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This report describes the fetoplacental pathology of Chlamydia psittaci-associated abortion, premature birth, and neonatal loss in 46 of 442 equine abortion investigations between 2015 and 2019. Seven abortions, 26 premature births, and 13 neonatal deaths with positive C. psittaci polymerase chain reaction (PCR) were evaluated. In 83% of cases (38/46), C. psittaci infection was considered as the primary cause of loss based on quantitative PCR (qPCR) confirmation, pathological findings, and exclusion of other causes, and was supported by Chlamydia spp immunolabeling in fetoplacental lesions. Lymphohistiocytic placentitis with vasculitis (36/38) affected the amnion, umbilical cord, and chorioallantois at the umbilical vessel insertion and/or cervical pole. Lymphohistiocytic chorionitis in the subvillous stroma extended to the allantois mostly without villous destruction. Lymphohistiocytic amnionitis and funisitis occurred at the amniotic cord attachment. Lymphohistiocytic hepatitis was observed in 19/38 cases and pneumonia was identified in 26 cases. Chlamydia spp immunolabeled in placenta, lung, liver, or splenic tissue in the cases that were tested (14/38). C. psittaci infection was not the cause of loss in 2 cases with other diseases and of uncertain significance in 6 cases with no conclusive cause of loss. immunohistochemistry (IHC) was negative for 6 of these cases (6/8). The highest Chlamydia load was detected in pooled placental tissues by qPCR. qPCR and IHC had 83% congruence at a qPCR cut-off of 1 gene copy. IHC limits of detection corresponded to infections with 2 × 102 gene copies identified by qPCR. This study confirms the etiological role of C. psittaci as a cause of naturally occurring equine reproductive loss.

Supplemental material, sj-pdf-1-vet-10.1177_03009858221120008 for Fetoplacental pathology of equine abortion, premature birth, and neonatal loss due to Chlamydia psittaci by Angela P. Begg, Joan Carrick, Catherine Chicken, Anna Blishen, Kristen Todhunter, Kieran Eamens and Cheryl Jenkins in Veterinary Pathology

Background C. psittaci has recently emerged as an equine abortigenic pathogen causing significant losses to the Australian Thoroughbred industry, while Equine herpesvirus-1 (EHV-1) is a well-recognized abortigenic agent. Diagnosis of these agents is based on molecular assays in diagnostic laboratories. In this study, we validated C. psittaci and newly developed EHV-1 Loop Mediated Isothermal Amplification (LAMP) assays performed in a real-time fluorometer (rtLAMP) against the reference diagnostic assays. We also evaluated isothermal amplification using commercially available colorimetric mix (cLAMP), and SYBR Green DNA binding dye (sgLAMP) for “naked eye” end-point detection when testing ‘real-world’ clinical samples. Finally, we applied the C. psittaci LAMP assays in two pilot Point-of-Care (POC) studies in an equine hospital. Results The analytical sensitivity of C. psittaci and EHV-1 rt-, and colorimetric LAMPs was determined as one and 10 genome equivalents per reaction, respectively. Compared to reference diagnostic qPCR assays, the C. psittaci rtLAMP showed sensitivity of 100%, specificity of 97.5, and 98.86% agreement, while EHV-1 rtLAMP showed 86.96% sensitivity, 100% specificity, and 91.43% agreement. When testing rapidly processed clinical samples, all three C. psittaci rt-, c-, sg-LAMP assays were highly congruent with each other, with Kappa values of 0. 906 for sgLAMP and 0. 821 for cLAMP when compared to rtLAMP. EHV-1 testing also revealed high congruence between the assays, with Kappa values of 0.784 for cLAMP and 0.638 for sgLAMP when compared to rtLAMP. The congruence between LAMP assays and the C. psittaci or EHV-1 qPCR assays was high, with agreements ranging from 94.12 to 100% for C. psittaci, and 88.24 to 94.12% for EHV-1, respectively. At the POC, the C. psittaci rt- and c-LAMP assays using rapidly processed swabs were performed by technicians with no prior molecular experience, and the overall congruence between the POC C. psittaci LAMPs and the qPCR assays ranged between 90.91–100%. Conclusions This study describes reliable POC options for the detection of the equine pathogens: C. psittaci and EHV-1. Testing ‘real-world’ samples in equine clinical setting, represents a proof-of-concept that POC isothermal diagnostics can be applied to rapid disease screening in the equine industry.

Molecular electronics is currently the focus of much research, since the minimization limit of conventional field effect transistors is gradually being reached. The ultimate goal of molecular electronics is to form functional electronic components from single molecules. There are two main challenges to reaching this goal: gaining control over the electronic properties of the molecule and gaining control over the geometric configuration of the molecule. Many experimental investigations of electron transport through molecules have been carried out in the past decades. However if the geometry of the molecule between the conducting electrodes is unknown, a deep understanding of the transport cannot be achieved. For this reason, knowledge of the geometry is essential. The first part of this work concerns a newly developed procedure for the controlled manipulation of single molecules, utilizing the example of 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) on the Ag(111) surface. This method is based on atomic force microscopy under ultrahigh vacuum and at low temperatures in combination with a 3D motion tracking system. Molecular self-assembly results in strong hydrogen bonds between the molecules on the surface and the new method provides an efficient way to search for the optimal trajectory for the extraction of single molecules from the molecular layer. The second part of this work builds on this method for the controlled functionalization of the scanning probe tip. A new method, scanning quantum dot microscopy (SQDM), was developed. SQDM is based on a surprisingly weak electronic coupling between the tip’s electronic bands and one or more molecular orbital(s), which exists in spite of the strong mechanical bond between the tip and the molecule. This results in the possibility to controllably modify the charge state of the tip-attached molecule by varying the bias voltage applied to the surface. SQDM made the quantitative measurement of the electrostatic potential of small surface objects possible, including the first measurement of the Smoluchowski dipole of a single silver atom on Ag(111). The first truly quantitative measurement of the work function change of Ag(111) after PTCDA adsorption with a scanning probe microscope was made possible with SQDM, where a value of (145±10) meV was obtained. A theoretical model of the experimental system was constructed, based on the orthodox theory of the Coulomb blockade. Unexpected discrepancies between theory and experiment were discovered, which contradicted the constant interaction model of quantum dots. These results are important for the future application of the theory on systems with similar characteristic length scales of ca. 1 nm.

Additional file 1. Newly designed EHV-1 LAMP primers sequences utilized in this study. Primer sequences and their lengths are outlined in the table.

Additional file 1. Newly designed EHV-1 LAMP primers sequences utilized in this study. Primer sequences and their lengths are outlined in the table.