Veterinary Preventive Medicine-II

DIAGNOSIS

Samples to be collected

• Live animals- nasal swabs or genital swabs or conjunctival swabs during the acute phase of infection, aborted materials, tissue samples from the fetal liver, brain, and spleen, semen, placenta, uterine mucus and serum
• Dead animals- Lymph nodes, liver, lungs, brain, aborted foetal liver, brain and spleen

Based on clinical signs

Identification of the agent

• The virus can be isolated from nasal swabs or genital swabs, from animals with vulvovaginitis or balanoposthitis, taken during the acute phase of the infection, and from various organs collected at post-mortem.
• For virus isolation, various cell cultures of bovine origin are used, for example, secondary lung or kidney cells or the Madin–Darby bovine kidney cell line.
• The virus produces a cytopathic effect in 2– 4 days. It is identified by neutralization or antigen detection methods using monospecific antisera or monoclonal antibodies.
• Viral DNA detection methods have been developed, and the polymerase chain reaction technique is increasingly used in routine diagnosis.

Serological tests

• The virus neutralisation test and various enzyme-linked immunosorbent assays (ELISA) are most widely used for antibody detection.
• ELISA antibodies can be detected in serum and with lower sensitivity in milk.
• Fluorescent antibody technique (FAT) and electron microscopy can be made for diagnosis of disease.