Gestation or Postnatally and Possible Relation to Clinical and Pathological Outcome of Infection 2 Replication in Lymphoid Organs of Pigs Inoculated in Late -- Characteristics of Porcine Circovirus

Abstract. In this study, the characteristics of porcine circovirus–2 (PCV2) replication (infectious virustitrations, distribution, and immunophenotyping of infected cells) in lymphoid organs were examined and relatedto the development of clinical signs and histological lesions in 26 piglets that had been inoculated with PCV2either in utero or at 1 day of age. Piglets inoculated in utero at 92 or 104 gestational days (n 5 12) werecollected by Caesarean section at term and either sacrificed immediately or kept in isolators and allowed tolive postnatally until 35 days postinoculation (PI). Caesarean-derived piglets inoculated at 1 day of age (n 514) were sacrificed at 10, 21, 35, 42, and 49 days PI. Spleen and lymph nodes were collected for virologic andhistopathological examinations. Clinical signs were not observed in any of the piglets. High virus titers(10 4.5–5.7 TCID 50 /g [TCID refers to tissue culture infectious dose]) were detected in 6 of the 26 piglets. Threeof these 6 piglets were euthanized at 10 days PI, and infected cells of the monocyte–macrophage lineage(SWC3