Transplacental infection and embryonic death following maternal exposure to porcine parvovirus near the time of conception

Each of 20 gilts (principals) from a commercial swine herd free of antibody for porcine parvovirus (PPV) was exposed intranasally and orally to PPV at the onset of gestation. The gilts were killed and necropsied 22±1 days later to determine the effect of the virus on their embryos. An equal number of gilts (controls) of the same status, from the same herd, and bred to the same boars, were treated similarly except for exposure to PPV. The following data were obtained at necropsy and from subsequent laboratory tests. Principals had 223 corpora lutea (8 to 16/gilt) and 203 embryos (6 to 16/litter). Porcine parvovirus-infected embryos (1 to 9/litter) were detected in 12 (60 per cent) of the 20 litters. Of the 203 embryos of principals, 169 were alive and 34 were dead and in various stages of decomposition and resorption. Both virus and viral antigen were detected in 7 of the live embryos (1, 1, 2, and 3 in 4 litters) and in 32 of the dead embryos. With 1 exception, infected live embryos were next to infected dead littermates in the uterus suggesting the beginning of intrauterine spread of the virus. Controls had 234 corpora lutea (9 to 15/gilt) and 217 embryos (9 to 14/litter). None of their embryos were infected with PPV and all but 3 were alive.