Detection of BLV Viral RNA in Blood Samples of Naturally infected Cattie

ALVAREZ IRENE; NATALIA PORTA; GERONIMO GUTIERREZ; JAWORSKI JUAN PABLO; TRONO, KARINA

Tokio

Conferencia; 18th International Conference on Human Retrovirology:HTLV and Related Viruses; 2017

Alvarez Irene, Porta Natalia, Gutierrez Geronimo, Jaworski Juan Pablo, trono KarinaDetection of BLV Viral RNA in Blood Samples of Naturally infected CattieBovine leukemia virus (BLV) is responsible for B cell lymphosarcoma in adult cattle. Viral expression in vivo is considered to be restricted to extremely low levels and mitosis of infected B lymphocytes is actually considered to be the main mode of virus persistence within the infected host. As consequence, proviral load is the current marker for infection monitoring and prediction of the transmission potential of cattle within herds. The use of a segregation according to in vivo level of infection as a control strategy depends on the stability of provial load but also on the absence of circulating virus. Epidemiological data within dairy herds suggest that could be certain moments when infection could be not stable on infected individuals and then be involved in rapid within herd transmission, such as the time around delivery, when highly susceptible hosts got rapidly infected when enter the milking herd.In this study we investigated the presence of virus and provirus in blood from seven asymptomatic BLV infected cattle during one year, passing through one whole milking cycle and two delivery time points. Total RNA and DNA was extracted from fresh whole blood. nPCR was performed using primers to amplify the conserved Tax and pol regions. Real-time PCR was performed and cDNA samples (?). Template RNA weas treated with DNAse enzyme to eliminate any DNA contamination after extraction.Samples from 4 cows were positive for RNA in plasma at different time point, being the delivery moment a constant finding between them. Proviral load showed to be stable except in 1 cow where showed a significant increase in the middle of the milking cycle, 6 months after delivery. This study describes for the first time the detection of free BLV RNA in plasma from BLV-infected asymptomatic cows, suggesting the occurrence of BLV viral reactivation and replication within the asymptomatic period. Even if BLV RNA was rarery detected in blood other transmission pathways than cell-related contact should be further investigated.