Discovering new information on hepatic diseases

In our last story we talked about how animals can help to improve human health. This time we are talking about how humans could improve the health of animals, more specifically the health of horses and donkeys. Verena Zehetner from the University of Veterinary Medicine in Vienna has been studying the equine parvovirus-hepatitis (EqPV-H) with the help of Professor Jessika-Maximiliane V. Cavalleri and Dr. Anna S. Ramsauer. It is a virus that was only discovered in 2018 and is associated with Theiler’s disease, a fulminant and potentially life-threatening hepatic necrosis in equids.  

Theiler’s disease has been found in many countries and has so far been mostly associated with prior administration of equine-origin biological products such as equine plasma, tetanus and botulism antitoxins etc. Yet, there have been reported cases of Theiler’s disease in horses that were in contact with affected horses, but did not receive any equine-origin biological products. This indicates that an infectious and transmissible pathogen may be the cause of Theiler’s disease.

Equine parvovirus-hepatitis harbours a small single-stranded DNA genome and is assigned to the species Ungulate Copiparvovirus 6. It has been detected in all but one of the recently reported cases of Theiler’s disease and has therefore been linked to the onset of the disease.

“The research about the virus is still in its infancies and there are a lot of questions to be answered,” says Verena Zehetner. “We thought about the possible influence of equine parvovirus-hepatitis on other hepatic diseases apart from Theiler`s disease and designed our study project accordingly to answer that question.”

While recent findings suggest that EqPV-H is associated with Theiler’s disease, there are no studies available so far that were designed to answer the question, whether EqPV-H might also be associated with other hepatic diseases. Therefore, the objective of the study conducted by Verena Zehetner and her colleagues was to evaluate the prevalence and quantify the viral loads of EqPV-H in equine and donkey livers with various histopathologic abnormalities. EqPV-H DNA was qualitatively and quantitatively measured by real-time PCR and digital PCR, respectively. 

They were the first group so far to investigating the influence of EqPV-H on other hepatopathies beside Theiler’s disease. The EqPV-H assay was specifically designed for their research according to all published EqPV-H complete coding sequence variants from USA, China and Austria. They also performed digital PCR on their liver samples, which is not a novel method itself, but still not routinely used in veterinary research.

“The most important result is that we did not find an association between EqPV-H and other liver diseases in our study cohort as no viral DNA could be detected in 82 out of 84 liver samples with different histopathologic abnormalities. Interestingly the only two samples which tested positive for the virus originated from horses suffering from neoplastic diseases with metastases in the liver,” explains Zehetner.

Unfortunately (or fortunately) only a very small sample size was available for the screening of EqPV-H DNA, which means that many future investigations are expected on the topic. 

The current findings provide new informationfor all equine veterinarians and researchers focusing on hepatic diseases. The fact that EqPV-H seems to be specifically associated with Theiler’s disease is important to know. It is especially valuable knowledge for veterinarians who have to deal with horses suffering from clinical or subclinical liver disease to decide on the best diagnostic workup and treatment plan. “Cases with suspected neoplastic disease affecting or infiltrating the liver should be tested for the presence of EqPV-H to get a better understanding of whether there is an association between the virus infection and neoplasia,” adds Zehetner.

Photo of Verena Zehetner’s horse to
illustrate all the horses that this research could benefit.
Anna Gerlinger photography.

Solis BioDyne’s product used: HOT FIREPol® DNA polymerase

“We used products from Solis BioDyne for the real-time PCR and they fulfilled all expectations, and we did not have any problems. Therefore, we can recommend the use of these products,” says Verena Zehetner.

Zehetner, V., Cavalleri, J. V., Klang, A., Hofer, M., Preining, I., Steinborn, R., & Ramsauer, A. S. (2021). Equine Parvovirus-Hepatitis Screening in Horses and Donkeys with Histopathologic Liver Abnormalities. Viruses, 13(8), 1599.

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