Table 2 Overview of experimental and field studies with Schmallenberg virus in domestic ruminants contributing to our understanding of the efficacy of transplacental crossing, the capacity to induce congenital malformations, and the relationship between clinical and pathological malformations observed at birth in offspring and the moment of gestation at which the dam became infected
Study type | Virus strain | Species | No. studied | Inoculation route | Stage of gestation (day) at infection | Stage progeny examined | Major Outcome | Reference | |
|---|---|---|---|---|---|---|---|---|---|
Exp. | Field | ||||||||
+ | FLI inoculuma | Cattle | 24 | Sub-cutaneous | 60-150 | 6 weeks PI | Preliminary data; indications for efficient placental crossing but limited capacity to induce malformations | Schmallenberg virus: Final Report EU, 2014c | |
+ | FLI inoculuma | Cattle | 11 | Sub-cutaneous | 105-120 | 10-28 DPI | Preliminary data; indications for efficient placental crossing but limited capacity to induce malformations | Schmallenberg virus: Final Report EU, 2014c | |
+ | Field | Cattle | 71 | Vector-mediated | 13-162 | At birth | Evidence of transplacental SBV infection only found in 13% of calves at birth; only 1 calf with malformations | [69] | |
+ | Field | Cattle | 36 | Sub-cutaneous | 60-150 | 10-35 DPI | SBV genome was detectable in at least one organ system of 18 out of 35 foetuses, but limited capacity to induce malformations | [225] | |
+ | FLI inoculuma | Sheep | 21 | Sub-cutaneous | 38-45 | 7 DPI | Preliminary data; indications of transplacental crossing in 64% of foetuses at 7 DPI; no malformations observed | Schmallenberg virus: Final Report EU, 2014c | |
+ | FLI inoculuma | Sheep | 28 | Sub-cutaneous | 45-60 | At birth | Evidence of transplacental SBV infection only found in 14% of lambs at birth; no congenital malformations observed | [119] | |
+ | FLI inoculuma | Sheep | 17 | Sub-cutaneous | 45-60 | At birth | Evidence of transplacental SBV infection; no congenital malformations observed; Placenta of 5 ewes contained infectious SBV at birth | [168] | |
+ | FLI inoculuma | Goats | 10 | Sub-cutaneous | 28-42 | 14-25 DPI | Preliminary data; several haemorrhagic and small foetuses observed after SBV infection | Schmallenberg virus: Final Report EU, 2014c | |
+ | Field | C/S/G | 13 | Vector-mediated | 32-81 | NS | 13 cows with early foetal death after SBV infection | [98] | |