Infectious virions of canine parvovirus contain 60 protein subunits that are predominantly VP-2. To view a negatively stained electron micrograph of AAV, click here . To view a computer-generated image of canine parvovirus reconstructed from crystallographic data, click here . These structures are essential for the initiation of genome replication. The pathogenic human parvovirus B19 is difficult to grow in culture, so comparatively little is known about its biology.
All Parvoviruses are highly dependent on cellular functions for genome replication.
Expression of the Parvovirus genome is poorly understood. The helper function required by the defective viruses is thought to be involved in transcription of virus genes. Host cell DNA polymerase is necesary for genome replication. The rep gene is involved in this process, which is poorly understood. There is evidence for vertical transmission of avian AAV in chickens.