In vitro and in vivo studies of wild type and recombinant strains of bovine herpesvirus 1 and 5 (Estudios in vivo e in vitro de cepas salvajes y recombinantes de herpesvirus bovino 1 y 5). Mesa redonda Animal Virology: BoHV-1/BoHV-5.

DEL MEDICO ZAJAC, M. PAULA

Gramado

Congreso; XXI Meeting on Virology - V MERCOSUL Meeting on Virology (XXI ENV).; 2010

Bovine herpesvirus 1 (BoHV-1) and bovine herpesvirus 5 (BoHV-5) are two closely related alphaherpesviruses that infect cattle and are able to establish latency. In Argentina, BoHV-1 seroprevalence can reach 60 %, whereas BoHV-5 prevalence is unknown due to the absence of a differential serological test. Since BoHV-1 and BoHV-5 co-circulate, and vaccination against BoHV-1 is not obligatory, the probability of animals being co-infected by them is high, and consequently genetic recombination between these two viruses could occur. Recombination is a highly frequent event among the alphaherpesvirus. Besides, it has a deep impact in BoHV-1 and BoHV-5 pathogenesis and epidemiology since it could lead to virulence restoration of attenuated strains or the increase of the pathogenicity by acquisition of virulence associated genes. In this context, it is of particular interest the development of vaccines that control BoHV-1 and BoHV-5 infections and reduce co-infections risks and natural recombination events between these two viruses. In our laboratory, we developed a bovine experimental infection model with BoHV-5 in order to obtain a tool for the evaluation of the protective efficacy of different vaccines against BoHV-5 infection. Later, we evaluated the immunogenicity and protective efficacy of inactivated vaccines based on BHV-1 or BHV-5 against BHV-5. We demonstrated that the immune response induced by these vaccines is not significantly different and that both of them can protect cattle from nervous signs and viral excretion associated with BoHV-5 infections. In order to obtain information about the impact of natural BoHV-1/5 recombinants in cattle, the in vivo virulence of these recombinants was tested in terms of viral excretion and clinical signs. We observed that cattle infected with the recombinant viruses did not develop clinical signs nor excreted virus. Finally, the genetic background characterization of the BoHV-1/5 recombinants allowed us to identify genomic regions homologous to each parental strain as well as the recombination site between them.