Bacteriophage Ecology Group

Bacteriophage Ecology Group Bacteriophage Ecology Group

Abortive Infection (Abi)


A phage infection that ends with both bacterial and phage death.

Many authors define abortive infection more loosely as phage-host combinations that are both bactericidal and in which phage efficiency of plating is low.

Since phage efficiency of plating can be low for reasons other than phage inviability, this operational definition does not exclude bactericidal phage infections that produce phages but at rates that are too low to lead to the formation of plaques. Phage exclusion is sometimes used as a synonym.

Additional categories of infection to consider are productive, reductive, lytic, obligately lytic, professionally lytic, chronic, restrictive, lysogenic, and pseudolysogenic. One can also speak of obligately chronic, obligately productive infection, "destructive" (to the phage), or displaying a reduced infection vigor.

Abortive infections, strictly defined, are destructive but, less strictly defined, instead can be said to display a reduced infection vigor. This is the source of the ambiguity in term usage as indicated above. That is, abortive infection in essence in many cases can be less than fully abortive but still be described as an abortive infection: Substantial reductions in efficiency of plating but without corresponding substantial reduction in efficiency of center of infection.

This is the definition from Adams (1959), p. 439: "Infection accompanied by loss of the infecting phage particle and often death of the bacterium but not yielding a phage progeny under normally sufficient conditions. Infection is abortive because of unusual conditions prevailing before, at the time of, or shortly after infection."

Lwoff (1953), p. 328, provides by contrast a broader definition: "Infection followed neither by lysogenization nor by phage production. The infecting material is not reproduced. A bacterium may or may not survive an abortive infection." This definition is equivalent to what I would describe as either abortive or "restrictive", that is, with the bacterium either not surviving (abortive) or instead surviving (restrictive). Note, though, I am using the term restrictive here in a narrower sense than is often the case, i.e., as equivalent to the situation associated with phage inviability that can follow encounter within hosts with restriction endonucleases.

For addition discussion of the concept of abortive infection as well as additional references, see Hyman and Abedon (2010) and Labrie et al. (2010).


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