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Published Date: 2013-01-23 19:25:46
Subject: PRO/AH/EDR> Schmallenberg virus - Europe (07): (Germany) virus RNA bov semen
Archive Number: 20130123.1511878

SCHMALLENBERG VIRUS - EUROPE (07): (GERMANY) VIRUS RNA IN BOVINE SEMEN
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Date: Wed 23 Jan 2013
From: Martin Beer <Martin.Beer@fli.bund.de> [edited]

Recently, the Friedrich-Loeffler-Institut (FLI) reported about the detection of Schmallenberg virus (SBV)-genome in semen. In 26 semen batches from 11 bulls, SBV-genome could be detected by real-time RT-PCR.

For verification of the infectious status of SBV-positive semen batches, 6 calves were experimentally inoculated in a 1st study. Each animal received pooled semen of 5 straws from one semen batch subcutaneously. The selected semen batches originated from 6 different bulls and represented batches with variable SBV-genome loads. Following inoculation, no clinical symptoms were seen in the animals.

However, for 2 of the 6 calves, an SBV infection could be confirmed by both real-time RT-PCR and subsequent SBV-seroconversion. In 4 of the 6 calves, neither SBV-genomes nor SBV-antibodies could be detected. The 2 semen batches which led to infection of inoculated animals had Cq-values of 26.4 and 34.2, respectively.

Based on those data, it has to be concluded that samples with a medium as well as with a low viral genome load (Cq values over 30) can be potentially infectious for bovines. These results confirm the requirement for a sensitive viral RNA-extraction as well as SBV-genome detection system for testing of semen from SBV-infected bulls.

[Dr Martin Beer and Dr Bernd Hoffmann (Institute of Diagnostic Virology, Friedrich-Loeffler-Institut Insel Riems, Greifswald-Insel Riems, Germany)
Prof Dr Dr Thomas Mettenleiter (President Friedrich-Loeffler-Institut Insel Riems, Greifswald-Insel Riems, Germany)]

--
Dr Martin Beer
Head Institute of Diagnostic Virology
Friedrich-Loeffler-Institut
Am Suedufer 10
17493 Greifswald-Insel Riems
Germany
<Martin.Beer@fli.bund.de>

[The above, firsthand information is gratefully acknowledged. In a previous report from same German authors, they indicated that intermittent SBV excretion was observed in semen of SBV-positive bulls in some of the cases (posting 20121220.1460864). These observations have been confirmed in Dutch and French institutes. They indicate that SBV behaves differently from another Simbu-group teratogenic virus, namely Akabane virus (in Australia).

The current report provides intermediate results of the ongoing research on the issue. The experiment calves were inoculated subcutaneously with the semen. It may be anticipated that the actual potential infectivity of SBV semen will also be tested by insemination.

These essential studies are meant to facilitate the data enabling a science-based decision upon the need for international requirements, including tests, as conditional for trade in semen from SBV-positive/suspected bulls and from SBV-infected zones or countries. - Mod.AS

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