A PRRS vaccination strategy to create PRRS-negative growers/gilts in SPF herds (re)infected with PRRS

PRRS infections still lead to severe economic losses in the pig industry (1). It is possible to create PRRS-negative farms by depopulation and repopulation with negative piglets and gilts from PRRS-free farms. Despite stringent hygienic procedures on these farms, it is difficult to keep them PRRS-free in pig dense countries like the Netherlands. Between Febr-2006 and May-2008, 5 farms in the Netherlands became PRRS-free by depopulation and repopulation with SPF- pigs or by introducing SPF pigs i