#02-132

Complete

Date Full Report Received

01/23/2004

Date Abstract Report Received

07/26/2006

Investigation

Institution:
Primary Investigator:

Porcine circovirus type 2 (PCV-2) infection is now recognized to be a common subclinical infection of swine of all ages. Disease expression as postweaning multisystemic wasting syndrome (PMWS) is seen in piglets in the post-weaning stage of development and is a reflection of systemic upregulation of the virus infection in the neonatal and immediate post-weaning period. Gravid sows are seropositive for PCV-2 and they transmit maternal “protective” antibodies to their off-spring by colostrum. While this antibody is assumed to be protective, careful study of the disease process in the field indicate that piglets acquire the infection very early in life, within several days to several weeks after farrowing. The experiments described herein have demonstrated that the nonencapsidated closed circular form of PCV-2 viral DNA is infectious when inoculated into PCV-2-susceptible gnotobiotic swine. The potential importance of this observation relates to the strong possibility that suckling piglets may acquire the infection from the environment even though they have high levels of maternal origin virus neutralizing antibodies. While much work remains to be done, these experiments highlight the distinct possibility that infection of piglets by this unconventional means permits the establishment of viral infection within them even though they are seropositive through colostral (maternal) immune mechanisms.