Our latest addition to the swine group at the University of Minnesota College of Veterinary Medicine is Dr. Matheus Costa whose research interests are in pathogen virulence mechanisms and more specifically swine dysentery and streptococcal meningitis.
Objective: Microbiological and virulence characterization of 2 moderately hemolytic Brachyspira strains.
Materials and methods: Clinical isolates were obtained from diarrheic (3603-F2) and healthy (G79) pigs. Phenotypic characterization included assessment of hemolytic activity on blood agar and biochemical profiling. Genotyping was performed by sequencing the nicotinamide adenine dinucleotide oxidase (nox) gene, whole genome sequencing, and comparison to relevant Brachyspira. Pig inoculation included 4 treatment groups in 2 challenge experiments: negative control (sterile broth media; n = 12), positive control (Brachyspira hampsonii genomovar 2 strain 30446; n = 18), and 3603-F2 (n = 12) or G79 (n = 12). Fecal scoring and rectal swabbing for culture were performed daily. Animals were euthanized following onset of mucohemorrhagic diarrhea or between 21 and 28 days post inoculation (dpi). Gross and microscopic pathology were assessed. Terminal colon samples were used to characterize post-infection mucosal ion secretion.
Results: Both strains were moderately hemolytic. Whole genome and nox sequencing identified 3603-F2 as Brachyspira murdochii and G79 as a novel strain. Both challenge trials revealed intestinal colonization, but no mucohemorrhagic diarrhea. Sporadic watery diarrhea was induced by 3603-F2 associated with a pattern of microscopic lesions similar to pigs with swine dysentery (positive controls). No diarrhea was observed in G79 inoculated pigs, but microscopic lesions were more severe than in controls. Both strains induced greater colonic anion secretory potential than negative controls 21 dpi.
Implications: Allegedly avirulent Brachyspira species most closely related to B murdochii can be associated with subclinical colitis and may be a concern for grow-finish pigs.
This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
The MSHMP team would like to announce changes that will be coming to the weekly report in July, 2019 as we start a new monitoring year. Since mid 2017 we have been working towards switching the MSHMP database and report out of Excel and into a structured query language (SQL) database, with the report created using the programs R and LateX. We will officially make the transition starting July fifth and are excited to introduce you to some of the changes you will be seeing in the upgraded version of the MSHMP report.
The decision to transition into an SQL database and create the report with R and LateX was made primarily for 3 reasons: 1) Storage and query capabilities, 2) Reliability and 3) Automatization of the report generation process. Altogether this will improve the quality and speed of data management to continue to enable the project to grow in a constant manner.
The general contents and layout of the report will remain unaltered. The main change in the report is its overall appearance as the style, detail information and legends have been altered. The SVV chart show now only data from veterinary diagnostic laboratories. PRRSv Chart 3, incidence by Status, has been replaced by a new chart, PRRS Incidence Rate, to better reflect the status frequency of breaks.
The top paragraphs of the PRRSv and PEDv pages have been updated to more clearly reflect how systems are included in charts. We also show the amount of systems reporting each disease for the week out of the total number of systems, rather than out of the total included in a particular chart.
As a team we are very excited to launch our new more reliable and efficient database system and weekly report. We know it will enable our work to continue growing and improving, providing more value to the swine industry and associated communities. As a group we particularly want to acknowledge Post-Doc Juan Sanhueza and our IT Director Paulo Fioravante, the primary architects of the new system, and thank them for the immense amount of work they have done to make this possible.