Development of an indirect immunofluorescence assay for diagnosis of bovine viral diarrhoea virus on ear notch tissue samples in cattle infected persistently.

Bovine viral diarrhoea virus (BVDV) causes a disease that has a wide range of clinical symptoms in domestic and wild ruminants. It is a major problem in cattle and causes significant economic losses in the cattle industry. The virus infects bovines of all ages and causes both immunosuppression and reproductive, respiratory and digestive disorders. Cattle infected persistently, as a continuing source of the virus and the main factor in transmission of the disease between and among herds, are the main source of BVDV and a primary factor in the epidemiology of the disease. To determine whether a BVDV infection is persistent, two samples should be taken at 3-4 week intervals and tested for the virus antigen. Animal sera, whole blood, organ and ear notch tissue samples can be used for BVDV diagnosis. In ear notch tissue, viral antigen can be detected by an antigen enzyme-linked immunosorbent assay (antigen ELISA), immunohistochemistry (IHC) and reverse-transcription polymerase chain reaction (RT-PCR). This paper describes the development and implementation of an indirect immunofluorescence (IF) method using ear notch tissue samples for diagnosis of cattle infected persistently. Results obtained by this method show that IF is a good alternative to RT-PCR and antigen ELISA and can be a quick and accurate method in diagnosis of BVDV in cattle infected persistently with this virus.