Bovine alphaherpesvirus 1 (BHV-1 or BoAHV-1) is also known as IBR or IPV virus and causes the corresponding clinical pictures, either the respiratory infection “infectious bovine rhinotracheitis” or the genital infection “infectious vulvovaginitis/balanoposthitis”. Clinical symptoms may be absent in infected adult cattle or can be mild with a slightly reduced general condition. Nonspecific signs such as inertness, reduced milk yield and mild respiratory symptoms may accompany the confrontation with the virus. However, in calves and, more rarely, even in adult cattle, severe illnesses of larger parts of the herd combined with individual deaths are possible. The latter is usually observed as a factor disease in combination with stress and secondary bacterial infections. The genital form of the disease has been successfully suppressed by the use of artificial insemination.
As a typical representative of the herpesviruses, BoHV-1 is able to withdraw into the nerve nodes at the site of entry after the primary infection and persist there for life. Under the influence of stress (transport, birth, illness, herd regrouping), virus replication and excretion can resume without the affected cattle showing signs of illness (reactivation). Infected animals, so-called reactors, represent as a virus reservoir a permanent potential threat to the spread of the infection.
Infection is mainly transmitted directly via animal contact and animal trade, but can also occur indirectly for a short period of 1-2 days through contaminated clothing and footwear, instruments and vehicles. Biosecurity and hygiene measures must therefore be regarded as key pillars in preventing the introduction and spread of BoHV-1 re-infection events. Airborne transmission over long distances is not successful in spreading BoHV-1.
Due to its economic importance, great efforts have been made in some European countries to eradicate the disease from the cattle population. Countries such as Denmark, Finland, Norway, Sweden, Austria and Switzerland have achieved a “BoHV‑1 free” status for decades. Since June 2017, the whole of Germany has also been officially designated “BoHV-1 free” after 20 years of intensive BoHV-1 control (Map). This free status provides trade guarantees and advantages and is linked to a general vaccination ban and a minimum proportion of 99.8 % BoHV-1-free farms. In 2020, the Czech Republic also qualified for the BoHV-1-free status.
In Germany, glycoprotein E (gE) deletion vaccines were used as part of the BoHV-1 control program, which allow discrimination between vaccinated and field virus-infected cattle by the detection of gE-specific antibodies. These vaccines are known as DIVA vaccines (Differentiating Vaccinated from Infected Animals). Over the years, vaccination has successfully reduced the spread of the field virus in infected regions and herds without compromising the accompanying diagnostics.
Prophylactic vaccinations have been banned in Germany since 2015. In outbreak holdings, emergency or suppressive vaccinations may be ordered by the competent authorities in individual cases. Depending on the size of the herd, the stage of infection, the degree of infestation and the structural and personnel situation, vaccination can be used to support measures to contain the spread of the disease until the reactors have been eliminated.
According to the EU Animal Health Act (Regulation (EU) 2016/429 and the Delegated Regulation (EU) 2018/1882 Annex), BoHV-1 is assigned to pathogen groups C, D and E. BoHV-1 is a listed disease in accordance with Article 9(1)(c) of Regulation (EU) 2016/429, which is relevant for some Member States and for which measures must be taken to prevent it from spreading in areas of the EU that are officially disease-free or where appropriate eradication programs are in place. In practice, this means that, as before, all bovidae are included in the BoHV-1 testing obligation. A classification into categories D and E with mandatory entry and surveillance tests also applies to camelids and cervids in addition to bovidae.
- Direct contact for federal and state authorities on issues relating to BoHV-1 control in collaboration with specialists from the Institute of Epidemiology at the FLI
- Virus or genome detection in sample material
- Sequence determination of virus isolates
- BoHV-1 antibody detection to reassess unclear results
- Provision of BoHV-1 virus strains, reference material (blood, milk, meat juice) and BoHV-1-specific monoclonal antibodies
- Review, standardization and further development of BoHV-1-specific test methods
- Approval and batch testing of BoHV-1 diagnostics
- Implementation of qualification measures, e.g. for employees of testing laboratories
- Carrying out national and international proficiency tests
- Participation in international and WOAH ring tests
- Participation in working groups and research projects of the European Union
- Virus detection in cell culture (virus isolation) and immunofluorescence analysis
- Genome detection using multiplex real-time PCR for differentiation of field and vaccine virus as well as conventional PCR; differentiation of herpesviruses using a PanHerpes PCR
- Strain characterization by restriction enzyme fragment length polymorphism (RFLP) analysis
- Differentiating neutralization assay and plaque reduction tests
- Antibody detection by neutralization test and ELISA: differentiating antibody analyses by gB-blocking ELISAs, indirect ELISAs and gE-blocking ELISAs
- Panel of more than 200 defined BoHV-1 reference sera
- German BoHV-1 reference sera: R1 (strong positive), R2 (positive), R3 (weak positive) and R31 and R32 (negative)
- German reference milk samples for use in pools of 50 and 100: R26 (positive), R27 (weak positive), R28 (positive), R29 (weak positive), R30 (negative)
- Meat juice reference material: strong and weak positive, negative
- Various BoHV-1 reference strains
- Collection of related ruminant herpesviruses (BuHV-1, BoHV-5, CvHV-1, CvHV-2, CpHV-1)