Two new vaccines developed for canine flu

Published: 31-Jan-2017

Scientists have developed live-attenuated vaccines to help prevent canine influenza virus from jumping to humans


Dogs that have been infected with multiple influenza viruses have the potential to act as "mixing vessels" and generate new flu strains that could infect people.

Two influenza A virus subtypes have been reported in dogs in the last 16 years – the canine influenza virus (CIV) H3N8 and H3N2 of equine and avian origin, respectively.

To date, only inactivated influenza vaccines (IIVs) are available to prevent CIV infections but experts say they provide short-term, limited protection.

Scientists from the University of Rochester School of Medicine and Dentistry have developed vaccines instead using live-attenuated CIV vaccines (LACIVs).

Live-attenuated vaccines reduce the virulence of a pathogen but keep it viable. Past research shows that live-attenuated vaccines provide better immune responses and longer periods of protection.

Led by Luis Martinez-Sobrido, Associate Professor in the department of Microbiology and Immunology, the team created two LACIVs against H3N8, which is currently circulating in dogs in the US.

The team used reserve genetics to create a live vaccine that replicates in the nose, where a virus first enters a canine's body. Generating an immune response in the nasal passages could stop the virus sooner and more effectively. A vaccine inside the lungs could create inflammation in response to the live virus.

The team found that H3N8 LACIV replicates efficiently in canine cells at 33oC but is impaired at 37-39oC temperatures.

In a second study, the team used the same technique to remove protein NS1 from H3N8. Previous studies showed that deleting the NS1 viral protein significantly weakens flu viruses so that they elicit an immune response but do not cause illness.

This approach has been used with human, swine and equine flu viruses to generate potential vaccines.

Both studies found that the live vaccine was better able to induce immune protection against H3N8 in mice and dog tracheal cells than a commercially available IIV. The study was published in the Journal of Virology.

The team is planning to test both live-attenuated vaccines in clinical trials. The hope is to come up with new options to restrict the spread of flu in shelters and kennels.

As many people are in close contact with dogs on a regular basis, Martinez-Sobrido believes it is advisable to prevent dogs from catching the influenza to avoid it spreading to humans.

The team is using this research to tackle other CIV – including H3N2 introduced in the US in 2015.

Early results show that similar to the H3N8 vaccine, the H3N2 LACIV is more effective than the only currently available IIV.

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