2.2.4 Laboratory tests
Real time polymerase chain reaction (RT PCR) for porcine circovirus 2 (PCV2) and porcine reproductive and respiratory virus (PRRSV, type 1 and type 2) was performed in pools (each containing 4 samples) from collected blood samples and cycle threshold (CT) values from each pool were available. RT PCR detects accumulation of fluorescent signal. CT is defined as the number of cycles required for the fluorescent signal to cross the threshold. Therefore, CT levels are inversely proportional to the amount of nucleic acid in the sample. Zero CT values were interpreted as negative / undetermined results.