Bovine leukemia virus (BLV), a member of the genus Deltaretrovirus, causes chronic tumor-associated disease in cattle and represents a significant threat to the bovine industry. Existing laboratory diagnostics such as agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA) are established but are limited by complex workflows, lengthy processing times, and cost. Those constraints reduce feasibility for rapid, onsite diagnosis in field or resource-limited settings. To address these gaps, the investigators developed a rapid visual lateral flow immunoassay (LFIA) that uses latex microspheres as signal labels and the BLV gp51 protein as the capture antigen.
The LFIA reported in the study employs the BLV gp51 protein as the antigen to capture anti-BLV antibodies from bovine serum. Latex microspheres (LM) function as the colored signal label, enabling a visual readout on the lateral flow strip. The assay format and use of LM were chosen to support a user-friendly, rapid, and equipment-free detection method suitable for point-of-care or on-farm screening.
Analytical sensitivity was assessed using a positive standard serum. The LFIA detected the positive standard serum at a dilution of 1:256, demonstrating the assay’s capacity to identify BLV-specific antibodies at relatively high dilutions. This reported detection limit indicates the LFIA can identify seropositive samples without laboratory amplification or complex instrumentation.
The developers conducted a parallel evaluation comparing the LFIA with a commercial ELISA using 138 bovine serum samples. The LFIA results were compared against the ELISA reference method, and the study reported a strong correlation between the two assays. The observed concordance rate between LFIA and ELISA was 96.37%, and inter-test agreement measured by kappa was reported as 0.89, indicating substantial to near-perfect agreement in the assessed sample set.
Diagnostic metrics reported in the study include a relative sensitivity of 87.09% and a relative specificity of 99.06% for the LFIA when compared to the ELISA reference. The high specificity suggests a low false-positive rate in the evaluated population. The authors also reported no cross-reactivity with other tested bovine pathogens, supporting the assay’s analytical specificity for BLV antibodies in the contexts examined.
Stability testing reported for the LFIA showed that the assay maintained consistent accuracy and functional performance for at least 90 days when stored at 4 °C and for at least 70 days at 37 °C. These stability observations indicate potential robustness of the LFIA under refrigerated and elevated-temperature conditions relevant for transport and storage in field settings.
Given the LFIA’s visual readout, use of latex microsphere labels, and reported diagnostic characteristics, the assay offers an efficient approach for rapid on-site screening of BLV in cattle. The combination of high specificity, reasonable sensitivity, strong agreement with commercial ELISA, and demonstrated stability supports its potential utility for surveillance and preliminary diagnosis in resource-limited environments or where rapid decisions are needed. The authors highlight the LFIA as a practical tool that could aid BLV diagnosis and control measures at the point of care.
Details not reported in the abstract include full methodological parameters (for example, exact strip construction, sample volume, incubation times, or the full list of pathogens tested for cross-reactivity) and comprehensive demographic or geographic information for the 138-sample panel. Those methodological specifics and expanded validation data are not available in the provided source text. The authors declared no competing interests in the published article.