Z/2011, which was isolated in China. Our results demonstrate that this recombinant strain is safe and provides effective protection in young chickens against QX-like IBV challenge.

2  Materials and methods

2.1  Vaccine and viruses
The H120 vaccine strain is currently a widely used vaccine strain, created from 120 serial passages of the H strain isolated in 1956. The ck/CH/IBYZ/2011 strain (referred to as IBYZ, GenBank KF663561.1) u