Final answer:
In the formation of a transducing virus, virus-like particles (VLPs) are produced instead of the usual viral proteins Gag, Pol, and Env, leading to non-infectious particles that can integrate into the host genome.
Step-by-step explanation:
In the formation of a transducing virus, the normal proteins generated by the viral RNA—such as Gag (Group-specific antigen), Pol (reverse transcriptase and integrase), and Env (envelope protein)—are not produced. Instead, the processes involved lead to the production of virus-like particles (VLPs) that resemble viruses but do not lead to the production of infectious viral particles.
The Gag protein in transducing viruses mimics the retroviral Env protein by forming most of the coat protein in VLPs. These VLPs encapsulate the retrotransposon RNA in the cytoplasm, then form double-stranded reverse transcripts (cDNAs) within the VLPs which can re-enter the nucleus to integrate into genomic target DNA. This is in contrast to infectious retroviruses which lyse the host cell to release new infectious particles.