Persistent and contact infection in nursery pigs experimentally infected with porcine reproductive and respiratory syndrome (PRRS) virus
In J. Yoon, DVM, MS; HanSoo Joo, DVM, PhD; William T. Christianson, DVM, PhD; Robert B. Morrison, DVM, PhD; and Gary D. Dial, DVM, PhD
PDF version is available online.
The ability of porcine reproductive and respiratory syndrome (PRRS) virus to induce a persistent infection in nursery pigs was demonstrated, and the establishment of contact infection was compared in groups of sentinel pigs placed into contact with infected pigs at different intervals. Sixteen 3-week-old pigs from a farm free of PRRS were divided into four equal groups. Four pigs were moved into an isolation room and inoculated intranasally with PRRS virus (principal group). Thereafter, three sentinel groups of four pigs each were placed into the room in contact with principal pigs, so that the three sentinel groups were placed in contact on days 3, 10, and 24 post-inoculation (PI), respectively. Clinical signs were observed daily, and blood, nasal swabs, and fecal samples were collected from each pig at 2- to 7-day intervals. Clinical signs were not observed in any of the pigs. Viremia was evident in principal pigs from day 3 up to day 35 PI. In the sentinel groups, the duration of Uremia varied among groups: pigs placed in contact later in the course of the experiment had a shorter viremic period.Viremia was not detected in two of four pigs of sentinel group 3. Duration of virus shedding through nasal secretion and feces was similar to the duration of Uremia for pigs in each group, but virus recovery from nasal and fecal samples was inconsistent compared to virus recovered from the blood. PRRS virus antibody was detected by indirect-fluorescent antibody (IFA) assay in every pig soon after the onset of viremia, and the viremia was maintained at high antibody levels. We discuss the variables in the carrier status and suggest different management practices that may reduce the opportunity for pig-to-pig transmission of PRRS virus on endemically infected farms.
Keywords: PRRS, nursery
Cite as: Yoon IJ, Joo HS, Christianson WT, et al. Persistent and contact infection in nursery pigs experimentally infected with porcine reproductive and respiratory syndrome (PRRS) virus. J Swine Health Prod 1993;1(4):5-8.
Search the AASV web site for pages with similar keywords.