Which of the following statements are correct about gene therapy?SELECT ALL THAT APPLYEngineered adenoviruses and retroviruses are the most common viruses used in gene therapy clinical trials.Retroviruses must be engineered with newer CRISPR-Cas9 systems to induce them to integrate into the host cell genome.The goal of gene therapy is to replace an abnormal human gene with a normal, functional gene.Most gene therapies are targeting infectious agents that cause human disease.Adenoviruses integrate quickly into host cell genomes, so they are highly effective in effecting permanent genetic editing in standard gene therapy.The viruses are genetically engineered to be nonpathogenic, but they must remain infectious in order to deliver their genetic cargo to host cells.

The correct statements about gene therapy are:

1. Engineered adenoviruses and retroviruses are the most common viruses used in gene therapy clinical trials.
2. The goal of gene therapy is to replace an abnormal human gene with a normal, functional gene.
3. The viruses are genetically engineered to be nonpathogenic, but they must remain infectious in order to deliver their genetic cargo to host cells.

The incorrect statements are:

1. Retroviruses must be engineered with newer CRISPR-Cas9 systems to induce them to integrate into the host cell genome. This is not necessarily true, as retroviruses naturally integrate into the host cell genome as part of their life cycle.
2. Most gene therapies are targeting infectious agents that cause human disease. This is incorrect, as most gene therapies are actually targeting genetic disorders.
3. Adenoviruses integrate quickly into host cell genomes, so they are highly effective in effecting permanent genetic editing in standard gene therapy. This is incorrect, as adenoviruses do not integrate into the host genome, they remain episomal.