Defining Criteria for Transmission Risk Classification Based on Proviral Load Targeting the pol Gene in the Bovine Leukemia Virus

Abstract

In this study, we aim to establish new criteria for classifying the transmission risk using the pol method, one of the three commercially available kits (the tax, LTR and pol methods) used for measuring the proviral load of bovine leukemia virus (BLV). We compared proviral values measured by each kit under different conditions using BLV-positive samples, and it was suggested that the tax method was relatively prone to variablity in measured values. Then, based on a single regression analysis of the LTR and pol methods, the classification criteria for the pol method were set as follows: 12,000 or more copies per 100,000 cells is high risk, 3,000 to 12,000 copies is intermediate risk, 600 to 3,000 copies is low risk, and less than 600 copies is very low risk. The results of classification using these criteria were in general agreement with the results of the LTR method, and more than 90% of infected cattle with lymphocytosis were classified into the high risk group, suggesting that this method may be useful for the control and prevention of BLV infections on farms.