A recently discovered virus linked to liver disease in horses appears to have worldwide distribution, according to researchers, who tested pooled commercial serum samples for DNA from the pathogen.
The study team said they found DNA from equine parvovirus-hepatitis (EqPV-H) in more than half the commercial horse serum samples tested. They said they could not determine if these DNA particles were infectious.
The scientists said that sensitive tests should be used for the detection of EqPV-H DNA in serum, and a careful risk assessment should be performed when using commercial horse sera in medical and research applications.
EqPV-H was only recently identified in association with equine serum hepatitis, also known as Theiler’s disease.
This disease was first described by Arnold Theiler in 1918 and is often observed after the use of blood products in equines.
The disease has since been reported worldwide after treatment with a variety of equine serum products, for instance, tetanus antitoxin, botulinum antitoxin, antiserum against Streptococcus equi, as well as pregnant mare’s serum, and equine plasma.
Until now, the virus has been described only in the United States and China.
In their study, Toni Luise Meister and her colleagues in Germany and Austria set out to evaluate the presence of EqPV-H in 18 commercial serum samples to assess the potential risk of virus transmission.
In 11 out of the 18 commercial serum samples tested, EqPV-H DNA was detected. Further testing revealed the presence of antibodies against the EqPV-H VP1 protein in all of the samples in which DNA was found, as well as three additional samples in which none of the viral DNA was found.
“The countries of origin with detectable viral genomes included the United States, Canada, New Zealand, Italy, and Germany, suggesting a worldwide distribution of EqPV-H,” the researchers reported in the journal Viruses.
They suggested it was highly likely that parvovirus DNA was enclosed in viral particles in the serum samples that tested positive for DNA.
In conclusion, the authors said: “We showed that anti-EqPV-H DNA and EqPV-H antibodies are frequently detectable in commercially available horse sera from various origins indicating a worldwide circulation of EqPV-H infections.
“As horse sera are commonly used for production of anti-sera, which are licensed for various treatments in different animal species as well as humans (snake antivenom immunoglobulins and botulism antitoxin), these results should raise awareness for EqPV-H contamination.
“Furthermore, other biologicals like live vaccines might harbor infectious EqPV-H, for instance when cell lines used for virus propagation were cultivated with horse serum.”
This, they said, pointed to the need to use sensitive diagnostic tests for the detection of EqPV-H DNA, as well as a careful risk assessment when using commercial horse sera in medical and research applications.
Equine Parvovirus-Hepatitis Frequently Detectable in Commercial Equine Serum Pools
Toni Luise Meister, Birthe Tegtmeyer, Alexander Postel, Jessika-M.V. Cavalleri, Daniel Todt, Alexander Stang and Eike Steinmann.
Viruses 2019, 11(5), 461; https://doi.org/10.3390/v11050461