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Effect of O. porcinus tick salivary gland extract on the African swine fever virus infection in domestic pig

Bernard J., Hutet E., Paboeuf F., Randriamparany T., Holzmuller P., Lancelot R., Rodrigues V., Vial L., Le Potier M.F.. 2016. In : Xth Symposium of the French network for domestic animal immunology. Maisons-Alfort : ANSES, p. 17. Symposium on the French Network for Domestic Animal Immunology (IAD 2016). 10, 2016-03-17/2016-03-18, Ploufragan (France).

African swine fever is a lethal haemorrhagic swine disease with disastrous financial consequences for pig production. Ornithodoros soft ticks are able to transmit the African swine fever virus (ASFV) to pigs in farms, following the natural epidemiologic cycle of the virus. Tick saliva has been shown to modulate the host physiological and immunological responses during feeding on skin, thus affecting viral infection. To better understand the interaction between soft tick, ASFV and pig at the bite location and the possible influence of tick saliva on pig infection by ASFV, salivary gland extract (SGE) of Ornithodoros porcinus, co-inoculated or not with ASFV, was used for intradermal auricular inoculation. Our results showed that, after the virus triggered the disease, pigs inoculated with virus and SGE presented greater hyperthermia than pigs inoculated with virus alone. The density of Langerhans cells was modulated at the tick bite or inoculation site, either through recruitment by ASFV or inhibition by SGE. Additionally, SGE and virus induced macrophage recruitment each. This effect was enhanced when they were co-inoculated. Finally, the co-inoculation of SGE and virus delayed the early local spread of virus to the first lymph node on the inoculation side. This study has shown that the effect of SGE was powerful enough to be quantified in pig both on the systemic and local immune response. We believe this model should be developed with infected tick and could improve knowledge of both tick vector competence and tick saliva immunomodulation.

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