Figure 4From: Generation of an infectious clone of HuN4-F112, an attenuated live vaccine strain of porcine reproductive and respiratory syndrome virusDifferentiation between cloned virus and parental HuN4-F112 strain. A Mlu I restriction site was introduced in the full-length cDNA clone of HuN4-F112 to allow discrimination between cloned virus (tagged with the Mlu I site) and parental virus (lacks the Mlu I site). The presence of a Mlu I restriction site resulted in fragments of 460 bp and 92 bp. 1 and 4 were RT-PCR fragments undigested, 2 and 3 were RT-PCR fragments digested by Mlu I.Back to article page