The use of DNA hybridization to study infection of swine semen, preimplantation embryos and fetuses with porcine parvovirus.

摘要

The thesis is based on 3 studies involving swine semen, preimplantation embryos and fetuses infected with porcine parvovirus (PPV).; In the initial study, the association of PPV with semen components in vitro along with the shedding pattern of PPV from semen of oronasally infected boars was investigated. PPV DNA was detected in association with spermatozoa that had been incubated in vitro with PPV and washed multiple times. In the in vivo experiment, prior to the inoculation of boars with PPV, a catheter was surgically implanted in the vas deferens for the purpose of collecting epididymal semen free of extrinsic contamination. PPV DNA was detected in the epididymal semen of 3 (n = 4) boars at days 5 through 9 postinoculation (p.i.).; The second study focused on the interaction of PPV with preimplantation porcine embryos. Cultured embryos were exposed to virulent NADL-8 isolate of PPV or the avirulent KBSH isolate by microinjection or incubation with virus. Both treatments failed to significantly inhibit in vitro development. Replicative form PPV DNA was found in viable embryos after microinjection with KBSH and NADL-8 strains of PPV and after incubation with KBSH strain.; The third study evaluated the possibility of PPV to establish persistent infection in swine exposed in utero and followed through maturity. Eighty to 95 day gestational age fetuses were inoculated with PPV. PPV DNA was detected in tissues from the lungs of a pig euthanized 9 weeks p.i. and from the retropharyngeal lymph node of a pig euthanized 31 weeks p.i. Shedding of virus was not observed.; These studies demonstrated that PPV is shed transiently in semen of boars following oronasal inoculation with implications to breeding herds and artificial insemination centers. Other results indicate that some porcine embryos develop normally in vitro after infection of the blastomeres with PPV. PPV infection may be inapparent microscopically for periods sufficient to allow transfer of the embryos and associated infectious agents to recipients. This research demonstrated that pigs exposed in utero to PPV may be persistently infected, however the likelihood of shedding to contact animals is minimal.