Detection of pseudorabies virus antibody in swine serum and oral fluid specimens using a recombinant gE glycoprotein dual-matrix indirect ELISA

Advances in molecular epidemiology and detection methods of pseudorabies virus

Pseudorabies (PR), a highly contagious disease caused by the pseudorabies virus (PRV), represents a significant threat to the global swine industry. Despite the success of developed countries in controlling the PRV epidemic through swine pseudorabies eradication programs, wild boars, as a potential source of infection, still require sustained attention and effective control measures. Concurrently, there has been considerable global attention directed towards cases of PRV infection in humans. In consideration of the aforementioned factors, this paper presents a comprehensive review of recent developments in the PRV genome, epidemiology, vaccine research, and molecular detection methods. The epidemiology section presents an analysis of the transmission routes, susceptible animal groups, and geographic distribution of PRV, as well as an examination of the trend of the epidemic in recent years. In the field of vaccine research, the current development of genetically engineered vaccines is emphasized, and the immunogenicity and safety of vaccines are discussed. Moreover, the molecular detection techniques utilized to identify PRV, including immunological methods, nucleic acid detection methods, biosensors, and so forth, are presented in a systematic manner. Finally, this paper presents a comprehensive discussion of the current status of PRV-related research and offers insights into future directions, with the aim of providing a foundation for the scientific prevention and control of PRV.

The immunogenicity of PRV ΔgE/TK/UL49.5 three-gene-deleted vaccine in mice

BACKGROUND

Pseudorabies (PR) caused by the re-emerging of pseudorabies virus (PRV) variant has outbroken among PRV vaccine immunized swine in many pig farms, which has caused serious social and economic consequences since the end of 2011. The PRV UL49.5 protein can inactivate the transporter associated with antigen processing (TAP), thereby downregulating the cell surface expression of swine leukocyte antigen class I (SLA-I) to evade host immune surveillance.

METHODS

In this study, based on the PRV ΔgE/TK strain, PRV ΔgE/TK/UL49.5 triple gene deletion strain was constructed through homologous recombination and deletion of the PRV UL49.5 gene by the Cre-LoxP system. Its growth curve and effect on SLA-I transcription level were determined. Preliminary studies were carried out on serum neutralizing antibody levels, IFN-γ and IL-4 cytokines levels in mice immunized with PRV ΔgE/TK/UL49.5, and the viral load and challenge protection in mice tissues after challenge.

RESULTS

The growth characteristics of PRV ΔgE/TK/UL49.5 strain were similar to those of PRV ΔgE/TK strain. The level of SLA-I was returned to normal after the deletion of PRV UL49.5 gene. The immunization of PRV ΔgE/TK/UL49.5 did not affect the weight gain of mice. Immunized mice could induce high levels of serum neutralization antibodies and immune cytokines, including IFN-γ and IL-4, which could provide complete protection against virulent PRV challenge. No obvious pathological damage was observed in lung, brain and trigeminal ganglion of mice immunized with PRV ΔgE/TK/UL49.5, and the tissue viral load was the lowest.

CONCLUSIONS

PRV ΔgE/TK/UL49.5 strain can induce enhanced immunogenicity and had the potential to be used as a candidate strain.

Pseudorabies Virus Glycoproteins E and B Application in Vaccine and Diagnosis Kit Development

Background: Pseudorabies virus (PRV) is a highly infectious pathogen that affects a wide range of mammals and imposes a significant economic burden on the global pig industry. The viral envelope of PRV contains several glycoproteins, including glycoprotein E (gE) and glycoprotein B (gB), which play critical roles in immune recognition, vaccine development, and diagnostic procedures. Mutations in these glycoproteins may enhance virulence, highlighting the need for updated vaccines. Method: This review examines the functions of PRV gE and gB in vaccine development and diagnostics, focusing on their roles in viral replication, immune system interaction, and pathogenicity. Additionally, we explore recent findings on the importance of gE deletion in attenuated vaccines and the potential of gB to induce immunity. Results: Glycoprotein E (gE) is crucial for the virus's axonal transport and nerve invasion, facilitating transmission to the central nervous system. Deletion of gE is a successful strategy in vaccine development, enhancing the immune response. Glycoprotein B (gB) plays a central role in viral replication and membrane fusion, aiding viral spread. Mutations in these glycoproteins may increase PRV virulence, complicating vaccine efficacy. Conclusion: With PRV glycoproteins being essential to both vaccine development and diagnostic approaches, future research should focus on enhancing these components to address emerging PRV variants. Updated vaccines and diagnostic tools are critical for combating new, more virulent strains of PRV.

The Deletion of US3 Gene of Pseudorabies Virus (PRV) ΔgE/TK Strain Induces Increased Immunogenicity in Mice

Re-emerging pseudorabies (PR) caused by pseudorabies virus (PRV) variant has been prevailing among immunized herds in China since 2011, indicating that commercially available PR vaccine strains couldn’t provide complete protection against novel, epidemic PRV variant. Before this study, a gE/TK-gene-deleted virus (PRV ΔgE/TK) was constructed from PRV QYY2012 variant through homologous recombination and Cre/LoxP system. Here, PRV ΔgE/TK/US3 strain was generated by deleting US3 gene based on PRV ΔgE/TK strain using the same method. The growth characteristics of PRV ΔgE/TK/US3 were analogous to that of PRV ΔgE/TK. Moreover, the deletion of US3 gene could promote apoptosis, upregulate the level of swine leukocyte antigen class I molecule (SLA-I) in vitro, and relieve inflammatory response in inoculated BALB/c mice. Subsequently, the safety and immunogenicity of PRV ΔgE/TK/US3 was evaluated as a vaccine candidate in mice. The results revealed that PRV ΔgE/TK/US3 was safe for mice, and mice vaccinated with PRV ΔgE/TK/US3 could induce a higher level of PRV-specific neutralizing antibodies and cytokines, including IFN-γ, IL-2 and IL-4, also higher level of CD8+ CD69+ Tissue-Resident Memory T cells (TRM). The results show that the deletion of US3 gene of PRV ΔgE/TK strain could induce increased immunogenicity, indicating that the PRV ΔgE/TK/US3 strain is a promising vaccine candidate for preventing and controlling of the epidemic PR in China.