title: Suppression of NK cell-mediated cytotoxicity against PRRSV-infected porcine alveolar macrophages in vitro.
abstract: The adaptive immunity against PRRSV has already been studied in depth, but only limited data are available on the innate immune responses against this pathogen. In the present study, we analyzed the interaction between porcine natural killer (NK) cells and PRRSV-infected primary porcine alveolar macrophages (PAMs), since NK cells are one of the most important components of innate immunity and PAMs are primary target cells of PRRSV infection. NK cytotoxicity assays were performed using enriched NK cells as effector cells and virus-infected or mock-inoculated PAMs as target cells. The NK cytotoxicity against PRRSV-infected PAMs was decreased starting from 6h post inoculation (hpi) till the end of the experiment (12 hpi) and was significantly lower than that against pseudorabies virus (PrV)-infected PAMs. UV-inactivated PRRSV also suppressed NK activity, but much less than infectious PRRSV. Furthermore, co-incubation with PRRSV-infected PAMs inhibited degranulation of NK cells. Finally, using the supernatant of PRRSV-infected PAMs collected at 12 hpi showed that the suppressive effect of PRRSV on NK cytotoxicity was not mediated by soluble factors. In conclusion, PRRSV-infected PAMs showed a reduced susceptibility toward NK cytotoxicity, which may represent one of the multiple evasion strategies of PRRSV.
authors.affiliation: Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
authors.forename: Jun
authors.initials: J
authors.lastname: Cao
authors.forename: Korneel
authors.initials: K
authors.lastname: Grauwet
authors.forename: Ben
authors.initials: B
authors.lastname: Vermeulen
authors.forename: Bert
authors.initials: B
authors.lastname: Devriendt
authors.forename: Ping
authors.initials: P
authors.lastname: Jiang
authors.forename: Herman
authors.initials: H
authors.lastname: Favoreel
authors.forename: Hans
authors.initials: H
authors.lastname: Nauwynck
mesh_terms: D000818:Animals; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D013552:Swine