Intranasal Exposure to Rift Valley Fever Virus Live-Attenuated Strains Leads to High Mortality Rate in Immunocompetent Mice

Sandra Lacote (1) , Carole Tamietti (2) , Mehdi Chabert (3) , Marie-Pierre Confort (3) , Laurine Conquet (4) , Coralie Pulido (1) , Noémie Aurine (5) , Camille Baquerre (5) , Adrien Thiesson (3) , Bertrand Pain (5) , Marcelo de las Heras (6) , Marie Flamand (2) , Xavier Montagutelli (4) , Philippe Marianneau (1) , Maxime Ratinier (3) , Frédérick Arnaud (3)

1 Laboratoire de Lyon [ANSES]
2 Virologie Structurale - Structural Virology
3 IVPC - Infections Virales et Pathologie Comparée - UMR 754
4 Génétique de la souris - Mouse Genetics
5 SBRI - Institut cellule souche et cerveau / Stem Cell and Brain Research Institute
6 University of Zaragoza - Universidad de Zaragoza [Zaragoza]

Rift Valley fever virus (RVFV) is a pathogenic arthropod-borne virus that can cause serious illness in both ruminants and humans. The virus can be transmitted by an arthropod bite or contact with contaminated fluids or tissues. Two live-attenuated veterinary vaccines—the Smithburn (SB) and Clone 13 (Cl.13)—are currently used during epizootic events in Africa. However, their residual pathogenicity (i.e., SB) or potential of reversion (i.e., Cl.13) causes important adverse effects, strongly limiting their use in the field. In this study, we infected immunocompetent mice with SB or Cl.13 by a subcutaneous or an intranasal inoculation. Interestingly, we found that, unlike the subcutaneous infection, the intranasal inoculation led to a high mortality rate. In addition, we detected high titers and viral N antigen levels in the brain of both the SB- and Cl.13-infected mice. Overall, we unveil a clear correlation between the pathogenicity and the route of administration of both SB and Cl.13, with the intranasal inoculation leading to a stronger neurovirulence and higher mortality rate than the subcutaneous infection.

Mots clés: Rift Valley fever virus; attenuated vaccine strains; intranasal exposure; pathogenicity

Domaines: Virologie

Sandra Lacote, Carole Tamietti, Mehdi Chabert, Marie-Pierre Confort, Laurine Conquet, et al.. Intranasal Exposure to Rift Valley Fever Virus Live-Attenuated Strains Leads to High Mortality Rate in Immunocompetent Mice. Viruses, 2022, Special Issue Rift Valley Fever Epidemiology, Pathogenesis and Host Response, 14 (11), pp.2470. ⟨10.3390/v14112470⟩. ⟨pasteur-03854904⟩