Equine parvovirus-hepatitis (EqPV-H) has recently been associated with cases of Theiler's disease, a form of fulminant hepatic necrosis in horses. To assess whether EqPV-H is the cause of Theiler's disease, we first demonstrated hepatotropism by PCR on tissues from acutely infected horses. We then experimentally inoculated horses with EqPV-H and 8 of 10 horses developed hepatitis. One horse showed clinical signs of liver failure. The onset of hepatitis was temporally associated with seroconversion and a decline in viremia. Liver histology and in situ hybridization showed lymphocytic infiltrates and necrotic EqPV-H-infected hepatocytes. We next investigated potential modes of transmission. Iatrogenic transmission via allogeneic stem cell therapy for orthopedic injuries was previously suggested in a case series of Theiler's disease, and was demonstrated here for the first time. Vertical transmission and mechanical vectoring by horse fly bites could not be demonstrated in this study, potentially due to limited sample size. We found EqPV-H shedding in oral and nasal secretions, and in feces. Importantly, we could demonstrate EqPV-H transmission via oral inoculation with viremic serum. Together, our findings provide additional information that EqPV-H is the likely cause of Theiler's disease and that transmission of EqPV-H occurs via both iatrogenic and natural routes.
The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced owing to emerging variants of concern
Electric cell-substrate impedance sensing (ECIS) measures changes in an electrical circuit formed in a culture dish. As cells grow over a gold electrode, they block the flow of electricity and this is read as an increase in electrical impedance in the circuit. ECIS has previously been used in a variety of applications to study cell growth, migration, and behavior in response to stimuli in real time and without the need for cellular labels. Here, we demonstrate that ECIS is also a valuable tool with which to study infection by alphaherpesviruses. To this end, we used ECIS to study the kinetics of cells infected with felid herpesvirus type 1 (FHV-1), a close relative of the human alphaherpesviruses herpes simplex virus 1 (HSV-1) and HSV-2, and compared the results to those obtained with conventional infectivity assays. First, we demonstrated that ECIS can easily distinguish between wells of cells infected with different amounts of FHV-1 and provides information about the cellular response to infection. Second, we found ECIS useful in identifying differences between the replication kinetics of recombinant DsRed Express2-labeled FHV-1, created via CRISPR/Cas9 genome engineering, and wild-type FHV-1. Finally, we demonstrated that ECIS can accurately determine the half-maximal effective concentration of antivirals. Collectively, our data show that ECIS, in conjunction with current methodologies, is a powerful tool that can be used to monitor viral growth and study the cellular response to alphaherpesvirus infection. IMPORTANCE Alphaherpesviruses, including those that commonly infect humans, such as HSV-1 and HSV-2, typically infect and cause cellular damage to epithelial cells at mucosal surfaces, leading to disease. The development of novel technologies to study the cellular responses to infection may allow a more complete understanding of virus replication and the creation of novel antiviral therapies. This study demonstrates the use of ECIS to study various aspects of herpesvirus biology, with a specific focus on changes in cellular morphology as a result of infection. We conclude that ECIS represents a valuable new tool with which to study alphaherpesvirus infections in real time and in an objective and reproducible manner.
Abstract Background Theiler’s disease, a.k.a. equine serum hepatitis, is a devastating, highly fatal disease of horses. Equine parvovirus-hepatitis (EqPV-H) has been identified as the likely cause of this disease. While the incidence of Theiler’s disease is low, the prevalence of EqPV-H DNA in horses is high, with up to 37% in some regions, suggesting that subclinical or persistent infection is common. Methods To determine the prevalence and pathogenicity of EqPV-H infection at New York racetracks, DNA was extracted from archived formalin-fixed, paraffin-embedded liver tissues from racehorses submitted for necropsy to the Animal Health Diagnostic Center as part of the New York State Gaming Commission-Cornell University postmortem examination program. A total of 191 liver samples from horses between 2 and 13 years old were evaluated. Extracted DNA was tested for EqPV-H using PCR and gel electrophoresis. PCR-positive samples were further assessed for tissue morphology using histology and detection of viral nucleic acid using in situ hybridization. Results Forty-two samples were PCR positive (22%). Of those, 31 samples had positive viral nucleic acid hybridization in hepatocytes with 11 samples showing positive hybridization in necrotic hepatocytes associated with inflammatory cells, indicating active hepatitis. Both individual hepatocyte necrosis and hepatitis were positively associated with EqPV-H detection (p < 0.0001 and p = 0.0005, respectively). Conclusion These findings indicate that presence of EqPV-H in the liver and parvoviral-associated hepatitis are prevalent in racehorses from New York racetracks, thus warranting additional studies examining potential associations between EqPV-H infection and racehorse performance.
Stem-cell therapy represents a promising strategy for the treatment of challenging pathologies, such as large, infected wounds that are unresponsive to conventional therapies. The present study describes the clinical application of peripheral blood stem cells (PBSCs) for the treatment of four adult Warmblood horses with naturally occurring wounds, which were unresponsive to conventional therapies for at least 3 months. A visual assessment was performed, and a number of wound-healing parameters (granulation tissue, crust formation and scar formation) were evaluated. In all cases, tissue overgrowth was visible within 4 weeks after PBSC injection, followed by the formation of crusts and small scars in the centre of the wound, with hair regeneration at the edges. In conclusion, this is the first report of PBSC therapy of skin wounds in horses, and it produced a positive visual and clinical outcome.
