Detection of bovine herpesvirus type 4 antibodies and bovine lymphotropic herpesvirus in New Zealand dairy cows

Abstract

AIM: To detect the presence of bovine herpesvirus (BoHV) type 4 in New Zealand dairy cows with clinical metritis.

METHODS: Serum samples taken from 92 dairy cows with clinical metritis, each from a different farm, were tested for the presence of antibodies against BoHV-4 using a commercially available, indirect ELISA. Peripheral blood mononuclear cells (PBMC) were collected from 10 BoHV-4 seropositive cows, and PBMC were examined by a pan-herpesvirus nested PCR to detect herpesvirus. PCR products were sequenced directly and a proportion of the PCR products were cloned and sequenced to identify the virus present.

RESULTS: Antibodies to BoHV-4 were detected in 23/92 (25%) serum samples. The pan-herpesvirus PCR was positive in 8/10 PBMC samples. Cloning and sequencing identified that all of the eight PCR-positive PBMC contained bovine lymphotropic herpesvirus (BLHV); no BoHV-4 DNA was detected.

CONCLUSIONS: This study reports the finding of the presence of apparent antibodies to BoHV-4, and BLHV DNA in New Zealand dairy cows affected by metritis.

CLINICAL RELEVANCE: Bovine herpesvirus type 4 and BLHV are reported to have the potential to cause reproduction failure in cows. This is the first report of apparent BoHV-4 antibodies, and BLHV in New Zealand. The importance and epidemiology of these viruses in cattle in New Zealand requires further investigation.

KEY WORDS:

• Bovine herpesvirus type 4
• BoHV-4
• bovine lymphotropic herpesvirus
• BLHV
• metritis
• dairy cows
• detection
• ELISA
• cloning
• peripheral blood mononuclear cells

Acknowledgements

The cooperation of the farmers is gratefully acknowledged. This study was funded by Cognosco, Anexa Animal Health, Morrinsville and AgResearch, Hopkirk Research Institute, Palmerston North. The collection of the serum samples was funded by Pfizer Animal Health NZ LTD and Pfizer VMRD as part of another study. For biosecurity reasons, Andrew McFadden and David Pulford of the Investigation and Diagnostic Centre, Ministry of Primary Industries were involved in the confirmation of BLHV using pathogen-specific PCR assays.

Notes

1 D. Pulford, MPI, Upper Hutt, New Zealand.