Editing Lambda phage (section)

==Multiplicity reactivation and prophage reactivation==
Multiplicity reactivation (MR) is the process by which multiple viral genomes, each containing inactivating genome damage, interact within an infected cell to form a viable viral genome. MR was originally discovered with phage T4, but was subsequently found in phage λ (as well as in numerous other bacterial and mammalian viruses<ref>{{cite journal | vauthors = Michod RE, Bernstein H, Nedelcu AM | title = Adaptive value of sex in microbial pathogens | journal = Infection, Genetics and Evolution | volume = 8 | issue = 3 | pages = 267–285 | date = May 2008 | pmid = 18295550 | doi = 10.1016/j.meegid.2008.01.002 }}</ref>).  MR of phage λ inactivated by UV light depends on the recombination function of either the host or of the infecting phage.<ref>{{cite journal | vauthors = Huskey RJ | title = Multiplicity reactivation as a test for recombination function | journal = Science | volume = 164 | issue = 3877 | pages = 319–320 | date = April 1969 | pmid = 4887562 | doi = 10.1126/science.164.3877.319 | s2cid = 27435591 | bibcode = 1969Sci...164..319H }}</ref>  Absence of both recombination systems leads to a loss of MR.

Survival of UV-irradiated phage λ is increased when the E. coli host is lysogenic for an homologous prophage, a phenomenon termed prophage reactivation.<ref>{{cite journal | vauthors = Blanco M, Devoret R | title = Repair mechanisms involved in prophage reactivation and UV reactivation of UV-irradiated phage lambda | journal = Mutation Research | volume = 17 | issue = 3 | pages = 293–305 | date = March 1973 | pmid = 4688367 | doi = 10.1016/0027-5107(73)90001-8 }}</ref>  Prophage reactivation in phage λ appears to occur by a recombinational repair process similar to that of MR.