🔬 Abortive Infection (Abi)

Discussion

In its strict sense, an abortive infection is a phage–host interaction that is bactericidal — the infected bacterium does not survive — while simultaneously being lethal to the infecting phage lineage, meaning no productive progeny are released. Both partners are destroyed, making abortive infection a dead end for the phage and, from an ecological standpoint, a form of bacterial altruism: an individual bacterium sacrifices itself to protect the surrounding population from phage spread.

Many authors use the term more loosely, however, to encompass any phage–host combination that is both bactericidal and in which efficiency of plating is low — even if some phage progeny are in fact produced. Because a low efficiency of plating can arise from causes other than complete phage inviability (for example, reduced burst size, impaired adsorption, or other manifestations of reduced infection vigor), this operational definition does not exclude bactericidal infections that do produce phages but at rates too low to form plaques. Phage exclusion is sometimes used as a synonym.

The canonical definition comes 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."

A broader definition was offered by Lwoff (1953, p. 328): "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 encompasses what others would distinguish as either abortive (bacterium does not survive) or restrictive (bacterium survives; phage inviable). The latter situation is associated with the action of restriction endonucleases following phage encounter within the host.

In practice, abortive infection shades into reduced infection vigor: infections that are substantially less productive than normal but not fully non-productive. Substantial reductions in efficiency of plating without corresponding reductions in efficiency of center of infection lie in this ambiguous zone — technically productive, but operationally described as abortive by many workers. This is the principal source of terminological ambiguity noted above.

Additional infection categories to consider alongside abortive infection include productive, lytic, chronic, lysogenic, destructive, and reduced infection vigor. Note that abortive infection should not be conflated with lysis from without or with the action of restriction endonucleases per se, as those result in phage death with bacterial survival — i.e., a restrictive rather than abortive outcome.

See also

Productive infection, Lytic infection, Chronic infection, Lysogenic infection, Destructive infection, Reduced infection vigor, Efficiency of plating, Efficiency of center of infection, Restrictive host, Lysogenization, Lysis from without

External links

Note: The Wikipedia article on abortive infection may be limited in scope or accuracy; the PubMed and Google Scholar links provide access to the primary literature.

References

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