What is new in the swine group from the UMN CVM
In this new scientific publication from Dr. Jorge Garrido, PhD candidate from the Torremorell lab, numerous sampling strategies to monitor influenza were compared. the following individual, litter, and environmental samples were included in the study:
A new scientific article from the Torremorell lab, about the influence of maternal antibodies on influenza dynamics was published in PLoS ONE.
The study followed 10 cohorts of nursery piglets form a single influenza-positive sow farm and compared influenza dynamics based on the vaccination status of the dam.
Continue reading “Effect of strain-specific maternally-derived antibodies on influenza A virus infection dynamics in nursery pigs”In this paper published in the Journal of Veterinary Diagnostic Investigation, PhD-candidate Talita Resende from Dr. Vannucci’s lab, shares a novel diagnostic technique to detect various rotavirus species using newly developed markers.
Continue reading “A new diagnostic test to differentiate rotavirus subtypes”Today, we are sharing an original research article published by the MycoLab and Dr. Maria Pieters in PLOS One regarding detection patterns for 2 species of mycoplasmas in sows and piglets.
The objectives of this study were to:
Under the conditions of this investigation, dams appeared to be consistently positive for both M. hyorhinis and M. hyosynoviae prior to weaning.
In contrast, higher detection was observed in piglets at week 3, in comparison to week 1 post-farrowing, with M. hyorhinis, while detection of M. hyosynoviae was remarkably minimal.
The relative risk of developing lameness in postweaning piglets was highly associated with the detection of M. hyorhinis at 3 weeks of age
This research article is available in open-access on the PlOS One website.
Continue reading “Mycoplasma hyorhinis and Mycoplasma hyosynoviae dual detection patterns in dams and piglets”Today, we are sharing a publication by Dr. Talita Resende, a phD candidate working with Drs. Gebhart and Vannucci. Dr. Resende’s research focuses on the mechanisms enabling Lawsonia intracellularis’ infectivity and pathogenesis. Her latest paper, available in open access from Veterinary Microbiology, looks at the effects of Lawsonia intracellularis on different cell lines.
4 different intestinal epithelial cells lines were compared in this study: IPEC-J2 , IEC-18, Caco-2, and McCoy cells. McCoy were used as a reference since previous publications have shown that Lawsonia intracellularis can grow in this cell type.
Each cell line was infected with 2 types of Lawsonia intracellularis: low and high passage. Infected cell lines were used as control during the experiment. At days 1, 4, and 7 post-infection, the number of cells highly infected by Lawsonia (i.e. that had more than 30 organisms in their cytoplasm) was counted. To estimate cell proliferation, the amount of DNA in each cell line was evaluated. Additionally, a fluoerescence marker called Ki-67 was used to identified eukaryotic cells undergoing division. Lastly, a wound closure assay was done by scraping infected cell lines with a pipette and measure the width of the “wound” over time.
All cell lines tested were susceptible to L. intracellularis infection with typical intracellular bacterial growth of about 30–100 per cell in the cytoplasm of infected cells.
There was no statistical difference in cellular proliferation within or among groups at 0 and 1 dpi. Additionally, no increased proliferation in any cell line infected by L. intracellularis was noted, regardless of the bacterial passage status.
To verify whether cells infected by L. intracellularis would proliferate and migrate faster than non-infected cells through a scratched monolayer, a wound closure assay was executed. There were no differences among treatment groups for wound closure at any time point (0 to 24h and 24h to 48h)
It is suggested that L. intracellularis preferentially infects actively proliferating cells in intestinal crypts. By looking at both Lawsonia and Ki-67 markers, it was noted that in the majority of treatment groups and with the exception of the IPEC-J2 cell line, the proportion of cells that were double positive (L. intracellularis was co-localized with Ki-67) was higher than cells that were L. intracellularisinfected, but negative for Ki-67.
Taken together, these findings have decisively shown that two-dimensional intestinal epithelial in vitro cultures do not reproduce the characteristic proliferative effect of L. intracellularis infection in vivo.
Lawsonia intracellularis is an obligate intracellular bacterium that causes proliferative enteropathy in various animal species. While cellular proliferation of intestinal cells is recognized as the hallmark of L. intracellularis infection in vivo, it has not been demonstrated in in vitromodels. In order to assay the effect of L. intracellularis, various cell lines were infected with pathogenic and non-pathogenic passages of the bacterium. Because of the high proliferative rate of these cell lines, serum deprivation, which is known to reduce proliferation, was applied to each of the cell lines to allow the observation of proliferation induced by L. intracellularis. Using antibodies for Ki-67 and L. intracellularis in dual immunofluorescence staining, we observed that L. intracellularis was more frequently observed in proliferating cells. Based on wound closure assays and on the amount of eukaryotic DNA content measured over time, we found no indication that cell lines infected with L. intracellularis increased proliferation and migration when compared to non-infected cells (p > 0.05). Cell arrest due to decreased serum in the culture media was cell-line dependent. Taken together, our findings provide data to support and expand previous subjective observations of the absence of in vitro proliferation caused by L. intracellularis in cell cultures and confirm that cell lines infected by L. intracellularis fail to serve as adequate models for understanding the cellular changes observed in proliferative enteropathy-affected intestines.