CRISPR/Cas9-based generation of a recombinant double-reporter pseudorabies virus and its characterization in vitro and in vivo

Genome editing of pseudorabies virus in the CRISPR/Cas9 era: a mini-review

Pseudorabies virus (PRV) is an important swine virus that has a significant impact on the global swine industry. PRV is a member of the herpesvirus family, specifically the alphaherpesvirus subfamily, and has been extensively utilized as a prototype herpesvirus. Notably, recent studies have reported that PRV sporadically spills over into humans. The PRV genome is approximately 150 kb in size and is difficult to manipulate at the genomic level. The development of clustered regularly interspaced short palindromic repeat-associated protein (CRISPR/Cas9) technology has revolutionized PRV genome editing. CRISPR/Cas9 has been widely used in the construction of reporter viruses, knock-out/knock-in of genes of interest, single virus tracking and antiviral strategies. Most importantly, for vaccine development, virulence gene knockout PRV vaccine candidates can be obtained within 2 weeks using CRISPR/Cas9. In this mini-review, we provide a concise overview of the application of CRISPR/Cas9 in PRV research and mainly share our experience with methods for efficiently editing the PRV genome. Through this review, we hope to give researchers better insight into the genome editing of pseudorabies virus.

Recombinant Pseudorabies Virus Usage in Vaccine Development against Swine Infectious Disease

Pseudorabies virus (PRV) is the pathogen of pseudorabies (PR), which belongs to the alpha herpesvirus subfamily with a double stranded DNA genome encoding approximately 70 proteins. PRV has many non-essential regions for replication, has a strong capacity to accommodate foreign genes, and more areas for genetic modification. PRV is an ideal vaccine vector, and multivalent live virus-vectored vaccines can be developed using the gene-deleted PRV. The immune system continues to be stimulated by the gene-deleted PRVs and maintain a long immunity lasting more than 4 months. Here, we provide a brief overview of the biology of PRV, recombinant PRV construction methodology, the technology platform for efficiently constructing recombinant PRV, and the applications of recombinant PRV in vaccine development. This review summarizes the latest information on PRV usage in vaccine development against swine infectious diseases, and it offers novel perspectives for advancing preventive medicine through vaccinology.

Inhibition of USP14 influences alphaherpesvirus proliferation by degrading viral VP16 protein via ER stress-triggered selective autophagy

Alphaherpesvirus infection results in severe health consequences in a wide range of hosts. USPs are the largest subfamily of deubiquitinating enzymes that play critical roles in immunity and other cellular functions. To investigate the role of USPs in alphaherpesvirus replication, we assessed 13 USP inhibitors for PRV replication. Our data showed that all the tested compounds inhibited PRV replication, with the USP14 inhibitor b-AP15 exhibiting the most dramatic effect. Ablation of USP14 also influenced PRV replication, whereas replenishment of USP14 in USP14 null cells restored viral replication. Although inhibition of USP14 induced the K63-linked ubiquitination of PRV VP16 protein, its degradation was not dependent on the proteasome. USP14 directly bound to ubiquitin chains on VP16 through its UBL domain during the early stage of viral infection. Moreover, USP14 inactivation stimulated EIF2AK3/PERK- and ERN1/IRE1-mediated signaling pathways, which were responsible for VP16 degradation through SQSTM1/p62-mediated selective macroautophagy/autophagy. Ectopic expression of non-ubiquitinated VP16 fully rescued PRV replication. Challenge of mice with b-AP15 activated ER stress and autophagy and inhibited PRV infection in vivo. Our results suggested that USP14 was a potential therapeutic target to treat alphaherpesvirus-induced infectious diseases.