ESTABLISHMENT AND CHARACTERIZATION OF A PORCINE RUBULAVIRUS (LPMV) PERSISTENT INFECTION IN PORCINE KIDNEY-CELLS

Porcine rubulavirus (LPMV) can establish persistent infections in porc ine kidney cells. Cell cultures characterised at passages 25 and 65 de monstrated haemadsorption, formation of syncytia, and a slower growth rate. The nucleoprotein (NP) and haemagglutinin-neuraminidase (HN) pro tein were present in all cells, although not to the same extent as in wild type infected cells. Incubation of the cell cultures with virus n eutralising antibodies could not cure them from the infection. The cel ls were resistant to LPMV high multiplicity superinfection, but lysed rapidly upon infection with VSV. These cells thus fulfilled the criter ia of a true persistent infection. Viral particles were released into the medium from the persistently infected cells as measured by HA and infection of PK-15 cells with medium from the persistently infected ce lls. The infectious titer of the virus released from the persistently infected cells was 3 logs lower compared to wild type virus, the HN ti ter still being comparable. Virus released from the persistently infec ted cells was unable to cause a lytic infection in PK-15 cells, and sh owed a reduced ability to spread when compared to a LPMV lytic infecti on.