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Selective breeding for resistance to Maedi Visna Virus (MVV)

Solution name: Selective breeding for resistance to Maedi Visna Virus (MVV)

Aim: Monitoring and eradicating MVV by selective breeding

Description: Maedi-visna (MV) in sheep and caprine arthritis encephalitis (CAE) in goats are caused by small ruminant lentiviruses (SRLVs). SRLVs affected animals may remain asymptomatic carriers and only a proportion of them will display clinical disease, mainly characterized by chronic respiratory symptoms (Maedi), neurological signs (Visna and CAE) or arthritis (CAE). So far, the control plans are based on serological diagnosis at scheduled intervals, gradual and early culling of seropositive animals as well as suckling newborn lambs only from the seronegative ewes, after being separated at birth from the infected mother. In addition, the introduction of animals in the flock is allowed only for the seronegative animals. Recently,  E154K polymorphism in the gene coding for transmembrane protein type 154 (TMEM154) has been reported  to be associated  with the serological status and/or the provirus concentration of SRLVs exposed sheep. Sheep carrying the KK genotype are resistant, while those with the EK and EE genotypes are susceptible. This finding allows to envisage an alternative control plan based on selective breeding.

Topic: health

Production:  Dairy / Meat

Animal Category: Adult / Lamb / Replacement

Issue: Iceberg diseases (e.g. OPA, CLA, Johnes disease, Maedi Visna, Border disease)

Level of Solution: Knowledge

Country: Italy






How to implement it
  1. Sampling breeding animals (preferentially rams) as younger as possible to extract DNA (nasal swabs by genotube are the less costly procedure). Take care of a correct animal identification (EID is recommended).
  2. Sending the samples to specialised labs for DNA extraction and genotyping (high throughput and economic TAQMAN assays are available)
  3. Selecting KK (EK as second option) animals for breeding
  4. Keeping replacement preferentially from KK (EK as second option) sires and dams.


According to cost/benefits and the desired efficiency of the breeding and eradication program, farmers may:

  •  Genotype just breeding males;
  • Genotype both breeding males and females
  • Genotype the whole flock for either selecting breeding animals or culling
      Expected benefits

      Stable and definitive control and eradication of MVV avoiding the laborious and costly traditional plans

      Prerequisites and/or limits

      Long term results

      Breeding organisation to manage sampling and genotyping in the correct timing

      Specialised labs for DNA extraction and genotyping

      Validation study to confirm the genetic determinism in the specific population/breed

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