Diagnosis of Bovine Herpesvirus-1 Infection in Cattle

The clinical signs in young cattle in a feedlot are only indicative of BoHV-1 infection. Many other respiratory diseases may also cause the same or similar signs. For a definitive diagnosis laboratory tests are required.

Virus isolation

Detection of BoHV-1 can be performed in various specimens: swabs (nasal, vaginal), sperm, tissue samples collected from dead or aborted animals.

Serology

Antibodies against BoHV-1 can be detected at 2-6 weeks post-infection. The method antibody detection depends on the vaccination status of the herd. Virus neutralisation (VN) and ELISA tests are available.

Using VN retrospective diagnosis of BoHV-1 infection can be made by measuring antibody titres in paired sera samples. First sample is collected during the clinical phase and a second sample is collected 4 weeks later. It is not possible to differentiate VN antibody titers induced by the vaccine (marker and non marker) from antibodies induced by field infection.

Two types of BoHV-1 ELISA tests are currently available:

• Type 1 detects antibodies against gB - cannot differentiate between field infection and vaccination with both marker and non-marker vaccines.
• Type 2 detects antibodies against gE - possible to differentiate between field infection and vaccination with a marker vaccine.

Both gB and gE antibodies can be measured in serum and milk samples. Antibodies against gB are developed earlier than gE antibodies (2-3 weeks difference), meaning that gB antibodies can be detected earlier.

In situations when animals are likely to be sero-positive for BoHV-1 because of maternal antibodies, vaccination or previous infection, paired serum samples are required to diagnose an acute BoHV-1 infection.