Porcine reproductive and respiratory syndrome virus (PRRSV) causes an extremely detrimental illness manifest by reproductive failure in pregnant sows and respiratory illness in young pigs. Approximately {dollar}250 million is lost annually in nursery age pigs 48 72. Neutralizing antibodies against PRRSV have been shown to have a role in protection against PRRSV infection 74. Recently, it was reported that infection of pigs with strain HLV013 rapidly induced high neutralizing antibody titer 37. In a previous study, it was observed that when a group of pigs was accidentally infected with two unrelated wild mutants of PRRSV that a rise in neutralizing antibodies to heterologous strains occurred (Hocker, Erdman, Harris Unpublished data, 2004). We hypothesized that hyperimmunizing naive gilts with multiple strains of PRRSV, with varying levels of glycosylation, would yield both high homologous and heterologous neutralizing antibody titers. The following reports the results of hyperimmunization of naive gilts with various strains of PRRSV. Also reported are the titers of antibody in pigs passively immunized with plasma derived from this hyperimmunization process. An antibody decay rate was calculated for each pig passively immunized with immune plasma. Passive immunization of piglets against PRRSV and analysis of protection provided post infection were also conducted. Naive sentinel piglets were also monitored and reported to determine the effect on transmission of PRRSV from pigs receiving either normal swine plasma or plasma from pigs hyperimmunized with 3 strains of PRRSV.