Epsilon Open Archive

Abstract

This thesis summarises and discusses the results of in vitro and in vivo studies on the pathogenesis of porcine rubulavirus infection. Study I describes the development of a blocking ELISA for screening antibodies against PoRV-LPMV. This ELISA is based on a monoclonal antibody (Mab) against the haemagglutinin (HN) protein and has a sensitivity of 99% and specificity of 97%. Study II describes the internalisation of the virus into PK-15 cells using immuno-gold labelled Mabs. The HN protein was detected at the surface and in the cytoplasm of the cells as small and large aggregates after 10 min and 24 h post-infection (pi), respectively. The nucleoprotein (NP) was detected after 24 h pi. Study III describes apoptotic cells in lymphoid tissue and changes in lymphocyte subpopulations in piglets infected with PoRV-LPMV at 5 or 17 days of age. All piglets had increased numbers of apoptotic cells, and the proportions of CD2+, CD8, CD4+ and MHC class II T cells were reduced in piglets infected at 5 days. MHC class II cells remained elevated for 15 days in piglets infected at 17 days. Study IV describes the pathogenesis of central nervous and respiratory system lesions in piglets infected with PoRV-LPMV at 3 and 17 days of age. The younger pigs were more susceptible to infection and developed interstitial pneumonia and encephalomyelitis. Similar but essentially similar lesions were found in the older pigs. Study V describes epididymal lesions in sexually mature boars infected with PoRV-LPMV. These animals developed epididymal necrosis, sperm granulomas and atrophy of the testis. Study VI is an analysis of the effects of the virus in pregnant gilts. Mummies and foetuses with dermal haemorrhages were found and PoRV-LPMV was isolated from foetal brain and lung tissues. The gilts remained clinically normal although virus was isolated from the lung, ovaries and placenta.