Objectives: Bovine Viral Diarrhea Virus (BVDV) is widespread in Italian dairy cattle operations. BVDV infection involves over 70% of dairy herds. At the moment, three genotypes has been demonstrated for BVDV, namely BVDV-1, -2 and -3. Molecular typing demonstrated seventeen subgenotype for BVDV-1, four subgenotypes for both BVDV-2 and BVDV-3. Viral isolation in BVDV outbreaks occurred in Italian dairy herds showed that BVD-1 subgenotype 1b followed by 1e are the most prevalent in Italian dairy cattle operations, while 1a has a low prevalence. BVDV-2 is scarcely demonstrated, not over 4%, of the examined cases. Vaccination and persistently infected (PI) animals detection and culling are the main tools to control- eradicate BVDV in Italy as worldwide. Since vaccine registered in Italy include only BVD 1a and 1b strains, to demonstrate the prevalence of the indicated viral subgenotypes overtime a comparative serological survey has been carried out on serum samples collected in the period 1995-2016. Materials and methods: The study was set up in two steps. The first one included 419 serum samples from 36 dairy herds and collected in 2015-2016; the second one, 200 serum samples from 25 dairy herds collected in the period 1995-2005. All the sera resulted seropositive for BVDV. The samples were kept frozen in a serum bank of the Department Veterinary Science – University of Parma. Most of tested animals belonged to dairy herds located in the Po Valley, Northern Italy and not submitted to vaccination for BVDV. In both the cases, each serum sample was tested for BVD 1a and 1b reference strains by serum neutralization test carried out in parallel. Results: Step 1. Serum neutralization test in parallel showed that 6% of serum samples were negative to both the sugenotypes, 32% were positive for BVDV 1b, 22% for BVDV 1a and for 41% was not possible to demonstrate the subgenotype responsible of the infection. Step 2. The same test showed that 38% of serum samples were positive for BVDV 1a, 30% for BVDV 1b and for 33% was not possible to demonstrate the subgenotype responsible of the infection. Conclusion: In many cases the test did not allowed to demonstrate the subgenotype responsible of the infection. Serum samples recently collected showed a higher positivity to BVDV type 1b. Conversely samples collected in 1995-2005 showed a higher positivity to BVDV 1a. We must underline that this serological survey did not allowed to demonstrate circulation of the other BVDV subgenotypes. Nowadays, on the basis of the obtained serological data, the vaccines containing BVDV 1b strain should be more efficient than 1a vaccines to control BVDV infection in our dairy cattle operations.

Comparative serology to subgenotypes BDV-1a and -1b in Italian dairy cattle operations / Cavirani, Sandro; Taddei, Simone; Cabassi, Clotilde Silvia; Flisi, Sara; Schiano, Emiliana; Fausto, Toni; Giuliano, Pisoni. - STAMPA. - (2018), pp. 233-234. ((Intervento presentato al convegno The 30th World Buiatrics Congress tenutosi a Sapporo nel August 28 to september 1, 2018.

Comparative serology to subgenotypes BDV-1a and -1b in Italian dairy cattle operations

Sandro Cavirani
;
Simone Taddei;Clotilde Silvia Cabassi;FLISI, SARA;Emiliana Schiano;
2018

Abstract

Objectives: Bovine Viral Diarrhea Virus (BVDV) is widespread in Italian dairy cattle operations. BVDV infection involves over 70% of dairy herds. At the moment, three genotypes has been demonstrated for BVDV, namely BVDV-1, -2 and -3. Molecular typing demonstrated seventeen subgenotype for BVDV-1, four subgenotypes for both BVDV-2 and BVDV-3. Viral isolation in BVDV outbreaks occurred in Italian dairy herds showed that BVD-1 subgenotype 1b followed by 1e are the most prevalent in Italian dairy cattle operations, while 1a has a low prevalence. BVDV-2 is scarcely demonstrated, not over 4%, of the examined cases. Vaccination and persistently infected (PI) animals detection and culling are the main tools to control- eradicate BVDV in Italy as worldwide. Since vaccine registered in Italy include only BVD 1a and 1b strains, to demonstrate the prevalence of the indicated viral subgenotypes overtime a comparative serological survey has been carried out on serum samples collected in the period 1995-2016. Materials and methods: The study was set up in two steps. The first one included 419 serum samples from 36 dairy herds and collected in 2015-2016; the second one, 200 serum samples from 25 dairy herds collected in the period 1995-2005. All the sera resulted seropositive for BVDV. The samples were kept frozen in a serum bank of the Department Veterinary Science – University of Parma. Most of tested animals belonged to dairy herds located in the Po Valley, Northern Italy and not submitted to vaccination for BVDV. In both the cases, each serum sample was tested for BVD 1a and 1b reference strains by serum neutralization test carried out in parallel. Results: Step 1. Serum neutralization test in parallel showed that 6% of serum samples were negative to both the sugenotypes, 32% were positive for BVDV 1b, 22% for BVDV 1a and for 41% was not possible to demonstrate the subgenotype responsible of the infection. Step 2. The same test showed that 38% of serum samples were positive for BVDV 1a, 30% for BVDV 1b and for 33% was not possible to demonstrate the subgenotype responsible of the infection. Conclusion: In many cases the test did not allowed to demonstrate the subgenotype responsible of the infection. Serum samples recently collected showed a higher positivity to BVDV type 1b. Conversely samples collected in 1995-2005 showed a higher positivity to BVDV 1a. We must underline that this serological survey did not allowed to demonstrate circulation of the other BVDV subgenotypes. Nowadays, on the basis of the obtained serological data, the vaccines containing BVDV 1b strain should be more efficient than 1a vaccines to control BVDV infection in our dairy cattle operations.
978-460000019-6
Comparative serology to subgenotypes BDV-1a and -1b in Italian dairy cattle operations / Cavirani, Sandro; Taddei, Simone; Cabassi, Clotilde Silvia; Flisi, Sara; Schiano, Emiliana; Fausto, Toni; Giuliano, Pisoni. - STAMPA. - (2018), pp. 233-234. ((Intervento presentato al convegno The 30th World Buiatrics Congress tenutosi a Sapporo nel August 28 to september 1, 2018.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2849983
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