R. H. Johnson

Observations on the pathogenesis of porcine parvovirus infection

SummaryDifferences in the pathogenesis of porcine parvovirus (PPV) were shown when pregnant gilts were infected by the oral and intramuscular (i.m.) routes.By the oral route, PPV took 23–32 days to cross the placenta following infection of the dam, as compared to 15 days by the i.m. route. Successful transplacental infection occurred following oral infection of dams only in the second third of gestation, whilst i.m. infection resulted in infection of foetuses in both first and second thirds of gestation.Foetal infection resulted in death and mummification only where infection of foetuses occurred before onset of immune competence—estimated at 70 days gestation. Infected foetuses either died before onset of immune competence, or survived to mount an immune response with subsequent death or survival to farrowing.It is suggested in discussion that reproductive failure due to PPV, characterised by mummification or occasional stillbirth, is associated in nature with oral infection, and occurs only when dams are infected in the first part of the midthird of gestation.

Pathogenesis of porcine parvovirus infection: Pathology and immunofluorescence in the foetus

Abstract Porcine foetuses of dams experimentally infected with porcine parvovirus (PPV) showed differing histopathological and immunofluorescent characteristics dependent on gestational age. Histopathological changes without immunofluorescence were evident in foetuses which had passed the stage of immunocompetence, whilst less obvious histopathological changes with significant antigen fluorescence were present in foetuses which had not reached immunocompetence. Such fluorescence was evident in the parenchyma of lung, liver and kidney, and in neurons and vascular endothelium of the cerebrum. Histopathological changes consisted of some vasculitis, perivascular infiltrations and meningitis of the brain, interstitial hepatitis, interstitial nephritis and placentitis with calcification.

A simple procedure to obtain continuous cell lines from bovine peripheral blood leucocytes

A method is described by which cell lines can be readily developed from bovine peripheral leucocytes. Fifteen cell lines have been developed from 25 attempts, passage levels up to 60 being reached. The cell lines are aneuploid and predominantly epithelial, show split ratio capabilities of 1:4 to give monolayers with 5 days of routine passage, and have high resistance to laboratory contamination with bacterial and fungal agents. Data are given concerning establishment, morphology, viral susceptibility and chromosomal counts of established cell lines.