Antibody infusions seen as a way to fight infectious equine anemia in horses

photo by Kayla Farmer

Modeling by scientists suggests that the virus that causes equine infectious anemia could be eliminated from horses through repeated vaccination with antibodies.

Equine infectious anemia virus (EIAV) primarily infects horses. It shares many characteristics with HIV in humans, including its viral structure, genome, life cycle, and blood transmission.

The virus establishes a persistent infection and is transmitted between horses by biting flies. There is currently no vaccine or treatment, and infected horses enter a lifelong carrier state if they survive the acute phase of infection.

The disease is widespread around the world, with many jurisdictions requiring the euthanasia of infected horses.

Researchers Elissa Schwartz, Christian Costris-Vas and Stacey Smith described the infection as a major concern for equine health worldwide, being one of 11 equine infections requiring notification to the World Organization for Animal Health.

Recent outbreaks have been reported in North America, South America, Asia and throughout Europe.

Genetically diverse strains of the virus have been found. The infection usually has three stages: an acute stage characterized by high fever and low platelet count; a chronic stage with high viral loads, recurring fevers and weight loss; and a symptom-free phase with a reduced viral load and an absence of apparent clinical signs.

“One of the reasons these viruses are difficult to control is that the mutation allows them to evade therapy and immune responses,” the trio said. “We need to better understand how antibodies can control EIAV infection when the virus mutates.”

The study team, writing in the diary Virus, this research has shown that protection against the virus can be achieved in horses with severe combined immunodeficiency (SCID) by three infusions of treated plasma from long-term immunocompetent horses infected with the virus.

They noted that vaccination of horses by infusion of EIAV-specific antibodies containing plasma is not a treatment in development. In fact, work on plasma infusion in SCID horses has been undertaken to better understand the development of vaccines against HIV infection in humans.

The potential of antibody infusions to control EIAV holds great promise for the potential elimination of other lentiviruses, such as HIV, they said. However, the utility of this approach is limited by the escape potential of the mutants.

The study team applied mathematical modeling, taking into account the current mutation and the relationship between growth and antibody control, to determine whether multiple infusions had the potential to completely clear the virus in patients. horses.

Work has shown that seven infusions of an antibody vaccine, provided they are properly timed, are sufficient to eradicate both wild-type and mutant strains of the virus in a horse.

“This suggests a way forward for viral control not only of EIAV but for other viral infections in which escape by mutants resistant to neutralization is a concern,” they said.

Schwartz is at Washington State University; Costris-Vas and Stacey Smith are at the University of Ottawa.

Schwartz, EJ; Costris-Vas, C .; Smith ?, SR Modeling of the mutation in equine infectious anemia virus infection suggests a pathway to viral clearance with repeated vaccination. Virus 2021, 13, 2450. https://doi.org/10.3390/v1312245

The study, published under a Creative Commons license, can be read here.

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