The immune response after vaccination is similar to that after a natural PRRS infection.
PRRSV-specific antibodies can persist for more than one year post-infection. Maternally derived antibodies (MDA) against PRRSV usually disappear by 6 weeks of age. Most reports indicate that MDA have a protective effect.
The humoral response can usually be detected from two weeks after vaccination. Typically, the first neutralizing antibodies appear from 4 weeks onwards.The timing of the humoral response may be influenced by the strain of virus used and differences in the immune response of individual animals. Maximum antibody titres are usually obtained at approximately 4 weeks after vaccination. A cellular response, as seen after infection with PRRS field virus, can also be shown after vaccination. Vaccination with Porcilis PRRS, both intramuscular (Group 1) and intradermal (Group 2), stimulates the peripheral lymphocyte subpopulation, compared with non vaccinated pigs (Group 3) (Borghetti et al. 2003).
Peripheral lymphocytes subpopulations (CD4+Th)
Peripheral lymphocytes subpopulations (CD8+ cells)