Adeno-associated Virus

Adeno-associated viruses (AAV) are non-enveloped, single-stranded DNA viruses heavily studied for their use in gene therapy. The virus belongs to a subset of the Parvoviridae family and in the Dependoparvovirus genus, named because of how reliant they are on other viruses to replicate. AAV must be coinfected alongside helper viruses such as adenovirus, herpes virus simplex type 1 (HSV-1), human cytomegalovirus (CMV), varicella zoster virus (VZV), and human herpesvirus-6 (HHV-6) to replicate. There are 12 AAV serotypes, which can be manipulated for gene delivery. Each serotype has a different tropism, meaning they exhibit a preference for different cell types and tissues in the body (e.g., skeletal muscle, hepatocyte, lymphocytes). AAV is non-pathogenic, meaning it causes no known initial symptoms, and because it does not cause disease in humans, it has shown to be promising in gene therapy research. 

The adeno-associated virus infection does not cause any known acute signs or symptoms. However, individuals can remain infected for their lifetime. Between 30 to 85% of the population has antibodies to AAV. 

Recent research has found a correlation between those infected with AAV2 and childhood hepatitis. Studies have also found that AAV can be linked to reproductive system disorders, specifically an increased rate of miscarriage and liver cancer. Interestingly, those infected with AAV have also been found to have a lower likelihood of developing cervical carcinoma, indicating a protective effect. Although AAV gene therapy is promising, more research is needed to ensure there are no long-term adverse effects.