Basic Study Of Inactivation Of Phage In Serum And It's Mechanism

Aim: Phage library is often used to determine short peptides which can bind certain molecules, and as a fast-developing technology, phage display has been widely applied in vivo. We found phage will be inactive in animal when we had injected PHD-C7C library via nose to find short peptides which can pass the blood brain barrier. After that, we quantified this phenomenon and investigated factors affecting the viability of the phage in blood. This will be the basis to improve applications of phage display in vivo.Methods: Measure the percentage of active phage in serum and blood at various time points, compare phage viability after various treatment conditions (wash by KSCN, high temperature which can inactive complement, injection of immune suppressor, and use of nude mice), and put forward some preliminary solutions to overcome this problem.Results: Serum causes rapid inactivation of phage. KSCN and cyclophosphamide can partially, while 60℃treatment can almost completely, inhibit this inactivation effect. The inactivation profile in nude mice is comparable to that in normal mice. Tryptone and BSA can partially overcome the inactivation factor in the serum.Conclusions: A heat-labile serum factor, most likely a type of complement-mediated IgM reaction, is responsible for inactivating phage in the blood.