Highly contagious fowl cholera is a problem in all poultry-producing countries, particularly where the birds are intensively reared, and also due to organic and free-range practices. Treatment is very difficult due to the fast progression of the disease and so vaccination of layers and breeders, is considered a better option.
Professor Ben Adler, Director of the ARC Centre of Excellence in Structural and Functional Microbial Genomics, led the research team which developed the bacteria forming the basis of the vaccine in the mid-1990s. Bioproperties Pty Ltd then extensively tested and commercialised the vaccine which is being marketed as Vaxsafe PM.
“It was fantastic to have the vaccine developed by an Australian company,” Professor Adler said.
“This vaccine is likely to be safer and more effective than the live fowl cholera vaccines which are used overseas.
“It’s a live vaccine, so it stimulates a better immune response than a vaccine based on killed, or inactivated bacteria. It’s effective against a number of strains of fowl cholera, providing broad-based protection, rather than being effective against just one strain, like killed vaccines,” Professor Adler said.
Live vaccines are derived from the microbe against which they ultimately protect. Vaxsafe PM simulates an infection, but the bacteria have been attenuated in the laboratory, meaning they are unable to proliferate to the point of causing illness. However, the body’s immune system still responds and produces antibodies against the infection.
“This live vaccine is safer than others used overseas because we understand the basis on which it is attenuated. Previously, scientists were able to attenuate the bacteria, but the technology didn’t exist to identify the exact mechanism. As a result, they couldn’t entirely predict how the vaccine strain would work in the field and sometimes vaccine-associated disease outbreaks actually occurred,” Professor Adler said.
“With Vaxsafe PM, we know the precise mechanism by which the bacteria have been attenuated, thus overcoming this problem.”
Professor Adler and his team continue to research fowl cholera, investigating how the bacteria cause disease at the molecular level. A project lead by Dr John Boyce and Dr Marina Harper within the ARC Centre is also working with the Australian Poultry Cooperative Research Centre to develop a better diagnostic test for the disease.