Genetic characterization of bovine viral diarrhoea viruses isolated from cattle in South Africa

..................................................................................................................1 CHAPTER 1 : INTRODUCTION..............................................................................2 CHAPTER 2 : LITERATURE REVIEW...................................................................8 2.1 Virus characteristics ............................................................................... 8 2.2 Epidemiology ......................................................................................... 11 2.2.1 Distribution................................................................................................11 2.2.2 Sources of infection .................................................................................11 2.2.3 Transmission ............................................................................................12 2.2.4 Host susceptibility ....................................................................................13 2.3 Pathogenesis.......................................................................................... 14 2.3.1 Acute BVDV infections .............................................................................15 2.3.2 Persistent Infection...................................................................................15 2.3.3 Mucosal disease .......................................................................................16 2.4 Clinical signs and economic effects with special reference to southern Africa ...................................................................................... 16 2.5 Diagnosis................................................................................................ 17 2.5.1 Virus isolation ...........................................................................................18 2.5.2 Antigen detection......................................................................................18 2.5.2.1 Immunofluorescence staining................................................................18 2.5.2.2 Immunohistochemical staining ..............................................................19 2.5.2.3 Flow cytometry ......................................................................................20