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BMC Proceedings

Open Access

Evaluation of two interspecific recombinant viruses generated from two neurotropic bovine alphaherpesviruses: genomic characterization and virulence properties in the natural host

  • Maria Paula Del Medico1,
  • Maria Fatima Ladelfa1,
  • Fiorella Kotsias1,
  • Julien Thiry2,
  • François Meurens3,
  • Günther Keil4,
  • Sonia Alejandra Romera1,
  • Etienne Thiry2 and
  • Benoît Muylkens2Email author
BMC Proceedings20082(Suppl 1):P14

Published: 23 September 2008

Bovine herpesvirus 1 (BoHV-1) and bovine herpesvirus 5 (BoHV-5) are two closely related alphaherpesviruses that infect cattle. Both viruses are neurotropic but only BoHV-5 significantly replicates in the central nervous system and induces neurological disease. We previously isolated 2 interspecific recombinant viruses (R1 and R2) between BoHV-1 and BoHV-5 [1]. We report here on the precise characterization of the genetic backgrounds and on the virulence assessment of these two BoHV-1/5 recombinants in their natural host.

An exhaustive PCR/sequencing approach led us to identify the precise location of the two cross-over (CO) points where recombination events occurred between the parental strains. The first CO occurred in a 44 base pairs (bp) sequence of homology at the 3' end of the UL28 encoding genes of BoHV-1 and BoHV-5. The resulting recombinant (R1) inherited 37% of the BoHV-1 genome. The rest of its genome (63%) is homologous to BoHV-5 containing the final region of the unique long (UL) region (from UL27 to UL0.5), the internal and terminal repeats (IR and TR) and the unique short region (US). The second CO occurred in a 39 bp sequence of homology within the UL43 gene. The resulting recombinant (R2) is mainly composed of BoHV-1 sequences (86%). It is homologous to BoHV-1 in a large portion of the UL region (from UL43 to UL0.5), in the IR/TR and in the US region. BoHV-5 sequences account for 14% of its genome content.

In order to study the in vivo virulence of the two recombinants, six groups of 4 animals each were inoculated with the recombinant, parental and control viruses. Data obtained from the virology and serology indicated that parental BoHV-1 and R2 were fully attenuated viruses, BoHV-5 was mildly virulent in the natural host and R1 displayed an intermediate virulence pattern between its two parental strains.

In conclusion, this study provided a detailed analysis of two interspecific recombinant viruses generated from closely related alphaherpesviruses infecting the same natural host. It demonstrated that recombination can occur with very short fragments of sequence homology. Recombination is efficacious at enhancing alphaherpesvirus diversity and is susceptible to increase virus replication properties in vivo.

Authors’ Affiliations

Virology Institute, Veterinary and Agricultural Science Research Centre, National Institute of Agricultural Technology
Virology and Viral Diseases, Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liege
Institut National de la Recherche Agronomique (INRA), UR1282, Infectiologie Animale et Santé Publique
Institute of Molecular Biology, Friedrich-Loeffler-Institutes, Federal Research Centre for Virus Diseases of Animals


  1. Meurens F, Keil GM, Muylkens B, Gogev S, Schynts F, Negro S, Thiry E: Interspecific recombination between two ruminant alphaherpesviruses, bovine herpesviruses 1 and 5. J Virol. 2004, 78: 9828-9836. 10.1128/JVI.78.18.9828-9836.2004.PubMed CentralView ArticlePubMedGoogle Scholar


© Del Medico et al; licensee BioMed Central Ltd. 2008

This article is published under license to BioMed Central Ltd.