Abstract Book of EAVLD2012 - eavld congress 2012

S3 - O - 08
SCHMALLENBERGVIRUS: SEROLOGICAL STUDIES IN GERMAN HOLDINGS
Horst Schirrmeier, Bernd Hoffmann, Martin Beer
Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald-Insel Riems, Germany
Introduction
In August 2011 first indications of a previously unknown disease
in dairy cattle were observed in North Rhine-Westphalia,
Germany, and in the Netherlands. Fever, decreased milk
production and in some cases also diarrhea were the major
symptoms. In November 2011, the detection of a novel
Orthobunyavirus in blood samples of acutely diseased dairy cows
was reported by the Friedrich-Loeffler-Institut, and the the virus
was named as Schmallenberg virus (SBV). Since December
2011, congenital malformations were observed, initially in sheep
and goats, and subsequently also in calves. A real-time RT-PCR
was developed very early after the first detection, and first
serological methods were established for serological studies. The
first findings including investigations about the SBV-prevalence in
Germany are reported.
Materials & methods
The following methods for the detection of SBV-specific
antibodies were established and used:
1. serumneutralization test (SNT) in BHK-21 cells, clone
CT (L164, CCLV, Insel Riems) using the cell culture
isolate “Schmallenberg BH80”.
2. indirect immunofluorescence in a multi-plate format
with SBV-infected BHK-21 cells, using the SBVinfected
cell clone BRS5 (L194, CCLV Insel Riems) as
antigen matrix (Vero cells were used as an alternative
cell culture).
3. Indirect ELISA (in house development as well as a
prototype batch of a commercial ELISA assay).
Within a nationwide first monitoring study, cattle, sheep and goat
sera were tested for SBV antibodies. Furthermore, sera from
malformed calves and pre-colostral sera of newborn ruminants
were investigated to improve diagnostic options in clinically and
pathologically suspected, but PCR negative cases. A few sera
from wild ungulates were also included, and in vitro crossreaction
studies with other members of the Orthobunyavirus
family were performed.
Results & discussion
SBV-specific antibodies could be detected in serum samples
from cattle and sheep from all included federal states. The
observed incidence was within a range of 10% to 60 %, with a
single outlier of more than 90 %. Positive results were obtained
most frequently in the epidemiological “core regions” in the
Northwestern parts of Germany. The number of sero-reactors
corresponded very well with the frequency of the notified clinical
cases. However, the in-herd prevalence differed substantially and
varied between single reactors and up to 80 % positive animals,
and was generally higher in cattle herds than in sheep flocks.
Apart from domestic ruminants, antibodies could be also detected
in samples from bisons, roe deer, red deer and from one camel
and lama, respectively. Furthermore, SBV-specific antibodies
could be also detected in samples from PCR-negative animals as
well as in sera of malformed calves without colostrum uptake.
Our results will allow better insights into the epidemiolocial
background of the SBV-infection, will expand the knowledge
about pathogenetic mechanisms, and are able to substantiate the
SBV case definition in PCR-negative animals.
References
Hoffmann B, Scheuch M, Höper D, Jungblut R, Holsteg M, Schirrmeier H,
Eschbaumer M, Goller KV, Wernike K, Fischer M, Breithaupt A,
Mettenleiter TC, Beer M. (2012). Novel orthobunyavirus in cattle, Europe,
2011, Emerg Infect Dis. 2012 Mar;18(3):469-72
Orthobunyavirus, serology,