Detection of Schmallenberg virus serum neutralising antibodies

Schmallenberg virus (SBV) emerged in continental Europe in late 2011, and further work is required to assess the prevalence of SBV throughout Europe. Since its detection in Germany, SBV has now been detected in other European countries, including the United Kingdom. Infection with SBV can cause mild clinical signs in ruminants, including diarrhoea and reduced milk yield. However, the virus can have a devastating effect on the developing foetus leading to malformation in newborn offspring. This is a feature shared by other members of the Simbu group of orthobunyaviruses. Since disease in adult animals can be inapparent, serology offers the best method for monitoring for the presence of SBV and assisting in livestock management. This protocol describes a method for initial titration of SBV on African Green Monkey kidney (Vero) cells, and a plaque reduction neutralisation test (PRNT) for the detection of neutralising antibodies against SBV in cattle and sheep sera. This assay can be used to screen ruminant sera in order to confirm exposure to the virus, and the results obtained are comparable to a recently developed commercial enzyme linked immunosorbent assay (ELISA). Thus, these two assays constitute an effective diagnostic tool-box for providing confirmation of exposure to SBV.