Test Suggests Ubiquitous Herpesvirus Strains Play Role in Abortion

Researchers from France have determined equine herpesvirus (EHV)-2 and -5 might play a small role in equine abortion. They used a sensitive and rapid polymerase chain reaction (PCR) test--one that can identify sections of viral DNA--in their study.

EHV-1 is known to be the major herpesvirus responsible for equine abortion. The overall importance of the other EHVsin the horse industry has remained unclear. (For more on the different strains of EHV, see "Herpes by the Numbers" in the Equine Herpesvirus PDF download.)

According to Klaus Osterrieder, DVM, DVM Habilitation (German equivalent to a PhD), professor of Virology, College of Veterinary Medicine at Cornell University, "Abortion in mares, primarily due to infection with EHV-1, is common and is a major contributor to financial loss to the horse-breeding sector of the equine industry."

Stephane Pronost, head manager of the Research and Development department in the Frank Duncombe Laboratory (France) and colleagues collected tissue samples from 407 aborted fetuses, stillbirths, and premature (up to 7-day-old) foals from 225 farms in western France between October 2002 and June 2005. They extracted DNA from the lungs and placenta and used the herpesvirus PCR test to determine the contribution of each of the herpesviruses to equine abortion.

"Positive herpesvirus PCR signals were found in 67 of the 407 (15%) cases. Among these, 59 of the 67 (88.1%) positive signals were attributed to EHV-1," reported Pronost.

Of the remaining positive PCR signals, three were EHV-2 and one was EHV-5. The researchers inferred these viruses could have contributed to abortion in mares.

No herpesvirus PCR signals were obtained for EHV-3 or EHV-4 in any of the tissues.

According to Osterrieder, these results are intriguing and will certainly spark research into other herpesviruses potentially involved in equine abortion.

Since the PCR test is capable of detecting not only EHV-1, but also EHV-2 through EHV-5, it can therefore serve as a useful screening test in abortion cases, particularly for analyzing placental tissue.

In addition, this test could also be employed to obtain DNA sequences from new variants of equine herpesviruses.

The study, "Detection of equine herpesviruses in aborted foetuses by consensus PCR," was published in Veterinary Microbiology in January, 2008.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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