Reproduction of lesions of postweaning multisystemic wasting syndrome in gnotobiotic piglets

Neonatal gnotobiotic piglets were inoculated with tissue homogenates and lo w- and high-passage cell culture material to determine if the lesions of th e newly described porcine postweaning multisystemic wasting syndrome (PMWS) could be reproduced. For this, 17 3-day-old gnotobiotic piglets were inocu lated intranasally with pelleted chloroform-treated, filtered extracts from cell cultures, filter-sterilized homogenates of lymphoid tissue from PMWS- affected piglets, or control materials. Piglets were maintained in germ-fre e isolators for up to 5 weeks after infection prior to euthanasia and colle ction of samples for analysis. All piglets inoculated with the viral inocul a developed lesions typical of PMWS, including generalized lymphadenopathy, hepatitis, nephritis, interstitial pneumonia, myocarditis, and gastritis. Porcine circovirus (PCV), as well as porcine parvovirus (PPV), was detected in tissues by virus reisolation, polymerase chain reaction analysis, or im munohistochemistry. All infected piglets developed moderate to high titers of antibody to PCV and moderate titers to PPV. No lesions, virus, or virus- specific antibodies were detected in sham-inoculated or uninoculated contro l piglets. These studies demonstrate that the lesions of PMWS can be experi mentally reproduced in gnotobiotic piglets using filterable viral agents de rived from pigs with PMWS and provide an experimental basis for further inv estigation into the pathogenesis and control of this emerging infectious di sease in swine.