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.