31 January 2017

HEALTH - Two New Canine Flu Vaccines Developed

It’s flu season and not just for humans - dogs get the flu too.

To combat canine influenza, scientists at University of Rochester School of Medicine and Dentistry have developed the two new vaccines.

Currently veterinarians use vaccines that include inactivated or killed flu virus, but experts say they provide short-term, limited protection.

The new vaccines are “live-attenuated”  and work against H3N8 canine influenza virus, which is currently circulating in dogs in the US, along with the H3N2 virus.

Past research shows that live-attenuated vaccines, made from live flu virus that is dampened down so that it doesn’t cause the flu, provide better immune responses and longer periods of protection.

Scientists, led by Luis Martinez-Sobrido, Ph.D., used a genetic engineering technique called reserve genetics to create a live vaccine that replicates in the nose, but not in the lungs.

The nose is where the virus first enters a dog’s body, so generating an immune response there could stop the virus in its tracks.

The study found the vaccine was safe and able to induce better immune protection against H3N8 canine influenza virus in mice and dog tracheal cells than a commercially available inactivated vaccine.

To develop the second vaccine the team used reserve genetics to remove a protein called NS1 from H3N8 canine influenza virus.

Previous studies have shown that deleting the NS1 viral protein significantly weakens flu viruses so that they elicit an immune response but don’t cause illness, and this process has been successfully used for humans, horses and more.

The next step is clinical trials with dogs.

The team’s goal is to come up with new options to stem the spread of canine influenza in shelters and kennels, and to avoid the transmission of a dog flu virus to people.

According to the CDC there has been no evidence of transmission of canine influenza viruses from dogs to people and there has not been a single reported case of human infection with a canine influenza virus.

“However, influenza viruses are constantly changing and it is possible for a virus to change so that it could infect humans and spread easily between humans.”

This potential was recently illustrated when a veterinarian contracted avian flu (H7N2) through contact with a cat - the first time cats had gotten avian flu and first time it was passed to a human via a feline.  

By preventing dogs from getting the flu in the first place, the risk to humans in negated.

Canine influenza H3N8 virus originated in horses and has been known to exist in horses for more than 40 years.

The first canine infections were discovered in 2004 in greyhounds.

Symptoms include cough, runny nose and fever, but not all dogs will show signs of illness.

The severity of illness associated with canine flu in dogs can range from no signs to severe illness resulting in pneumonia and sometimes death.

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