Swine influenza (SI) is an acute respiratory disease of pigs, caused by swine influenza virus (SIV). Little is known about the inflammatory response in the lung during acute SI and its correlation with clinical signs or lung pathology. Moreover, until now there has been a limited amount of data available on the relationship between the concentrations of pro- and anti-inflammatory cytokines in the lungs and the serum concentration of acute-phase proteins (APPs) in SIV-infected pigs. In the present study, the porcine inflammatory and immune responses during acute influenza caused by H1N1 SIV (SwH1N1) were studied. Nine pigs were infected intratracheally, and five served as controls. Antibodies against SIV were measured by haemagglutination inhibition assay, and the influenza-virus-specific T-cell response was measured using a proliferation assay. C-reactive protein (CRP), haptoglobin (Hp), serum amyloid A (SAA), and pig major acute-phase protein (Pig-MAP) the concentrations in serum and concentration of IL-1β, IL-6, IL-8, IL-10, TNF-α and IFN-γ in lung tissues were measured using commercial ELISAs.
The influence of age and maternal antibodies on the development and duration of postvaccinal antibody response against Glässer's disease were investigated. Pigs born to immune (MDA-positive) and non-immune (MDA-negative) sows were vaccinated with inactivated vaccine. Vaccination was done according to three different protocols: at 1 and 4, at 2 and 5 or at 4 and 7 weeks of age. There were also two control groups for MDA-negative and MDA-positive pigs. The level of Haemophilus parasuis (Hps) specific antibodies were determined using commercial ELISA test. No serological responses were seen in any of the groups after the first vaccination. Maternally derived antibodies (MDA) against Hps were above the positive level until approximately 3 weeks of life in MDA-positive pigs. In those pigs the strongest postvaccinal humoral response was observed in piglets vaccinated at 4 and 7 weeks of age. In the remaining MDA-positive piglets only slight seroconversion was noted but levels of antibodies never exceeded values considered as positive. All MDA-negative pigs produced Hps-specific antibodies after the second vaccination. The results of the present study indicated that MDA may alter the development and duration of active postvaccinal antibody response. Age of pigs at the moment of vaccination was not associated with the significant differences in the magnitude of antibody response, however influenced the kinetics of decline of Hps-specific antibodies.
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