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Schmallenberg virus (SBV), a teratogenic orthobunyavirus that infects predominantly ruminants, emerged in 2011 in Central Europe, spread rapidly throughout the continent, and subsequently established an endemic status with re-circulations to a larger extent every 2 to 3 years. Hence, it represents a constant threat to the continent’s ruminant population when no effective countermeasures are implemented. Here, we discuss potential preventive measures to protect from Schmallenberg disease. Previous experiences with other arboviruses like bluetongue virus have already demonstrated that vaccination of livestock against a vector-transmitted disease can play a major role in reducing or even stopping virus circulation. For SBV, specific inactivated whole-virus vaccines have been developed and marketing authorizations were granted for such preparations. In addition, candidate marker vaccines either as live attenuated, DNA-mediated, subunit or live-vectored preparations have been developed, but none of these DIVA-capable candidate vaccines are currently commercially available. At the moment, the licensed inactivated vaccines are used only to a very limited extent. The high seroprevalence rates induced in years of virus re-occurrence to a larger extent, the wave-like and sometimes hard to predict circulation pattern of SBV, and the expenditures of time and costs for the vaccinations presumably impact on the willingness to vaccinate. However, one should bear in mind that the consequence of seronegative young animals and regular renewed virus circulation might be again more cases of fetal malformation caused by an infection of naïve dams during one of their first gestations. Therefore, an appropriate and cost-effective strategy might be to vaccinate naïve female animals of all affected species before the reproductive age. Full article

The Peribunyaviridae family contains the genera Orthobunyavirus, Herbevirus, Pacuvirus, and Shangavirus. Orthobunyaviruses and pacuviruses are mainly transmitted by blood-feeding insects and infect a variety of vertebrates whereas herbeviruses and shangaviruses have a host range restricted to insects. Here, we tested mosquitoes from a tropical rainforest in Mexico for infections with peribunyaviruses. We identified and characterized two previously unknown viruses, designated Baakal virus (BKAV) and Lakamha virus (LAKV). Sequencing and de novo assembly of the entire BKAV and LAKV genomes revealed that BKAV is an orthobunyavirus and LAKV is likely to belong to a new genus. LAKV was almost equidistant to the established peribunyavirus genera and branched as a deep rooting solitary lineage basal to herbeviruses. Virus isolation attempts of LAKV failed. BKAV is most closely related to the bird-associated orthobunyaviruses Koongol virus and Gamboa virus. BKAV was successfully isolated in mosquito cells but did not replicate in common mammalian cells from various species and organs. Also cells derived from chicken were not susceptible. Interestingly, BKAV can infect cells derived from a duck species that is endemic in the region where the BKAV-positive mosquito was collected. These results suggest a narrow host specificity and maintenance in a mosquito–bird transmission cycle. Full article