avian & livestock assay data sheet

Bovine leukemia virus ("bovine enzootic leukosis")

Test code: S0196 - Ultrasensitive qualitative detection of bovine leukemia virus by real time polymerase chain reaction

Bovine leukemia virus (BLV) is an exogenous retrovirus that is similar to primate T-cell lymphotropic viruses 1, 2, and 3 (PTLV-1, -2, and -3), and human T-cell lymphotropic viruses 1 and 2 (HTLV-1 and -2). Cattle infected with BLV can develop a persistent infection with virus replication in B lymphocytes. The infection is transmitted through the transfer of infected cells via direct contact, through milk, and possibly by insect vectors.

Most infected animals remain sub-clinical. In these asymptomatic animals, less than 1% of peripheral blood mononuclear cells (PBMCs) and up to 10% of the circulating B lymphocytes are found to be infected. In 20–30% of infected animals, a permanent increase in the number of B lymphocytes in the peripheral blood can be detected. The increase in B-lymphocytes results from the polyclonal expansion of untransformed lymphocytes. However, a significant number of lymphocytes in these infected animals contain provirus. Clinical signs of malignant lymphoma become evident as tumors invade various lymphoid tissues resulting in enlarged lymph nodes, weight loss, decreased milk production, fever, and loss of appetite.

Bovine leukemia virus is quite prevalent worldwide and causes significant economic impact on the dairy cattle industry due to reduced milk production, increased replacement costs, reduced conception rates, and greater susceptibility to other infectious diseases such as mastitis, diarrhea, and pneumonia.

Direct antigen detection methods have been used in the past to detect this virus and screen for infected cattle but those methods are not very sensitive. However, molecular detection by PCR (Heenemann et al., 20112) is highly sensitive, specific and rapid.

Utilities:

• Help confirm the disease causing agent
• Identify bovine leukemia virus carriers
• Help ensure that herds and populations are free of bovine leukemia virus
• Early prevention of spread of this virus among animals
• Minimize human exposure to this virus
• Safety monitoring of biological products that derive from animals

References:
Heenemann, K., Lapp, S., Teifke, J.P., Fichtner, D., Mettenleiter, T.C., and Vahlenkamp, T.W. (2012) Development of a bovine leukemia virus polymerase gene-based real-time polymerase chain reaction and comparison with an envelope gene-based assay. J. Vet. Diagn. Invest. 24:649-655.

Specimen requirements: 0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml fresh, frozen or fixed tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected