Defective interfering particle

Defective interfering particles (DIPs) are sub-viral entities that are sometimes found during a virus infection. During genome replication of a competent virus, sometimes defective genomes are generated that can still be packaged and form virus particles. However, the genome inside of such particles are not competent to replicate since they are missing part or most of their genetic information. Therefore, DIPs cannot sustain an infection by themselves. Instead, they depend on co-infection with a suitable helper virus, which can provide the gene functions that are absent from the DIPs.

The DIP interferes with the helper virus by competing for enzymes that the helper virus requires to multiply. Due to their smaller size, the genomes of the DIPs are more efficiently replicated than the full length viral genome, generating a very large number of non-infectious particles. DIPs have been shown to play a role in pathogenesis of certain viruses (such as Paramyxoviruses) in the fact that they attenuate some aspect of infection that would otherwise cause the host to be killed too rapidly. It is thought that the ability to generate defective genome during a replication has been selected by the evolution, since it increases the infection period and thereby, conferring the virus with more time to spread to new host cells.

    References

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