The present invention discloses a type II Pseudorabies virus attenuated strain and its preparation method and application. The attenuated strain of pseudorabies virus is gE/TK-double-deficient strain, which is named as PRV-HD/c strain of PRV dual-deletion strain, and the accession number is CGMCC No. 14325. The attenuated strain of the pseudorabies virus of the present invention is obtained from the newly isolated strain of pseudorabies virus type II after deletion of the gE and TK double genes and has reduced pathogenicity and strong immunogenicity and is inactivated by the attenuated strain of pseudorabies virus vaccines or live attenuated vaccines, which can provide effective immunity to PRV susceptible animals such as pigs and mice.

The present invention is directed to a mutated recombinant herpesvirus, e.g., varicella zoster virus (VZV) and simian varicella virus strains or HSV-1 or HSV-2 strains, vaccines containing, and methods for the construction and use thereof to elicit protective immunity in susceptible individuals, wherein the particular herpesvirus is modified to render the virus replication deficient, i.e., the virus substantially or only replicates under defined conditions, by the incorporation of at least one destabilization domain in or fused to a gene essential for herpesvirus replication. The invention particularly relates to the use of the resultant conditionally replication defective herpesviruses, e.g., a mutated VZV strains in vaccine compositions in order to immunize individuals against herpesvirus infection, e.g., in the case of VZV chickenpox and to protect against shingles and zoster, or to prevent the reactivation of VZV or other herpesvirus reactivation and the onset of shingles or another condition relating to the reactivation of another herpesvirus infection, e.g., as a consequence of advanced age, stress, inflammation, drug or other therapy, cancer, or immunodeficiency such as in HIV-AIDS or other diseases resulting in impaired T and/or B cell immunity.

The present invention discloses a type II Pseudorabies virus attenuated strain and its preparation method and application. The attenuated strain of pseudorabies virus is gE/TK-double-deficient strain, which is named as PRV-HD/c strain of PRV dual-deletion strain, and the accession number is CGMCC No. 14325. The attenuated strain of the pseudorabies virus of the present invention is obtained from the newly isolated strain of pseudorabies virus type II after deletion of the gE and TK double genes and has reduced pathogenicity and strong immunogenicity and is inactivated by the attenuated strain of pseudorabies virus vaccines or live attenuated vaccines, which can provide effective immunity to PRV susceptible animals such as pigs and mice.

The present invention provides an attenuated strain of porcine pseudorabies virus (PRV), in which said attenuated strain of PRV is a variant strain of PRV with inactivation of gI/gE/11K/28K proteins. In addition, the present invention also provides a vaccine composition comprising the attenuated strain of PRV as an antigen, a preparation method and use thereof. Proved by immunogenicity and pathogenicity testing of the live vaccine, said live PRV vaccine can provide a good protection for pigs with no clinical signs observed, indicating excellent immune protection.

Methods of producing a pathogen with reduced replicative fitness are disclosed, as are attenuated pathogens produced using the methods. In particular examples, the method includes deoptimizing one or more codons in a coding sequence, thereby reducing the replicative fitness of the pathogen. Methods of using the attenuated pathogens as immunogenic compositions are also disclosed.

Methods of producing a pathogen with reduced replicative fitness are disclosed, as are attenuated pathogens produced using the methods. In particular examples, the method includes deoptimizing one or more codons in a coding sequence, thereby reducing the replicative fitness of the pathogen. Methods of using the attenuated pathogens as immunogenic compositions are also disclosed.

The present invention provides compositions or vaccines that contain a recombinant EHV-1 that elicit an immune response in animals against equine herpesvirus, including compositions comprising the recombinant EHV-1, methods of vaccination against equine herpesvirus, and kits for use with such methods and compositions.