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Abstract :
[en] Alcelaphine herpesvirus 1 (AlHV-1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (WD-MCF) when cross-species transmitted to a variety of susceptible species of the Artiodactyla order. Experimentally, WD-MCF can be reproduced in rabbits. The lesions observed are very similar to those described in natural host species. Recently, we demonstrated that WD-MCF induced by AlHV-1 in rabbits is associated with the proliferation of CD8+ cells supporting a latent type of infection. In the present study, we investigated whether the virus could be detected ex vivo in the tissues of rabbits developing WD-MCF. Taking advantage of the recent cloning of the AlHV-1 genome as a bacterial artificial chromosome (BAC), we produced a recombinant plasmid encoding a firefly luciferase (LUC) expression cassette inserted in a non-coding region of the AlHV-1 genome. In vitro, the reconstituted AlHV-1 LUC strain replicated comparably to the parental strain in permissive cells and was able to induce a bioluminescent signal. In vivo, rabbits infected with the AlHV-1 LUC strain developed WD-MCF similarly to the parental wild-type strain with hyperthermia, increased CD8/CD4 ratio and viral genomic charge over time in PBMC and in lymph nodes at time of death. To identify the presence of AlHV-1 infection ex vivo, various organs of infected rabbits developing WD-MCF were analysed by bioluminescent imaging. Luciferase activity could be detected macroscopically at the time of death in most of analyzed organs including lung, popliteal and mesenteric lymph nodes, spleen, liver, kidney and appendix. Infectious virus could be isolated following co-cultures of lymph node and permissive cells, and the isolated virus retained the ability to induce a bioluminescent signal. In conclusion, we produced an AlHV-1 LUC recombinant and we were able to detect the AlHV-1 infection ex vivo in many organs at the time of death.
