2009 Annual Report
Identifying PRRSV genotypes that confer fitness in macrophages, and host genes that respond to PRRSV fitness, to provide novel targets for intervention and control of PRRSV infections. These studies will use adapted isolates to identify viral genotypes that correlate with fitness of PRRSV in porcine alveolar macrophages and corresponding changes in macrophage transcriptional profiles.
Genetic variation in specific ovine genes influences predisposition to ovine lentivirus (OLV) and the associated disease, ovine progressive pneumonia (OPP). We will thoroughly evaluate the most obvious candidate genomic regions for effects on lentiviral disease, like that containing CCR5. Our aim is to evaluate important regions of the genome for allelic association with the OLV disease susceptibility and progression phenotypes. Selection of regions will be based on a variety of scientific observations including, but not limited to, comparative mammalian biology.
A selected set of 90 single nucleotide polymorphism (SNP) markers will be identified that are highly-informative in beef and dairy cattle. The development of this marker set represents non-hypothesis-driven research. The markers and genotyping assays for the markers will be readily available for any traceback needs. The same markers are also ideal for animal identification (i.e., sample matching) and routine parentage analysis. After ear tags and other physical identification devices have been removed, an animal’s DNA remains as a stable, accessible, integral, and identifiable component of its products and, thus, provides a gold standard for auditing the fidelity of physical labels and associated records.
BRDC is composed of an assortment of bacterial and viral pathogens. One of these bacteria, Mannheimia haemolytica (formerly Pasteurella haemolytica), causes pneumonia in ruminants and produces a leukotoxin that is cytotoxic only for ruminant leukocytes (white blood cells). When viral and bacterial agents break down the antimicrobial barrier in the lungs, M. haemolytica--which is usually a commensal organism--can become pathogenic.
In collaboration with scientists in the Department of Veterinary Biosciences at the University of Nebraska – Lincoln, we have initiated in vitro studies using bovine macrophages infected with M. haemolytica to determine if we can alter the levels of leukotoxin produced under different cell-culture conditions. We have determined that succinate is an important metabolite in the growth of M. haemolytica that can be used in place of supplemental serum in macrophage/bacterial cultures. We plan to exploit this finding in future metabolic studies of this important bovine pathogen.
In collaboration with scientists in the Department of Homeland Security (DHS), U. S. Meat Animal Research Center (USMARC) scientists have been testing bovine, ovine, and porcine cell lines developed at USMARC for their suitability to support protein expression of a Foot and Mouth Disease (FMD) molecular vaccine. Four cell lines (MARC-BGCF2, MARC-BOE, Cdelta 2+, and Cdelta 2-) were screened by electron microscopy (EM) for their ability to support FMD protein expression; unfortunately, none of the cell lines supported detectable protein expression. These same four cell lines were screened using EM and virus isolation for their ability to support FMD virus (FMDV) expression. Cells were infected with two different FMDV strains. One of the cell lines, MARC-BOE, supported excellent replication of one of the FMDV isolates. Virus titers were similar to that achieved in the gold-standard cell line currently used for FMDV propagation.
Development of informatics for studying the transcriptome of swine infected by porcine reproductive and respiratory syndrome virus (PRRSV). Collaborated with scientists at the National Animal Disease Center (NADC) to investigate the genes involved in the progression of PRSSV in infected swine. Scientists at NADC and USMARC were awarded a National Pork Board grant (effective 11/01/2008 to 11/01/2010) entitled “Gene expression in lymph nodes of PRRSV-infected pigs,” CRIS Project: 3625-32000-088-28R. Over the past year, NADC and USMARC scientists have collaborated to coordinate the collection of data generated from this grant at NADC with its analysis at USMARC. NADC and USMARC scientists have adapted pre-existing data processing pipelines to analyze transcriptomic data from this project to gain new insights into the molecular mechanisms involved in PRRSV infection.
Kijas, J.W., Townley, D., Dalrymple, B.P., Heaton, M.P., Maddox, J.F., McGrath, A., Wilson, P., Ingersoll, R.G., McCulloch, R., McWilliam, S., Tang, D., McEwan, J., Cockett, N., Oddy, V.H., Nicholas, F.W., Raadsma, H. 2009. A Genome Wide Survey of SNP Variation Reveals the Genetic Structure of Sheep Breeds. PLoS One [serial online]. 4(3):e4668. Available: http://www.plosone.org.
Elsik, C.G., Gibbs, R., Skow, L., Tellam, R., Weinstock, G., Worley, K., Kappes, S.M., Green, R.D., Alexander, L.J., Bennett, G.L., Carroll, J.A., Chitko Mckown, C.G., Hamernik, D.L., Harhay, G.P., Keele, J.W., Liu, G., Macneil, M.D., Matukumalli, L.K., Rijnkels, M., Roberts, A.J., Smith, T.P., Snelling, W.M., Stone, R.T., Waterman, R.C., White, S.N. 2009. The Genome Sequence of Taurine Cattle: A Window to Ruminant Biology and Evolution. Science. 324:522-528.
Matukumalli, L.K., Lawley, C.T., Schnabel, R.D., Taylor, J.F., Allan, M.F., Heaton, M.P., O'Connell, J., Moore, S.S., Smith, T.P., Sonstegard, T.S., Van Tassell, C.P. 2009. Development and Characterization of a High Density SNP Genotyping Assay for Cattle. PLoS One. 4(4):e5350. Available: http://dx.doi.org/10.1371/journal.pone.0005350.
Clawson, M.L., Keen, J.E., Smith, T.P., Durso, L.M., Mcdaneld, T.G., Mandrell, R.E., Davis, M.A., Bono, J.L. 2009. Phylogenetic Classification of Escherichia coli O157:H7 Strains of Human and Bovine Origin Using a Novel Set of Nucleotide Polymorphisms. Genome Biology [serial online]. 10:R56. Available: http://genomebiology.com/2009/10/5/R56.