Viruses in Horses with Neurologic and Respiratory Diseases

Abstract

Metagenomics was used to identify viral sequences in the plasma and CSF (cerobrospinal fluid) of 13 horses with unexplained neurological signs and in the plasma and respiratory swabs of 14 horses with unexplained respiratory signs. Equine hepacivirus and two copiparvoviruses (horse parvovirus-CSF and a novel parvovirus) were detected in plasma from neurological cases. Plasma from horses with respiratory signs contained the same two copiparvoviruses plus equine pegivirus D and respiratory swabs contained equine herpes virus 2 and 5. Based on genetic distances the novel copiparvovirus qualified as a member of a new parvovirus species we named Eqcopivirus. These samples plus another 41 plasma samples from healthy horses were tested by real-time PCRs for multiple equine parvoviruses and hepacivirus. Over half the samples tested were positive for one to three viruses with eqcopivirus DNA detected in 20.5%, equine hepacivirus RNA and equine parvovirus-H DNA in 16% each, and horse parvovirus-CSF DNA in 12% of horses. Comparing viral prevalence in plasma none of the now three genetically characterized equine parvoviruses (all in the copiparvovirus genus) was significantly associated with neurological and respiratory signs in this limited sampling.

Tropism, pathology, and transmission of equine parvovirus-hepatitis

“…Horse A, which had clinical signs of liver failure, had the most severe histopathologic changes at the onset of hepatitis (Figure 4(D)). Inflammatory infiltrates and hepatocellular necrosis had a primarily centrilobular distribution, as has been described for Theiler's disease [2,6]. Evidence of resolution and recovery was already evident 7 days later (Figure 4(E)).…”

“…Equine parvovirus-hepatitis (EqPV-H) was first described in 2018 in a case of Theiler's disease, a form of acute hepatic necrosis [1]. In the United States, China, and Germany, EqPV-H has an estimated viremia prevalence of 2.9-17%, with 54% prevalence on farms where Theiler's disease was recently documented [1][2][3][4][5][6]. EqPV-H infection is closely linked to both Theiler's disease and subclinical hepatitis [2,7].…”

Viral Equine Encephalitis, a Growing Threat to the Horse Population in Europe?

“…Bearing in mind that three flaviviruses responsible for equine encephalitis are described in Europe, and that serological cross-reactivity is frequently observed in flavivirus indirect diagnosis assays, the development of multiplex approaches that allow the comparison of serological reactions against a wide range of pathogens appear to be valuable options [184,185]. Furthermore, because in about one-half of infectious equine encephalitis, no known pathogen can be evidenced [4], identification of unknown neuropathogenic viruses by classical (electron microscopy) and more recent high-throughput techniques (next generation sequencing for example) is highly desirable [186,187]. In these two recent studies, three viruses, Shuni virus, horse parvovirus-CSF and eqcopivirus, have been identified as potential causes of neurologic disease in horses through unbiased detection from different tissues or body fluids; the demonstration of infectious virus from the brain of sick horses establish Shuni virus as a novel equine neuropathogenic virus [186], while for the other two viruses for which genomic DNA was detected in CSF and/or plasma [187], comparison of virus prevalence in the CSF of healthy horses (case-control study) would be required before a conclusion on the aetiology of equine encephalitis can be reached.…”

Special Issue “Equine Viruses”: Old “Friends” and New Foes?

“…Altan et al [9] have used metagenomics to identify viruses in horses with neurological and respiratory diseases. The equine hepacivirus (EqHV) was detected in the plasma from several neurological cases.…”

“…This virus, which was first reported in horses in 2012 [10], was further investigated by Badenhorst et al [11], with a specific focus on its circulation in Austria and the potential role of mosquitoes in its transmission. Altan et al [9] also detected two copiparvoviruses, the equine parvovirus-hepatitis (EqPV-H) and a new one named Eqcopivirus by the authors, with no specific and/or statistical association with disease. No EqHV RNA was found in mosquitoes collected across Austria, raising questions about its methods of transmission.…”