Adeno-Associated virus (AAV) capsid (3D data 2qa0 from http://www.rcsb.org). The single stranded DNA genome inside the capsid is not visible here. The virus is a small, replication-defective, nonenveloped virus. AAV infects humans and some other primates.AAV is not currently known to cause any disease and this lack of pathogenicity has attracted considerable interest from gene therapy researchers together with a other features: AAV can infect non-dividing cells and can stably integrate into human chromosome 19 at a specific site which makes this virus more predictable and a better choice than retroviruses for gene therapy since retroviruses present the threat of random insertion and mutagenesis, which can be followed by cancer. However, removal of the "rep" and "cap" portions of the AAV genome helped create AAV vectors for gene therapy that lack integrative capacity. Selected genes for gene therapy can be inserted in to the AAV vector between the inverted terminal repeats (ITR). AAV DNA is lost through cell division, since the episomal DNA is not replicated along with the host cell DNA. Clinical trials: AAV vectors have been used for treatment of cystic fibrosis and hemophilia B, Parkinson's disease, muscular dystrophy, Arthritis and Alzheimer's disease. The capsid contains 60 proteins. View is along the 2-fold icosahedral symmetry axis. Individual, small spheres are atoms making up the proteins. Hydrogen atoms are not shown.

What is Fifth Disease?

Fifth disease is a mild rash caused by the parvovirus B19. It is most common in children.

What are the symptoms of Fifth Disease?

Patients with mild symptoms may experience “flu-like” symptoms at first. This is when they are contagious. After the rash appears, the patient is normally no longer contagious and can return to school or work. Symptoms include:

  • Fever
  • Runny nose
  • Headache
  • Rash on face and/or body (“slapped cheek” rash)
  • Painful/swollen joints

Who is at risk for Fifth Disease?

Fifth Disease is most common in children, although adults can also become infected. Most of the time, Fifth Disease is mild and goes away after a few days. However, it can cause chronic anemia in people with:

  • Weak immune systems
  • Leukemia patients
  • Cancer patients
  • People with organ transplants
  • People with HIV infections
  • Pregnant women

How is Fifth Disease transmitted?

Fifth disease can spread through respiratory secretions when somebody coughs or sneezes. It can also spread through the blood, which makes it riskier for pregnant women. Normally, patients become immune after getting Fifth Disease once.

How is Fifth Disease diagnosed?

Healthcare providers normally diagnose Fifth Disease based on the “slapped cheek” rash. However, a blood test may be necessary, especially in pregnant women.

How is Fifth Disease treated?

Fifth Disease oftentimes goes away on its own. Over-the-counter treatments can be used for symptoms such as fever and joint pain. If Fifth Disease becomes serious, contact a healthcare provider for the best treatment options.

How can I prevent catching and spreading Fifth Disease?

Patients with Fifth Disease are oftentimes only contagious in the early stages, when they have flu-like symptoms. Once the rash appears, patients are normally no longer contagious.

  • Wash hands thoroughly and often
  • Cover your nose and mouth with a tissue or sleeve when you cough or sneeze
  • Do not touch hands, nose, mouth, or eyes with unwashed hands
  • Avoid contact with sick people
  • Stay home when you are sick

For more information on Fifth Disease, visit http://www.cdc.gov/parvovirusb19/fifth-disease.html.