A Milk-Based MicroRNA Assay to Stratify BLV Infectiousness in Dairy Cattle

Milk samples are a rich matrix of diagnostically relevant biomarkers that capture the acute physiology of the dairy cow. Almost all serological ELISAs are applicable in milk and, as forensic technologies continue to become a superior diagnostic tool in the dairy industry, the use of genetic markers in milk are becoming the forefront of dairy molecular diagnostics. Established national DHI sampling platforms present an excellent opportunity to diagnose millions of BLV-infected animals without the need for additional sampling. Our recent work characterizing BLV-derived microRNAs in blood cells has prompted us to explore potential diagnostic applications in milk because BLV microRNAs are (1) highly expressed (2) unique from host microRNAs (3) implicated in BLV pathogenesis and thus we anticipate that they will more informative of disease progression and infectiousness than BLV antibodies or PVL alone.The goal of our Phase I research and development efforts is to determine the correlation of BLV microRNA abundance in milk with infectiousness as determined by proviral load and lymphoncyte count. Secondly, high-throughput RNA isolation from milk and streamlined methods will be developed to quantify BLV microRNA expression. This assay will be validated for its accuracy and utility to dairy producers in identifying the most advanced and infectious animals within their herds. Following the validation phase, this assay will be used in a Phase II SBIR to conduct a large-scale field trial, enrolling DHI herds throughout the nation who are motivated to eradicate BLV from their herds.Currently, U.S. dairy producers are without informative diagnostic solutions to effectively manage the high prevalence of BLV within their herds leading to a lack of emphasis or awareness of the disease and associated economic impact. Commercialization of this assay will provide an in-line diagnostic solution for identifying the sickest and most infectious cattle with no additional sampling. Agencies such as the U.S. Animal Health Association could utilize this assay in a national BLV eradication program and change how the U.S. dairy industry addresses BLV. This work is ideally suited for a USDA SBIR Phase I research and development project by delivering a commercially available solution to a wide-spread problem that affecting the sustainability of the US dairy industry.