Superinfection exclusion

Superinfection exclusion is a phenomenon in which a preexisting viral infection prevents a secondary infection with the same or a closely related virus. This phenotype is often poorly understood, and may reflect programmed virus superinfection or a kind of antiviral state of the infected cell.

Some bacterial viruses encode proteins to achieve superinfection exclusion. These viral proteins can interfere with DNA release into the host cytoplasm or modify the entry receptor. They can also act as inhibitors of viral peptidoglycan degradation enzymes thereby preventing entry of incoming phages .


Many viruses can make superinfection exclusion, few examples are described below:

Family Genus Virus Superinfection exclusion protein strategy references
Baculoviridae Alphabaculovirus AcMNPV undocumented undocumented
Closteroviridae Closterovirus Citrus tristeza virus p33 undocumented
Flaviridae Hepacivirus Hepatitis C Undocumented post entry
Siphoviridae Lambdalikevirus Enterobacteria phage HK97 gp15 Undocumented
Siphoviridae T5likevirus Enterobacteria phage T5 Lipoprotein Llp Blocks T5 entry receptor FhuA
Myoviridae T4likevirus Enterobacteria phage T4 Immunity protein Imm
Protein spackle Sp
Blocks DNA translocation into host cytoplasm
Inhibits the lysozyme activity
Siphoviridae unclassified Bacteriophage TP-J34 Lipoprotein LTP Blocks DNA ejection into host cytoplasm
Siphoviridae unclassified Lactococcus phage Tuc2009 ORF2 Blocks DNA ejection into host cytoplasm
Podoviridae P22likevirus Enterobacteria phage P22 SieA Blocks DNA translocation into host cytoplasm
Myoviridae Punalikevirus Enterobacteria phage P1 Sim Probably blocks DNA translocation into host cytoplasm