Marine compound shows promise in fight against EHV-1

Virologist Art Framptom. Photo: University of North Carolina Wilmington
Virologist Art Framptom. © University of North Carolina Wilmington

Researchers are investigating a compound derived from micro-algae as a potential agent in the fight against Equine Herpes Virus-1 (EHV-1).

EHV-1 is an economically damaging and highly contagious disease that can cause symptoms that include fever, depression, watery nose, and loss of appetite. The disease can also trigger abortion in mares and its neurological form, which appears to have been on the rise in the US in recent years, can prove deadly.

Most horses are exposed to the virus at a young age and it remains with them for life. However, it can emerge as a serious illness later in life, particularly during times of stress.

Now, scientists at the University of North Carolina Wilmington hold out hopes for developing an anti-viral drug, with research centering on a promising compound extracted from a form of marine micro-algae.

University virologist Art Frampton is taking a two-pronged approach: providing appropriate surveillance measures to detect an outbreak and, if EHV-1 is confirmed, administer an anti-viral drug to limit its spread.

It is hoped that an anti-viral medication developed from the micro-algae could target the infection in the respiratory tract, preventing it from entering the blood stream and causing more serious health issues.

Frampton and his colleagues focused on compounds derived from marine micro-algae and cyanobacteria, which were isolated and purified by chemists at the university’s Center for Marine Science.

This collection contains thousands of compounds isolated from photosynthetic and non-photosynthetic marine organisms.

“What we have here is a library of organisms that have never been examined by anybody in detail in terms of chemical constituents and their biological properties,” says Professor Carl Brown, a bio-organic chemist.

Frampton received 480 chemical fractions that he and his undergraduate students tested for their potential effectiveness in blocking the life cycle of EHV-1.

Of these, one was found to be best because it blocked virus replication while remaining non-toxic to the cell.
Frampton and his students are continuing to study the compound on a basic cellular level to determine precisely how it blocks the virus.

The compound is produced by a photosynthetic dinoflagellate, a micro-algae found in the ocean.

“If we can generate drug-resistant viruses, we might be able to go in and sequence those and see where the mutations in the virus are occurring. That might clue us into where and how the drug is acting,” Frampton says.

If the algae-based compound works, it could stop EHV-1 from spreading past the respiratory tract into an infected horse’s neurological or reproductive system, where it can do much more damage.

Frampton’s research is currently funded by the Grayson-Jockey Club Research Foundation. He is seeking further funding to expand his EHV-1 study into the realm of cancer research.

In research to date, Frampton and graduate student Lauren Singletary have identified a novel receptor, MHC class I (MHCI) – a portion of a horse cell that the virus uses as an entrance. Found in human and animal cells, MHCI normally aids the immune response system. When EHV-1 enters a horse cell via MHCI, it is able to replicate, spread and cause disease.

Clinical signs of infection, such as fever, coughing, nasal discharge and neurological disease can show up within 24 hours after virus entry, but typically the incubation period is four to six days.

In addition to identifying which receptor the virus uses to enter the cell, Singletary and Frampton are working to determine which viral molecules attach to the receptor to permit virus entry.

Singletary says: “The virus particles of EHV-1 contain 13 different glycoproteins on the surface. These are special sugar-protein molecules that specifically interact with receptors to allow entry into the cell.

“I am trying to figure out which glycoproteins are binding to our receptor. Once I can determine that, I want to go further to find out specifically which part of the protein is binding to which part of the receptor.”

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