Image caption Farmers are concerned about heavy losses during the lambing season

A synthetic version of the Schmallenberg virus has been made in the laboratory by Scottish scientists.

The research raises hopes for developing a vaccine for the livestock disease, which causes lambs and calves to be stillborn.

Schmallenberg virus (SBV) was discovered little more than a year ago in Germany, but has now spread to several European countries.

About 1,000 farms have reported cases across England and Wales.

Some farmers are reporting heavy losses as the lambing season gets underway.

Schmallenberg virus Discovered in the German town of Schmallenberg in November 2011

Spread rapidly to many European countries, including the Netherlands, Belgium, France and the UK

Though to be spread by infected midges

SBV causes relatively mild illness in adult cattle and sheep, but where infection takes place during the early stage of pregnancy it can result in congenital disorders of lambs and calves, and stillbirths

One of a class of emerging viruses spread by insects (arboviruses)

The European Centre for Disease Prevention and Control suggests that there is a low likelihood of any risk to public health

Scottish researchers, led by Massimo Palmarini and Alain Kohl from the University of Glasgow, made a synthetic version of the virus in the laboratory to study its genetics and how it infects farm animals.

Their experiments show the virus replicates in the brain cells and spinal cords of unborn animals, if the virus is passed to calves or lambs during pregnancy.

The researchers manipulated the genetic sequence of the virus to create versions that were more or less virulent.

They say their work raises hopes for developing a vaccine for the livestock disease.

Prof Massimo Palmarini of the MRC-University of Glasgow Centre for Virus Research told BBC News: "This is the first time we have been able to manipulate the genome of SBV in this way.

"We now know much more about how the virus causes the disease than we did a couple of months ago."

Farming concerns

SBV was discovered in the German town of Schmallenberg in November 2011.

Cases in the UK were reported in January last year, with the virus spreading across England and Wales during the summer.

Image caption Neurons infected with SBV

It was believed the virus was carried to England by midges blown across the Channel and was then spread by native midges during the summer, government scientists have said.

Farmers are on alert for the condition during this year's lambing season. The first sign is often when livestock give birth to deformed or dead young, which can be months after the infection has occurred.

A vaccine for SBV developed by MSD Animal Health has been submitted to European regulators for approval.

A spokesperson said: "In the studies to date, safety and efficacy has been demonstrated in calves, lambs and pregnant ewes.

"The company is currently working closely with the regulatory authorities and we cannot speculate when the vaccine will be available. "

The Scottish research was funded by the Medical Research Council and Wellcome Trust.