Basic study on inactivation of phage in serum and its mechanism

To investigate factors affecting the viability of phage in the blood and provide a basis for improving in vivo phage display applications, the percentages of active phage in serum and blood at various time points were measured, phage viabilities after various treatment conditions (washed by KSCN, high temperature which can inactive complement, injection of immune suppressor, and use of nude mice) were compared, and some preliminary solutions to overcome this problem were put forward. The results show that serum can cause 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. It was concluded that a heat-labile serum factor, most likely a type of complement-mediated IgM reaction, is responsible for inactivating phage in the blood.