Recent Advances in Immunological and Biosensing Approaches for Sensitive Detection of Citrus tristeza virus

Abstract

Citrus tristeza virus (CTV) is among the most devastating viruses of citrus crops worldwide that create significant losses by rapid decline, stem pitting, seedling yellows and quality reduction of fruit. Widespread distribution of the virus, its genetic variation, and efficient aphid-mediated transmission have made early and accurate detection of virus crucial for disease management. Biological indexing and serological tests like ELISA, DIBA, DTBIA and immunoelectron microscopy have been very useful in large-scale screening programs due to their simplicity and low cost. There have been some limitations of sensitivity, specificity and strain differentiation, however, that have spurred the advancement of more sophisticated molecular and immunological methods. There have been recent advancements in CTV detection with RT-PCR, real-time PCR, loop-mediated isothermal amplification (LAMP), or droplet digital PCR (ddPCR), which has greatly enhanced the specificity and sensitivity of the detection. Immunodiagnostic systems have been improved by the development of antibody engineering technologies such as monoclonal antibody panels, recombinant antibodies, single-chain variable fragments (scFv), nanobodies, and epitope-guided antibody design during the same period. Advances in emerging biosensing and nanotechnology-based platforms like gold nanoparticle immunosensors, electrochemical and optical biosensors, CRISPR based systems, fluorescent nanoprobes, and microfluidic lab-on-a-chip are also revolutionizing plant virus detection by providing highly sensitive, portable, and rapid detection in the field. This review highlights the genomic structure and the coat protein structure of CTV, its transmission method, conventional and advanced diagnostic techniques, advancement in antibody engineering and nanotechnology based diagnostic platforms. Furthermore, a comparative study of diagnostic systems according to their sensitivity, specificity, cost, feasibility, complexity and applicability in the field is provided to show their practical importance in the context of current citrus disease surveillance and management.