A deadly, previously unknown virus that triggers abortions in sheep, goats and cattle, is spreading around Europe, causing more trouble for the beleaguered livestock industry. But farmers may have a vaccine to fight it with by next year. Virologists are meeting in Lelystad, the Netherlands, this week to discuss Schmallenberg virus, which belongs to a virus family never seen in Europe before. Three companies are already testing candidate vaccines. Normally these would take years to come to market but faster approval could stop the virus taking hold. Since Schmallenberg was identified in Germany last November, it has caused a wave of sheep abortions across northern Europe and the UK and has now spread to Italy. The subgroup of the family to which the virus belongs includes Oropouche virus, which infects humans and is the second-most common cause of fever in tropical South America after dengue. Schmallenberg’s closest relatives, such as Akabane virus found in Japan, Australia and Israel, only infect ruminants, however, so it is thought unlikely to infect humans. The last animal virus to take Europe by surprise was bluetongue, which like Schmallenberg is spread by biting midges and exploded in the same regions of Germany, the Netherlands and Belgium in 2007. Accelerated approval for a vaccine cleared bluetongue from Europe by 2010.
A sense of urgency might also stop Schmallenberg settling in. “All the tests required for licensing a vaccine would take two years,” says Peter Mertens, head of insect-borne viruses at the Institute for Animal Health in Pirbright, UK. If governments lift the more onerous testing requirements, vaccines might be permitted after being given to animals and observed for long enough to see if they are safe, induce effective antibodies and prevent infection. In Lelystad, however, researchers will focus on better ways to detect antibodies to the virus, says Martin Beer of the Friedrich Loeffler Institute in Insel Riems, Germany, which first isolated the virus and proved its link to disease. Antibodies reveal which animals have been infected. Rapid tests in time for when midges return in spring will show where the virus spreads. An antibody test can also tell researchers when the virus has caused a fetus to be malformed, says Beer. Right now, that is not clear because the virus itself has cleared by the time the animal is delivered. The tests will also prove which animals are safe for export.
March 20, 2012
Original web page at New Scientist