PRRSV type 1 can induce aggravation of infection with a mild virulent Actinobacillus serotype 2 strain


Article by:
N. Stockhofe-Zurwieden, H. Wisselink, J. Post, J.M.J. Rebel 2013. International PRRS Symposium

An experimental co-infection study with PRRSV genotype 1, subtype 1 (Lelystad strain) followed by a App serotype 2 infection was performed. Actinobacillus pleuropneumoniae serotype 2 is the most frequently diagnosed serotype in western European swine farms.

3 groups of 10 pigs were used to inoculate:
(group 1:PRRSV/App 2;
group 2: PBS/App2;
group3: PBS/PBS).

Pigs were clinically monitored during 7 days following App infection.

The presence of PRRSV significantly increased the cases of pneumonia compared to App infection alone (Group 1: 6/10 x pneumonia; group 2: 1/10 x pneumonia, group 3: 0/6 x pneumonia).

All PRRSV infected pigs developed fever 4 hours after App infection, whereas pigs infected only with App did not show increased body temperatures. This could be due to reported increase in CD14 expressing cells in the lungs following PRRSV infections, and might explain a higher susceptibility to lung infections by gram-negative bacteria in PRRSV infected pigs.

From this results, it is concluded that PRRSV predisposes for an aggravation of an App infection.