Abstract: Disclosed is a molecular marker for genetic resistance of chicken to infection by subgroups A and K avian leukosis virus (ALV-A and ALV-K) and use thereof the molecular marker is tva gene with base deletion between 318-323 and/or between 602-607; specifically, bases ACCTCC at positions 318-323 and bases CCGCTG at positions 602-607 are deleted. In the present disclosure, genetic variation of tva receptor gene in Chinese chicken breeds is analyzed, and it is found that the DNA sequence of tva receptor gene in the Chinese chicken breeds has base deletion at positions 318-323 or at positions 602-607. Moreover, a method for breeding of the chicken breeds resistance to ALV-A and ALV-K has been established.

Abstract: The present disclosure provides a method for rapid preparation of an epidemic infectious bronchitis vaccine. An infectious clone of an infectious bronchitis virus (IBV) H120 vaccine strain is used as a skeleton carrier and an antigen gene in the skeleton carrier is replaced with a target antigen gene of an epidemic infectious bronchitis virus strain, to obtain a recombinant bronchitis virus. The target antigen gene is an S1 gene or an S gene. The S gene is one of the S gene fragments of the epidemic infectious bronchitis virus strain or a fusion gene composed of multiple S gene fragments. Furthermore, the target antigen gene and an N gene can be simultaneously replaced and a signal peptide region of the original S1 gene in the skeleton carrier is retained during the replacement.