Immunity to porcine rubulavirus infection in adult swine

The immune response against the porcine rubulavirus was analyzed in experimentally infected adult pigs. High titers of virus neutralizing and hemagglutinating inhibitory antibodies were identified in infected animals. The antibody specificity was directed towards HN, M, and NP rubula virion proteins; immunodominance of HN proteins was demonstrated. Peripheral blood mononuclear cells from infected, but not from non-infected pigs proliferated in vitro in response to virus antigenic stimuli, showing a bell-shaped plot with the highest peak at 5 weeks post-infection. Virus-induced lymphoblasts expressed CD4+CD8+ phenotype, whereas lectin-induced lymphoblasts were mainly identified as CD4+CD8− cells. Phenotype analysis of freshly prepared PBMC revealed increased number of both monocytes (PoM1+) and total T lymphocytes (CD2+) early during infection, with reduced values of B lymphocytes at 4 weeks post-infection. Decrease in CD4+CD8− blood cells was observed at 3 weeks post-infection, whereas both CD4−CD8+ and CD4+CD8+ cells increased 1 and 4 weeks post-infection, respectively. This work discusses the relevance of CD4+CD8+ T cells in the control of porcine rubulavirus infection.