innate immune responses at the mucosal surface of explanted intestinal tissues from pigs and goats.
Hypothesis #2: Selected cloned immunogens that also have innate immune features defined by responses in intestinal explants will enhance vaccine efficacy and disrupt parasitism.
Experimental design:
Powerful new technologies to characterize the transcriptomes from multiple life stages of parasitic nematodes (Heizer et al., 2013) can be used to predict secreted peptides common to the pan-secretome. Combining this bioinformatics approach with antibody detection systems of immune peptides and innate responses of intestinal explanted tissues from pigs and goats will be used to identify vaccine candidates for immunization in the target host species of interest.
Progress Report
Probiotic feeding had a minimal impact on native rumen microbiota. The rumen is an important organ where microbial fermentation converts plant fiber into short-chain fatty acids for meat and dairy production. Moreover, approximately 3% of microbes in the rumen, methanogens, are responsible for methane emission, producing the equivalent of 3.1 gigatons of carbon dioxide released into the atmosphere annually. Probiotics have been widely used in livestock production to improve rumen function, including inhibiting methanogens to reduce the environmental footprints of ruminant farming. However, little is known about the unintended effect of probiotic feeding on the native microbial community of the rumen and hindgut. Therefore, ARS researchers in Beltsville, Maryland, conducted a longitudinal (and repeated) sampling of the rumen liquid via rumen cannula in mid-lactation dairy cows and analyzed the rumen microbiome dynamics after probiotic feeding advanced network algorithms and machine learning tools. The findings from this study suggest that frequent probiotic feeding neither had a significant impact on native rumen microbial communities nor disrupted normal rumen function.
Accomplishments
1. Grass-fed beef from the inside out. Increasingly consumers crave grass-fed beef for its health benefits, which include less and healthier fats. However, the environmental cost to completely switch from grain-fed to grass-fed cattle production is prohibitive. USDA researchers in Beltsville, Maryland, worked with the University of Maryland to compare grass- and grain-fed cattle digestion. The gut of grass-fed cattle harbored greater microbial diversity and fewer inflammatory bacteria. Several primary bile acids were enriched in grass-fed cattle. The team discovered microbial signatures that enable producers, veterinarians, and feed companies to improve grass-fed cattle production efficiency while balancing environmental costs.
2. Better control for livestock roundworms. Roundworms infect livestock and people. Ascaris, for example, kills ~ 200,000 people each year. Drug resistance foils conventional treatment and control efforts. Few alternatives are available. Therefore, ARS scientists in Beltsville, Maryland, worked with university researchers to test a new control strategy. Using a food-grade essential oil-based inactivation method, the team made an inexpensive, safe, and stable formulation of probiotic bacteria that express the parasiticidal crystal protein. A single dose eliminated ~ 96% of the roundworms in pigs. Treated foals stopped shedding eggs of Parascaris. This breakthrough enables mass production for rapid commercialization, which may revolutionize ascarid control, benefitting humans and livestock health.
3. Better dewormers for small ruminants. Drug resistance cripples attempts to deworm sheep and goats. Veterinarians and farmers urgently need new tools. Therefore, ARS researchers in Beltsville, Maryland, worked with university collaborators to refine a new, safe, cost-effective method to produce a potent therapy, Inactivated Bacterium with Cytosolic Crystals. In sheep, three doses reduced the number of eggs shed (by 90%), the total number of worms (by 72%), and the number of female worms (by 96%). Biologists think worms will face difficulty evolving resistance to this therapy. Once commercialized, this approach has enormous potential to benefit livestock producers.
Review Publications
Sanders, J., Xie, Y., Gazzola, D., Li, H., Abraham, A., Flanagan, K., Rus, F., Miller, M., Hu, Y., Zarlenga, D.S., Li, R.W., Urban Jr, J.F., Ostroff, G., Zajac, A., Aroian, R.V. 2020. New paraprobiotic-based treatment for control of the barber pole worm Haemonchus contortus in sheep. International Journal for Parasitology: Drug and Drug Resistance. 14(230-236). https://doi.org/10.1016/j.ijpddr.2020.11.004.
Oliveira De Andrade, F., Liu, F., Zhang, X., Mariana, R., Dani, C., Cruz, I., Wang, T.T., Helferiche, W., Li, R.W., Hilakivi-Clarke, L. 2021. Genistein reduces the risk of local mammary cancer recurrence and ameliorates alterations in the gut microbiota in the offspring of obese dams. Nutrients. 12(1):201. https://doi.org/10.3390/nu13010201.
Oh, S., Li, R.W. 2021. Temporal dynamic methods for bulk RNA-Seq time series data. Genes. 12(3):352. https://doi.org/10.3390/genes12030352.
Cao, W., Chin, Y., Li, R.W., Xue, C., Wang, Y., Tang, Q. 2021. Transcriptome analysis reveals the protective role of fructo-oligosaccharide in colonic mucosal barriers in exercise-induced stressed mice. Food and Function. https://doi.org/10.1039/D0FO02556A.
Dong, X., Wang, X., Liu, F., Li, R.W., Xue, C., Wong, K., Wong, W., Tang, Q. 2020. Polymannuronic acid prevents dopaminergic neuronal loss via brain-gut-microbiota axis in Parkinson’s disease model. International Journal of Biological Macromolecules. 164:994-1005. https://doi.org/10.1016/j.ijbiomac.2020.07.180.
Urban Jr, J.F., Nielsen, M., Gazzola, D., Xie, Y., Beshah, E., Hu, Y., Rus, F., Flanagan, K., Draper, A., Vakalapudi, S., Li, R.W., Ostroff, G.R., Aroian, R.V. 2020. An inactivated bacterium (paraprobiotic) expressing Bacillus thuringiensis Cry5B as a therapeutic for Ascaris and Parascaris spp. infections in large animals. Elsevier. 164:994-1005. https://doi.org/10.1016/j.onehlt.2021.100241.
