International Journal of Molecular Veterinary Research, 2025, Vol.15, No.1, 32-42 http://animalscipublisher.com/index.php/ijmvr 39 to enable reproducibility and comparability of diagnostic results across regions and surveillance networks (Zhao et al., 2024). 7.3 Impact of viral high variability on vaccines and diagnostic assays PRRSV is also characterized by a highly elevated mutation rate and a high rate of recombination, which favors a high level of genetic and antigenic diversity. Not only does this render the generation of widely protective vaccines challenging but also poses serious challenges for the construction of diagnostic tests. Primer- or probe-binding site mutations may render PCR-based tests insensitive and non-specific to give false-negative results. Similarly, antigenic drift and recombination can decrease the effectiveness of vaccines and alter patterns of immune recognition (Guo et al., 2018). Continuous genomic surveillance and regular updating of diagnostic reagents are therefore critical to the maintenance of detection reliability and successful immunization coverage. 7.4 Disconnection between basic research and clinical control practices There remains a long-standing gap between differing basic molecular studies and translating them into viable disease control interventions. Although a vast majority of studies have identified key molecular determinants of virulence, immune evasion, and host response, these remain partially integrated in vaccine construction, field diagnostics, or biosecurity interventions. Most importantly, laboratory assays are conducted under conditions of control, which may not necessarily reflect the complexity of field infections, co-infections, and control factors. Strengthening the coordination between research institutions, diagnostic laboratories, and the swine production industry is imperative to close this gap. Translational research that uncovers molecular results with field application in disease management will be essential to improve the prevention, diagnosis, and control of PRRSV (Zheng et al., 2023). 8 Concluding Remarks Over the past three decades, tremendous progress has been achieved toward deciphering the molecular and biological characteristics of PRRSV. The genomics of viruses have explained the genomic organization of the PRRSV, functions of structural and nonstructural proteins, and their functions in viral replication and immune evasion. Experiments confirmed that PRRSV employs unique mechanisms-modulation of interferon signaling, inhibition of the host antiviral response, and disruption of cytokine production-to establish persistent infection. Identification of critical cellular receptors like CD163 and Siglec-1 has also paved the way for viral entry and tropism. Molecular diagnostic assays have kept up as well. Detailed and reliable PRRSV detection is now possible with the help of quantitative RT-PCR, RT-LAMP, and digital PCR, and next-generation sequencing has revolutionized the identification of novel variants and recombinants. The convergence of bioinformatics and molecular epidemiology has significantly improved viral evolution monitoring, pattern of transmission, and distribution of genotypes worldwide. Although there is immense success, diagnostic speed and accuracy remain most difficult in PRRSV control. High mutation frequency and recurrent recombination activities of the virus are prone to lead to failure or false negatives by using traditional assays. Multiplex and high-throughput platforms that can discriminate among PRRSV genotypes, variants, and co-infections are therefore needed to be developed. Advances in point-of-care testing (POCT), microfluidic chips, and transportable nucleic acid amplification platforms have made possible in-field, real-time diagnosis of PRRSV outbreaks. Standardized and validated diagnostic protocols will be necessary to ensure comparable data between laboratories and between the regions to enable more effective surveillance and control. The accelerated development of genomics, transcriptomics, proteomics, and metabolomics facilitated the new systems-level interrogation of PRRSV-host interaction. Omics integration will reveal the molecular mechanisms in viral replication, immune modulation, and pathogenicity. Comparative genomics analysis began to define the significant mutations in virulence and immune evasion, and transcriptome and proteome profiling demonstrate host cellular responses and immune reprogramming induced by infection. Future studies combining omics data
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