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Detection of bovine lymphotropic herpesvirus DNA in tissues of a bovine aborted fetus in Québec Donald Tremblay, Ossama Allam, Richard Drolet and Carl A. Gagnon
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Project premises In late 2008, the Molecular Biology Diagnostic Laboratory (MBDL) of the Faculty of veterinary medicine of the University of Montreal started a research project to investigate the etiological agents involved in cow abortion in Québec, Canada -Molecular diagnostic (PCR) 4 principal pathogens: -BVDV -Bovine herpesvirus type 1 (IBR) -Leptospira spp -Neospora caninum 1 more (public health concern): Coxiella burnetti
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Data compilation -Analyses are paid for. The results are given to the veterinarian as part of the regular diagnostic (24 hours delay after reception). -The laboratory is sending coolers with identified collecting tubes to the submitting veterinary. -vaccinal status of the herd -live attenuated, -killed viruses and -unvaccinated -Historic -Blood for the serological follow-up
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Methodology and results To date (May 2010) -96 cases submitted -86 placentae -PCRs are done on -placentae (when available) -1 pool of all other tissues.
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Methodology and results Standard qualitative PCR IBR: polymerase A gene detection Leptospira spp.:Gravekamp C. et al., 1993 Real-Time PCR (quantitative) BVD: AgPath-ID BVDV (Life technologies) Neospora caninum: Ghalmi F. et al., 2008 Coxiella burnetti: Klee S.R. et al., 2006
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Results BVDVIBRLeptospira Neospora caninum Coxiella burnetti 5 (5,2)6 (6,3)2 (2,1)9 (9,4)1 (1,0) Number of positive detected by PCR for each pathogen (%)
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Results Since 1 case had BVDV and Leptospira spp. -74 samples (77,1%) without any positive detection -abortion rate in the herd? -IBR: Slight increase since January 2010 (4 cases)
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Results General bacterial detection by 16S rRNA sequencing: -detection on placenta was inconclusive (environmental contamination of the samples) -Very few amplification on individual tissues (contamination) More target: -Mycobacterium spp. -Salmonella spp. -Toxoplasma -General Herpesvirus -General Coronavirus -Campylobacter spp. -Listeria monocytogenes -Chlamydophila spp. -etc….
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General Herpesvirus In January 2010 -case of BHV4 submitted to the MBDL -First tested for IBR detected with a pan-herpesvirus nested-PCR Vandevanter et al., 1996
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General Herpesvirus 250 500 750 1000 1236 Exo I Exo II Exo II’Exo III Motif AMotif BMotif C DFAILKTGVIYGKG1 - DNA polymerase gene - Final fragment of 210 bps - Degenerate primers - Product is unique for each viral species (with little strain variation)
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Results -First 26 cases were tested for detection of pan-herpesvirus -2 amplifications: -IBR (already reported case) -Bovine lymphotropic herpesvirus (BLHV)
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Bovine lymphotropic herpesvirus -Herpesviridae family within the subfamily Gammaherpesvirinae -First described in 1998 (Cornell University) -Rovnak J. et al 1998 -Search of Herpesvirus as co-factor in the bovine leukemia virus (BLV) pathogenesis - 80% positives in animals tested (n=147)
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- Report case in 2006 in the UK - Cobb et al., The Veterinary Report 2006 - Cases of chronic unresponsive endometritis - 33% of a 180-head milking herd was affected with a purulent metritis that did not respond to standard antibiotic therapies - Investigation in 2008 - Banks et al., The Veterinary Journal 2008 -small-scale investigation of UK dairy herds reporting recurrent episodic or chronic non-responsive post-partum metritis -High prevalence in affected herds (but no control unaffected herds) -No association with calving problems Bovine lymphotropic herpesvirus
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Results -Second consecutive abortion, fifth in the last year -Placenta and pool of tissues also positive for Neospora caninum -Individual tissues of the aborted fetus tested -Brain and lymph nodes were positive -Tropism of Herpesvirus for neuronal cells and lymphocytes -No histopathological lesion suggestive of a viral infection could be found in BLHV nested-PCR positives tissues
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Results Investigation in the 60 other submitted placenta - 6 others BLHV amplified - 1/6 had Leptospira spp. infection -Total of 7 cases (11,7% of 60 submitted placenta)
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Conclusion -First description of a Bovine Lymphotropic Herpesvirus in Canada -To our knowledge, it is the first time that BLHV is described in tissues of an aborted fetus -It is difficult to ascertain that BLHV has a role to play in the cause of the abortion (presence of recognized pathogens and no significant viral lesions) -Important to report the presence of BLHV in Canada because it is the first step toward the country improvement of bovine pathogens surveillance.
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