Adenovirus 5 (Ad5) is a non-enveloped, double-stranded DNA virus belonging to the Adenoviridae family and the Mastadenovirus genus. Adenoviruses are common human pathogens, causing a range of mild to moderate illnesses such as respiratory infections, conjunctivitis, and gastrointestinal infections. Adenovirus 5 is one of the more than 50 known human adenovirus serotypes, which are divided into seven species (A to G).
Although adenovirus infections are typically self-limiting and not severe in healthy individuals, they can be more serious in immunocompromised patients or those with underlying health conditions. Adenoviruses are transmitted via respiratory droplets, direct contact, or fecal-oral route, depending on the serotype.
Adenovirus 5 has been extensively studied in the field of molecular biology and has become an important tool for gene therapy and vaccine development. Its genome is well-characterized, which allows researchers to modify the virus to carry foreign genes or remove its disease-causing potential.
Recombinant adenovirus 5 vectors have been used in various applications, including:
- Gene therapy: Ad5 vectors can deliver functional copies of genes to target cells, which can help treat genetic disorders or other diseases caused by gene mutations.
- Vaccine development: Ad5 vectors can be used to express antigens from various pathogens, triggering an immune response and potentially providing protection against infections. The AstraZeneca COVID-19 vaccine, for example, uses a modified chimpanzee adenovirus vector to deliver the SARS-CoV-2 spike protein to elicit an immune response.
- Cancer therapy: Ad5 vectors can be engineered to target cancer cells and deliver genes that promote cell death or stimulate an immune response against the tumor.
Despite the advantages of Ad5 vectors, there are some limitations to their use, such as pre-existing immunity in the population, which can reduce the effectiveness of the vector. Additionally, the vectors can trigger an immune response that may cause inflammation or other side effects. Researchers continue to work on refining adenovirus vectors to overcome these challenges and develop safer, more effective therapies.