Vaccines for mutated chickens become new strains

A new study shows two different vaccines, used simultaneously to control an acute respiratory disease in chickens, combined to create new strains of infectious viruses.

These vaccines have been used to control infectious tracheal inflammation (ILT), according to Top News. ILT can account for 20% of mortality in some flocks and has a significant economic impact in the poultry industry.

Combination vaccines turn into new strains

Researchers at the University of Melbourne (Australia) found that, when two different strains of ILT were used in the same population, they combined into two new strains (a process called recombination), leading to disease outbreaks. Neither ILT nor the new strain is transmitted to humans or other animals, and does not threaten food safety.

The research leader, Professor Joanne Devlin, said the previous combination of vaccine strains outside the laboratory is thought to be very unlikely, but the study shows that this is possible and has resulting in outbreaks of disease in poultry.

It is known that ILT is a "live attenuated vaccine" , meaning that the virus has some pathogens removed but the immune system still recognizes the virus to fight a true infection.

"Live vaccines are used all over the world to control ILT in poultry. Over the past 40 years, Australian vaccines have been taken from a virus strain in the country. However, after a shortage of vaccines another vaccine of European origin was registered in 2006 and quickly used widely , "said Devlin.

'Immediately after the introduction of the European vaccine strain, two newly discovered ILT strains caused most of the epidemics in New South Wales and Victoria. So we had to find a way to test the origin of these two new strains , 'added Joanne Devlin.

Research results have been published in the latest issue of Science.