Insemination with border disease virus-infected semen results in seroconversion in cows but not persistent infection in fetuses

Abstract

Background: This study examined various health variables in cows after artificial insemination with Border disease virus (BDV)-infected semen and the occurrence of persistent infection in ensuing fetuses. Five cows were inseminated (day 0) with BDV-infected semen as well as with semen from a fertile Eringer bull. One cow, inseminated with virus-free semen only, served as a control. Clinical examination, assessment of eating and rumination activities, measurement of intraruminal temperature and leukocyte count were used to monitor the health of the cows. Blood samples were collected at regular intervals for the detection of viral RNA and antibodies against BDV, and the cows were slaughtered on day 56. The uteri, placentae and fetuses were examined macroscopically, histologically, immunohistochemically and by means of molecular methods for the presence of pestiviruses.

Results: The demeanour, eating and rumination activities and intraruminal temperature were not affected by insemination with BDV-infected semen, whereas the total leukocyte and lymphocyte counts dropped transiently and were significantly lower on day 6 than on day 0. Seroconversion occurred by day 28 in the five infected cows but not in the control cow. The uteri, placentae and fetuses had no macroscopic or histological lesions, and immunohistochemical examination and RT-PCR were negative for pestiviruses.

Conclusions: The findings showed that cows inseminated with BDV-infected semen seroconverted and fetuses thus produced were not persistently infected. Transmission of BDV to cattle through infected semen, therefore, seems to be of minor importance.

Keywords: BDV; Border disease virus; Cattle; Insemination; Persistent infection; Pestivirus; Semen; Seroconversion.

Fig. 1

Daily rumination time from 5 days before until 15 days after insemination in 5 cows artificially inseminated with BDV-infected semen (mean ± SD) and 1 control cow. The yellow bar represents the reference interval (370 to 511 min) established in 300 healthy cows [15]

Fig. 2

Intraruminal temperature from 2 days before until 20 days after insemination in 5 cows artificially inseminated with BDV-infected semen (mean ± SD) and 1 control cow. The yellow bar represents the reference interval (38.0 to 39.0 °C) for the rectal temperature [32]

Fig. 3

Total leukocyte count from 2 days before until 24 days after insemination in 5 cows artificially inseminated with BDV-infected semen (mean ± SD) and 1 control cow. The yellow bar represents the reference interval (5 to 10 × 10³/μl blood) [33], * = different from day 0 (P < 0.05)

Fig. 4

Lymphocyte count from 2 days before to 24 days after insemination in 5 cows artificially inseminated with BDV-infected semen (mean ± SD) and 1 control cow. The yellow bar represents the reference interval (2.5 to 5.5 × 10³/μl blood) [33], * = different from day 0 (P < 0.05)

Fig. 5

Relative optical density (OD) in the ELISA for pestivirus antibody in the serum of 5 cows inseminated with BD virus-infected semen and a control cow from day 0 to day 56 of the infection phase expressed as a percentage to the OD of a standard serum. Relative OD values > 30% (dotted line) are defined as positive